text: /*-------------------------------------------------------------------------
   *
   * relcache.c
   *	  POSTGRES relation descriptor cache code
   *
   * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/utils/cache/relcache.c
   *
   *-------------------------------------------------------------------------
   */
  /*
   * INTERFACE ROUTINES
   *		RelationCacheInitialize			- initialize relcache (to empty)
   *		RelationCacheInitializePhase2	- initialize shared-catalog entries
   *		RelationCacheInitializePhase3	- finish initializing relcache
   *		RelationIdGetRelation			- get a reldesc by relation id
   *		RelationClose					- close an open relation
   *
   * NOTES
   *		The following code contains many undocumented hacks.  Please be
   *		careful....
   */
  #include "postgres.h"
  
  #include <sys/file.h>
  #include <fcntl.h>
  #include <unistd.h>
  
  #include "access/htup_details.h"
  #include "access/multixact.h"
  #include "access/nbtree.h"
  #include "access/parallel.h"
  #include "access/reloptions.h"
  #include "access/sysattr.h"
  #include "access/table.h"
  #include "access/tableam.h"
  #include "access/tupdesc_details.h"
  #include "access/xact.h"
  #include "access/xlog.h"
  #include "catalog/catalog.h"
  #include "catalog/indexing.h"
  #include "catalog/namespace.h"
  #include "catalog/partition.h"
  #include "catalog/pg_am.h"
  #include "catalog/pg_amproc.h"
  #include "catalog/pg_attrdef.h"
  #include "catalog/pg_auth_members.h"
  #include "catalog/pg_authid.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_database.h"
  #include "catalog/pg_namespace.h"
  #include "catalog/pg_opclass.h"
  #include "catalog/pg_proc.h"
  #include "catalog/pg_publication.h"
  #include "catalog/pg_rewrite.h"
  #include "catalog/pg_shseclabel.h"
  #include "catalog/pg_statistic_ext.h"
  #include "catalog/pg_statistic_ext_data.h"
  #include "catalog/pg_subscription.h"
  #include "catalog/pg_tablespace.h"
  #include "catalog/pg_trigger.h"
  #include "catalog/pg_type.h"
  #include "catalog/schemapg.h"
  #include "catalog/storage.h"
  #include "commands/policy.h"
  #include "commands/trigger.h"
  #include "miscadmin.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/optimizer.h"
  #include "rewrite/rewriteDefine.h"
  #include "rewrite/rowsecurity.h"
  #include "storage/lmgr.h"
  #include "storage/smgr.h"
  #include "utils/array.h"
  #include "utils/builtins.h"
  #include "utils/datum.h"
  #include "utils/fmgroids.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/relmapper.h"
  #include "utils/resowner_private.h"
  #include "utils/snapmgr.h"
  #include "utils/syscache.h"
  #ifdef ADB
  #include "catalog/pgxc_node.h"
  #include "commands/defrem.h"
  #include "pgxc/pgxc.h"
  #include "postmaster/autovacuum.h"
  #endif /* ADB */
  
  #define RELCACHE_INIT_FILEMAGIC		0x573266	/* version ID value */
  #ifdef ADB
  extern bool enable_readsql_on_slave;
  extern bool singleuser;
  #endif
  
  /*
   * Whether to bother checking if relation cache memory needs to be freed
   * eagerly.  See also RelationBuildDesc() and pg_config_manual.h.
   */
  #if defined(RECOVER_RELATION_BUILD_MEMORY) && (RECOVER_RELATION_BUILD_MEMORY != 0)
  #define MAYBE_RECOVER_RELATION_BUILD_MEMORY 1
  #else
  #define RECOVER_RELATION_BUILD_MEMORY 0
  #ifdef CLOBBER_CACHE_ENABLED
  #define MAYBE_RECOVER_RELATION_BUILD_MEMORY 1
  #endif
  #endif
  
  /*
   *		hardcoded tuple descriptors, contents generated by genbki.pl
   */
  static const FormData_pg_attribute Desc_pg_class[Natts_pg_class] = {Schema_pg_class};
  static const FormData_pg_attribute Desc_pg_attribute[Natts_pg_attribute] = {Schema_pg_attribute};
  static const FormData_pg_attribute Desc_pg_proc[Natts_pg_proc] = {Schema_pg_proc};
  static const FormData_pg_attribute Desc_pg_type[Natts_pg_type] = {Schema_pg_type};
  static const FormData_pg_attribute Desc_pg_database[Natts_pg_database] = {Schema_pg_database};
  static const FormData_pg_attribute Desc_pg_authid[Natts_pg_authid] = {Schema_pg_authid};
  static const FormData_pg_attribute Desc_pg_auth_members[Natts_pg_auth_members] = {Schema_pg_auth_members};
  static const FormData_pg_attribute Desc_pg_index[Natts_pg_index] = {Schema_pg_index};
  static const FormData_pg_attribute Desc_pg_shseclabel[Natts_pg_shseclabel] = {Schema_pg_shseclabel};
  static const FormData_pg_attribute Desc_pg_subscription[Natts_pg_subscription] = {Schema_pg_subscription};
  #ifdef ADB
  static const FormData_pg_attribute Desc_pgxc_node[Natts_pgxc_node] = {Schema_pgxc_node};
  #endif /* ADB */
  
  /*
   *		Hash tables that index the relation cache
   *
   *		We used to index the cache by both name and OID, but now there
   *		is only an index by OID.
   */
  typedef struct relidcacheent
  {
  	Oid			reloid;
  	Relation	reldesc;
  } RelIdCacheEnt;
  
  static HTAB *RelationIdCache;
  
  /*
   * This flag is false until we have prepared the critical relcache entries
   * that are needed to do indexscans on the tables read by relcache building.
   */
  bool		criticalRelcachesBuilt = false;
  
  /*
   * This flag is false until we have prepared the critical relcache entries
   * for shared catalogs (which are the tables needed for login).
   */
  bool		criticalSharedRelcachesBuilt = false;
  
  /*
   * This counter counts relcache inval events received since backend startup
   * (but only for rels that are actually in cache).  Presently, we use it only
   * to detect whether data about to be written by write_relcache_init_file()
   * might already be obsolete.
   */
  static long relcacheInvalsReceived = 0L;
  
  /*
   * eoxact_list[] stores the OIDs of relations that (might) need AtEOXact
   * cleanup work.  This list intentionally has limited size; if it overflows,
   * we fall back to scanning the whole hashtable.  There is no value in a very
   * large list because (1) at some point, a hash_seq_search scan is faster than
   * retail lookups, and (2) the value of this is to reduce EOXact work for
   * short transactions, which can't have dirtied all that many tables anyway.
   * EOXactListAdd() does not bother to prevent duplicate list entries, so the
   * cleanup processing must be idempotent.
   */
  #define MAX_EOXACT_LIST 32
  static Oid	eoxact_list[MAX_EOXACT_LIST];
  static int	eoxact_list_len = 0;
  static bool eoxact_list_overflowed = false;
  
  #define EOXactListAdd(rel) \
  	do { \
  		if (eoxact_list_len < MAX_EOXACT_LIST) \
  			eoxact_list[eoxact_list_len++] = (rel)->rd_id; \
  		else \
  			eoxact_list_overflowed = true; \
  	} while (0)
  
  /*
   * EOXactTupleDescArray stores TupleDescs that (might) need AtEOXact
   * cleanup work.  The array expands as needed; there is no hashtable because
   * we don't need to access individual items except at EOXact.
   */
  static TupleDesc *EOXactTupleDescArray;
  static int	NextEOXactTupleDescNum = 0;
  static int	EOXactTupleDescArrayLen = 0;
  
  /*
   *		macros to manipulate the lookup hashtable
   */
  #define RelationCacheInsert(RELATION, replace_allowed)	\
  do { \
  	RelIdCacheEnt *hentry; bool found; \
  	hentry = (RelIdCacheEnt *) hash_search(RelationIdCache, \
  										   (void *) &((RELATION)->rd_id), \
  										   HASH_ENTER, &found); \
  	if (found) \
  	{ \
  		/* see comments in RelationBuildDesc and RelationBuildLocalRelation */ \
  		Relation _old_rel = hentry->reldesc; \
  		Assert(replace_allowed); \
  		hentry->reldesc = (RELATION); \
  		if (RelationHasReferenceCountZero(_old_rel)) \
  			RelationDestroyRelation(_old_rel, false); \
  		else if (!IsBootstrapProcessingMode()) \
  			elog(WARNING, "leaking still-referenced relcache entry for \"%s\"", \
  				 RelationGetRelationName(_old_rel)); \
  	} \
  	else \
  		hentry->reldesc = (RELATION); \
  } while(0)
  
  #define RelationIdCacheLookup(ID, RELATION) \
  do { \
  	RelIdCacheEnt *hentry; \
  	hentry = (RelIdCacheEnt *) hash_search(RelationIdCache, \
  										   (void *) &(ID), \
  										   HASH_FIND, NULL); \
  	if (hentry) \
  		RELATION = hentry->reldesc; \
  	else \
  		RELATION = NULL; \
  } while(0)
  
  #define RelationCacheDelete(RELATION) \
  do { \
  	RelIdCacheEnt *hentry; \
  	hentry = (RelIdCacheEnt *) hash_search(RelationIdCache, \
  										   (void *) &((RELATION)->rd_id), \
  										   HASH_REMOVE, NULL); \
  	if (hentry == NULL) \
  		elog(WARNING, "failed to delete relcache entry for OID %u", \
  			 (RELATION)->rd_id); \
  } while(0)
  
  
  /*
   * Special cache for opclass-related information
   *
   * Note: only default support procs get cached, ie, those with
   * lefttype = righttype = opcintype.
   */
  typedef struct opclasscacheent
  {
  	Oid			opclassoid;		/* lookup key: OID of opclass */
  	bool		valid;			/* set true after successful fill-in */
  	StrategyNumber numSupport;	/* max # of support procs (from pg_am) */
  	Oid			opcfamily;		/* OID of opclass's family */
  	Oid			opcintype;		/* OID of opclass's declared input type */
  	RegProcedure *supportProcs; /* OIDs of support procedures */
  } OpClassCacheEnt;
  
  static HTAB *OpClassCache = NULL;
  
  
  /* non-export function prototypes */
  
  static void RelationDestroyRelation(Relation relation, bool remember_tupdesc);
  static void RelationClearRelation(Relation relation, bool rebuild);
  
  static void RelationReloadIndexInfo(Relation relation);
  static void RelationReloadNailed(Relation relation);
  static void RelationFlushRelation(Relation relation);
  static void RememberToFreeTupleDescAtEOX(TupleDesc td);
  #ifdef USE_ASSERT_CHECKING
  static void AssertPendingSyncConsistency(Relation relation);
  #endif
  static void AtEOXact_cleanup(Relation relation, bool isCommit);
  static void AtEOSubXact_cleanup(Relation relation, bool isCommit,
  								SubTransactionId mySubid, SubTransactionId parentSubid);
  static bool load_relcache_init_file(bool shared);
  static void write_relcache_init_file(bool shared);
  static void write_item(const void *data, Size len, FILE *fp);
  
  static void formrdesc(const char *relationName, Oid relationReltype,
  					  bool isshared, int natts, const FormData_pg_attribute *attrs);
  
  static HeapTuple ScanPgRelation(Oid targetRelId, bool indexOK, bool force_non_historic);
  static Relation AllocateRelationDesc(Form_pg_class relp);
  static void RelationParseRelOptions(Relation relation, HeapTuple tuple);
  static void RelationBuildTupleDesc(Relation relation);
  static Relation RelationBuildDesc(Oid targetRelId, bool insertIt);
  static void RelationInitPhysicalAddr(Relation relation);
  static void load_critical_index(Oid indexoid, Oid heapoid);
  static TupleDesc GetPgClassDescriptor(void);
  static TupleDesc GetPgIndexDescriptor(void);
  static void AttrDefaultFetch(Relation relation, int ndef);
  static int	AttrDefaultCmp(const void *a, const void *b);
  static void CheckConstraintFetch(Relation relation);
  static int	CheckConstraintCmp(const void *a, const void *b);
  static void InitIndexAmRoutine(Relation relation);
  static void IndexSupportInitialize(oidvector *indclass,
  								   RegProcedure *indexSupport,
  								   Oid *opFamily,
  								   Oid *opcInType,
  								   StrategyNumber maxSupportNumber,
  								   AttrNumber maxAttributeNumber);
  static OpClassCacheEnt *LookupOpclassInfo(Oid operatorClassOid,
  										  StrategyNumber numSupport);
  static void RelationCacheInitFileRemoveInDir(const char *tblspcpath);
  static void unlink_initfile(const char *initfilename, int elevel);
  
  
  /*
   *		ScanPgRelation
   *
   *		This is used by RelationBuildDesc to find a pg_class
   *		tuple matching targetRelId.  The caller must hold at least
   *		AccessShareLock on the target relid to prevent concurrent-update
   *		scenarios; it isn't guaranteed that all scans used to build the
   *		relcache entry will use the same snapshot.  If, for example,
   *		an attribute were to be added after scanning pg_class and before
   *		scanning pg_attribute, relnatts wouldn't match.
   *
   *		NB: the returned tuple has been copied into palloc'd storage
   *		and must eventually be freed with heap_freetuple.
   */
  static HeapTuple
  ScanPgRelation(Oid targetRelId, bool indexOK, bool force_non_historic)
  {
  	HeapTuple	pg_class_tuple;
  	Relation	pg_class_desc;
  	SysScanDesc pg_class_scan;
  	ScanKeyData key[1];
  	Snapshot	snapshot = NULL;
  
  	/*
  	 * If something goes wrong during backend startup, we might find ourselves
  	 * trying to read pg_class before we've selected a database.  That ain't
  	 * gonna work, so bail out with a useful error message.  If this happens,
  	 * it probably means a relcache entry that needs to be nailed isn't.
  	 */
  	if (!OidIsValid(MyDatabaseId))
  		elog(FATAL, "cannot read pg_class without having selected a database");
  
  	/*
  	 * form a scan key
  	 */
  	ScanKeyInit(&key[0],
  				Anum_pg_class_oid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(targetRelId));
  
  	/*
  	 * Open pg_class and fetch a tuple.  Force heap scan if we haven't yet
  	 * built the critical relcache entries (this includes initdb and startup
  	 * without a pg_internal.init file).  The caller can also force a heap
  	 * scan by setting indexOK == false.
  	 */
  	pg_class_desc = table_open(RelationRelationId, AccessShareLock);
  
  	/*
  	 * The caller might need a tuple that's newer than the one the historic
  	 * snapshot; currently the only case requiring to do so is looking up the
  	 * relfilenode of non mapped system relations during decoding. That
  	 * snapshot can't change in the midst of a relcache build, so there's no
  	 * need to register the snapshot.
  	 */
  	if (force_non_historic)
  		snapshot = GetNonHistoricCatalogSnapshot(RelationRelationId);
  
  	pg_class_scan = systable_beginscan(pg_class_desc, ClassOidIndexId,
  									   indexOK && criticalRelcachesBuilt,
  									   snapshot,
  									   1, key);
  
  	pg_class_tuple = systable_getnext(pg_class_scan);
  
  	/*
  	 * Must copy tuple before releasing buffer.
  	 */
  	if (HeapTupleIsValid(pg_class_tuple))
  		pg_class_tuple = heap_copytuple(pg_class_tuple);
  
  	/* all done */
  	systable_endscan(pg_class_scan);
  	table_close(pg_class_desc, AccessShareLock);
  
  	return pg_class_tuple;
  }
  
  /*
   *		AllocateRelationDesc
   *
   *		This is used to allocate memory for a new relation descriptor
   *		and initialize the rd_rel field from the given pg_class tuple.
   */
  static Relation
  AllocateRelationDesc(Form_pg_class relp)
  {
  	Relation	relation;
  	MemoryContext oldcxt;
  	Form_pg_class relationForm;
  
  	/* Relcache entries must live in CacheMemoryContext */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  
  	/*
  	 * allocate and zero space for new relation descriptor
  	 */
  	relation = (Relation) palloc0(sizeof(RelationData));
  
  	/* make sure relation is marked as having no open file yet */
  	relation->rd_smgr = NULL;
  
  	/*
  	 * Copy the relation tuple form
  	 *
  	 * We only allocate space for the fixed fields, ie, CLASS_TUPLE_SIZE. The
  	 * variable-length fields (relacl, reloptions) are NOT stored in the
  	 * relcache --- there'd be little point in it, since we don't copy the
  	 * tuple's nulls bitmap and hence wouldn't know if the values are valid.
  	 * Bottom line is that relacl *cannot* be retrieved from the relcache. Get
  	 * it from the syscache if you need it.  The same goes for the original
  	 * form of reloptions (however, we do store the parsed form of reloptions
  	 * in rd_options).
  	 */
  	relationForm = (Form_pg_class) palloc(CLASS_TUPLE_SIZE);
  
  	memcpy(relationForm, relp, CLASS_TUPLE_SIZE);
  
  	/* initialize relation tuple form */
  	relation->rd_rel = relationForm;
  
  	/* and allocate attribute tuple form storage */
  	relation->rd_att = CreateTemplateTupleDesc(relationForm->relnatts);
  	/* which we mark as a reference-counted tupdesc */
  	relation->rd_att->tdrefcount = 1;
  
  	MemoryContextSwitchTo(oldcxt);
  
  	return relation;
  }
  
  /*
   * RelationParseRelOptions
   *		Convert pg_class.reloptions into pre-parsed rd_options
   *
   * tuple is the real pg_class tuple (not rd_rel!) for relation
   *
   * Note: rd_rel and (if an index) rd_indam must be valid already
   */
  static void
  RelationParseRelOptions(Relation relation, HeapTuple tuple)
  {
  	bytea	   *options;
  	amoptions_function amoptsfn;
  
  	relation->rd_options = NULL;
  
  	/*
  	 * Look up any AM-specific parse function; fall out if relkind should not
  	 * have options.
  	 */
  	switch (relation->rd_rel->relkind)
  	{
  		case RELKIND_RELATION:
  		case RELKIND_TOASTVALUE:
  		case RELKIND_VIEW:
  		case RELKIND_MATVIEW:
  		case RELKIND_PARTITIONED_TABLE:
  			amoptsfn = NULL;
  			break;
  		case RELKIND_INDEX:
  		case RELKIND_PARTITIONED_INDEX:
  			amoptsfn = relation->rd_indam->amoptions;
  			break;
  		default:
  			return;
  	}
  
  	/*
  	 * Fetch reloptions from tuple; have to use a hardwired descriptor because
  	 * we might not have any other for pg_class yet (consider executing this
  	 * code for pg_class itself)
  	 */
  	options = extractRelOptions(tuple, GetPgClassDescriptor(), amoptsfn);
  
  	/*
  	 * Copy parsed data into CacheMemoryContext.  To guard against the
  	 * possibility of leaks in the reloptions code, we want to do the actual
  	 * parsing in the caller's memory context and copy the results into
  	 * CacheMemoryContext after the fact.
  	 */
  	if (options)
  	{
  		relation->rd_options = MemoryContextAlloc(CacheMemoryContext,
  												  VARSIZE(options));
  		memcpy(relation->rd_options, options, VARSIZE(options));
  		pfree(options);
  	}
  }
  
  /*
   *		RelationBuildTupleDesc
   *
   *		Form the relation's tuple descriptor from information in
   *		the pg_attribute, pg_attrdef & pg_constraint system catalogs.
   */
  static void
  RelationBuildTupleDesc(Relation relation)
  {
  	HeapTuple	pg_attribute_tuple;
  	Relation	pg_attribute_desc;
  	SysScanDesc pg_attribute_scan;
  	ScanKeyData skey[2];
  	int			need;
  	TupleConstr *constr;
  	AttrMissing *attrmiss = NULL;
  	int			ndef = 0;
  
  	/* fill rd_att's type ID fields (compare heap.c's AddNewRelationTuple) */
  	relation->rd_att->tdtypeid =
  		relation->rd_rel->reltype ? relation->rd_rel->reltype : RECORDOID;
  	relation->rd_att->tdtypmod = -1;	/* just to be sure */
  
  	constr = (TupleConstr *) MemoryContextAllocZero(CacheMemoryContext,
  													sizeof(TupleConstr));
  	constr->has_not_null = false;
  	constr->has_generated_stored = false;
  
  	/*
  	 * Form a scan key that selects only user attributes (attnum > 0).
  	 * (Eliminating system attribute rows at the index level is lots faster
  	 * than fetching them.)
  	 */
  	ScanKeyInit(&skey[0],
  				Anum_pg_attribute_attrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  	ScanKeyInit(&skey[1],
  				Anum_pg_attribute_attnum,
  				BTGreaterStrategyNumber, F_INT2GT,
  				Int16GetDatum(0));
  
  	/*
  	 * Open pg_attribute and begin a scan.  Force heap scan if we haven't yet
  	 * built the critical relcache entries (this includes initdb and startup
  	 * without a pg_internal.init file).
  	 */
  	pg_attribute_desc = table_open(AttributeRelationId, AccessShareLock);
  	pg_attribute_scan = systable_beginscan(pg_attribute_desc,
  										   AttributeRelidNumIndexId,
  										   criticalRelcachesBuilt,
  										   NULL,
  										   2, skey);
  
  	/*
  	 * add attribute data to relation->rd_att
  	 */
  	need = RelationGetNumberOfAttributes(relation);
  
  	while (HeapTupleIsValid(pg_attribute_tuple = systable_getnext(pg_attribute_scan)))
  	{
  		Form_pg_attribute attp;
  		int			attnum;
  
  		attp = (Form_pg_attribute) GETSTRUCT(pg_attribute_tuple);
  
  		attnum = attp->attnum;
  		if (attnum <= 0 || attnum > RelationGetNumberOfAttributes(relation))
  			elog(ERROR, "invalid attribute number %d for relation \"%s\"",
  				 attp->attnum, RelationGetRelationName(relation));
  
  		memcpy(TupleDescAttr(relation->rd_att, attnum - 1),
  			   attp,
  			   ATTRIBUTE_FIXED_PART_SIZE);
  
  		/* Update constraint/default info */
  		if (attp->attnotnull)
  			constr->has_not_null = true;
  		if (attp->attgenerated == ATTRIBUTE_GENERATED_STORED)
  			constr->has_generated_stored = true;
  		if (attp->atthasdef)
  			ndef++;
  
  		/* If the column has a "missing" value, put it in the attrmiss array */
  		if (attp->atthasmissing)
  		{
  			Datum		missingval;
  			bool		missingNull;
  
  			/* Do we have a missing value? */
  			missingval = heap_getattr(pg_attribute_tuple,
  									  Anum_pg_attribute_attmissingval,
  									  pg_attribute_desc->rd_att,
  									  &missingNull);
  			if (!missingNull)
  			{
  				/* Yes, fetch from the array */
  				MemoryContext oldcxt;
  				bool		is_null;
  				int			one = 1;
  				Datum		missval;
  
  				if (attrmiss == NULL)
  					attrmiss = (AttrMissing *)
  						MemoryContextAllocZero(CacheMemoryContext,
  											   relation->rd_rel->relnatts *
  											   sizeof(AttrMissing));
  
  				missval = array_get_element(missingval,
  											1,
  											&one,
  											-1,
  											attp->attlen,
  											attp->attbyval,
  											attp->attalign,
  											&is_null);
  				Assert(!is_null);
  				if (attp->attbyval)
  				{
  					/* for copy by val just copy the datum direct */
  					attrmiss[attnum - 1].am_value = missval;
  				}
  				else
  				{
  					/* otherwise copy in the correct context */
  					oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  					attrmiss[attnum - 1].am_value = datumCopy(missval,
  															  attp->attbyval,
  															  attp->attlen);
  					MemoryContextSwitchTo(oldcxt);
  				}
  				attrmiss[attnum - 1].am_present = true;
  			}
  		}
  		need--;
  		if (need == 0)
  			break;
  	}
  
  	/*
  	 * end the scan and close the attribute relation
  	 */
  	systable_endscan(pg_attribute_scan);
  	table_close(pg_attribute_desc, AccessShareLock);
  
  	if (need != 0)
  		elog(ERROR, "pg_attribute catalog is missing %d attribute(s) for relation OID %u",
  			 need, RelationGetRelid(relation));
  
  	/*
  	 * The attcacheoff values we read from pg_attribute should all be -1
  	 * ("unknown").  Verify this if assert checking is on.  They will be
  	 * computed when and if needed during tuple access.
  	 */
  #ifdef USE_ASSERT_CHECKING
  	{
  		int			i;
  
  		for (i = 0; i < RelationGetNumberOfAttributes(relation); i++)
  			Assert(TupleDescAttr(relation->rd_att, i)->attcacheoff == -1);
  	}
  #endif
  
  	/*
  	 * However, we can easily set the attcacheoff value for the first
  	 * attribute: it must be zero.  This eliminates the need for special cases
  	 * for attnum=1 that used to exist in fastgetattr() and index_getattr().
  	 */
  	if (RelationGetNumberOfAttributes(relation) > 0)
  		TupleDescAttr(relation->rd_att, 0)->attcacheoff = 0;
  
  	/*
  	 * Set up constraint/default info
  	 */
  	if (constr->has_not_null ||
  		constr->has_generated_stored ||
  		ndef > 0 ||
  		attrmiss ||
  		relation->rd_rel->relchecks > 0)
  	{
  		relation->rd_att->constr = constr;
  
  		if (ndef > 0)			/* DEFAULTs */
  			AttrDefaultFetch(relation, ndef);
  		else
  			constr->num_defval = 0;
  
  		constr->missing = attrmiss;
  
  		if (relation->rd_rel->relchecks > 0)	/* CHECKs */
  			CheckConstraintFetch(relation);
  		else
  			constr->num_check = 0;
  	}
  	else
  	{
  		pfree(constr);
  		relation->rd_att->constr = NULL;
  	}
  }
  
  /*
   *		RelationBuildRuleLock
   *
   *		Form the relation's rewrite rules from information in
   *		the pg_rewrite system catalog.
   *
   * Note: The rule parsetrees are potentially very complex node structures.
   * To allow these trees to be freed when the relcache entry is flushed,
   * we make a private memory context to hold the RuleLock information for
   * each relcache entry that has associated rules.  The context is used
   * just for rule info, not for any other subsidiary data of the relcache
   * entry, because that keeps the update logic in RelationClearRelation()
   * manageable.  The other subsidiary data structures are simple enough
   * to be easy to free explicitly, anyway.
   */
  static void
  RelationBuildRuleLock(Relation relation)
  {
  	MemoryContext rulescxt;
  	MemoryContext oldcxt;
  	HeapTuple	rewrite_tuple;
  	Relation	rewrite_desc;
  	TupleDesc	rewrite_tupdesc;
  	SysScanDesc rewrite_scan;
  	ScanKeyData key;
  	RuleLock   *rulelock;
  	int			numlocks;
  	RewriteRule **rules;
  	int			maxlocks;
  
  	/*
  	 * Make the private context.  Assume it'll not contain much data.
  	 */
  	rulescxt = AllocSetContextCreate(CacheMemoryContext,
  									 "relation rules",
  									 ALLOCSET_SMALL_SIZES);
  	relation->rd_rulescxt = rulescxt;
  	MemoryContextCopyAndSetIdentifier(rulescxt,
  									  RelationGetRelationName(relation));
  
  	/*
  	 * allocate an array to hold the rewrite rules (the array is extended if
  	 * necessary)
  	 */
  	maxlocks = 4;
  	rules = (RewriteRule **)
  		MemoryContextAlloc(rulescxt, sizeof(RewriteRule *) * maxlocks);
  	numlocks = 0;
  
  	/*
  	 * form a scan key
  	 */
  	ScanKeyInit(&key,
  				Anum_pg_rewrite_ev_class,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	/*
  	 * open pg_rewrite and begin a scan
  	 *
  	 * Note: since we scan the rules using RewriteRelRulenameIndexId, we will
  	 * be reading the rules in name order, except possibly during
  	 * emergency-recovery operations (ie, IgnoreSystemIndexes). This in turn
  	 * ensures that rules will be fired in name order.
  	 */
  	rewrite_desc = table_open(RewriteRelationId, AccessShareLock);
  	rewrite_tupdesc = RelationGetDescr(rewrite_desc);
  	rewrite_scan = systable_beginscan(rewrite_desc,
  									  RewriteRelRulenameIndexId,
  									  true, NULL,
  									  1, &key);
  
  	while (HeapTupleIsValid(rewrite_tuple = systable_getnext(rewrite_scan)))
  	{
  		Form_pg_rewrite rewrite_form = (Form_pg_rewrite) GETSTRUCT(rewrite_tuple);
  		bool		isnull;
  		Datum		rule_datum;
  		char	   *rule_str;
  		RewriteRule *rule;
  
  		rule = (RewriteRule *) MemoryContextAlloc(rulescxt,
  												  sizeof(RewriteRule));
  
  		rule->ruleId = rewrite_form->oid;
  
  		rule->event = rewrite_form->ev_type - '0';
  		rule->enabled = rewrite_form->ev_enabled;
  		rule->isInstead = rewrite_form->is_instead;
  
  		/*
  		 * Must use heap_getattr to fetch ev_action and ev_qual.  Also, the
  		 * rule strings are often large enough to be toasted.  To avoid
  		 * leaking memory in the caller's context, do the detoasting here so
  		 * we can free the detoasted version.
  		 */
  		rule_datum = heap_getattr(rewrite_tuple,
  								  Anum_pg_rewrite_ev_action,
  								  rewrite_tupdesc,
  								  &isnull);
  		Assert(!isnull);
  		rule_str = TextDatumGetCString(rule_datum);
  		oldcxt = MemoryContextSwitchTo(rulescxt);
  		rule->actions = (List *) stringToNode(rule_str);
  		MemoryContextSwitchTo(oldcxt);
  		pfree(rule_str);
  
  		rule_datum = heap_getattr(rewrite_tuple,
  								  Anum_pg_rewrite_ev_qual,
  								  rewrite_tupdesc,
  								  &isnull);
  		Assert(!isnull);
  		rule_str = TextDatumGetCString(rule_datum);
  		oldcxt = MemoryContextSwitchTo(rulescxt);
  		rule->qual = (Node *) stringToNode(rule_str);
  		MemoryContextSwitchTo(oldcxt);
  		pfree(rule_str);
  
  		/*
  		 * We want the rule's table references to be checked as though by the
  		 * table owner, not the user referencing the rule.  Therefore, scan
  		 * through the rule's actions and set the checkAsUser field on all
  		 * rtable entries.  We have to look at the qual as well, in case it
  		 * contains sublinks.
  		 *
  		 * The reason for doing this when the rule is loaded, rather than when
  		 * it is stored, is that otherwise ALTER TABLE OWNER would have to
  		 * grovel through stored rules to update checkAsUser fields. Scanning
  		 * the rule tree during load is relatively cheap (compared to
  		 * constructing it in the first place), so we do it here.
  		 */
  		setRuleCheckAsUser((Node *) rule->actions, relation->rd_rel->relowner);
  		setRuleCheckAsUser(rule->qual, relation->rd_rel->relowner);
  
  		if (numlocks >= maxlocks)
  		{
  			maxlocks *= 2;
  			rules = (RewriteRule **)
  				repalloc(rules, sizeof(RewriteRule *) * maxlocks);
  		}
  		rules[numlocks++] = rule;
  	}
  
  	/*
  	 * end the scan and close the attribute relation
  	 */
  	systable_endscan(rewrite_scan);
  	table_close(rewrite_desc, AccessShareLock);
  
  	/*
  	 * there might not be any rules (if relhasrules is out-of-date)
  	 */
  	if (numlocks == 0)
  	{
  		relation->rd_rules = NULL;
  		relation->rd_rulescxt = NULL;
  		MemoryContextDelete(rulescxt);
  		return;
  	}
  
  	/*
  	 * form a RuleLock and insert into relation
  	 */
  	rulelock = (RuleLock *) MemoryContextAlloc(rulescxt, sizeof(RuleLock));
  	rulelock->numLocks = numlocks;
  	rulelock->rules = rules;
  
  	relation->rd_rules = rulelock;
  }
  
  /*
   *		equalRuleLocks
   *
   *		Determine whether two RuleLocks are equivalent
   *
   *		Probably this should be in the rules code someplace...
   */
  static bool
  equalRuleLocks(RuleLock *rlock1, RuleLock *rlock2)
  {
  	int			i;
  
  	/*
  	 * As of 7.3 we assume the rule ordering is repeatable, because
  	 * RelationBuildRuleLock should read 'em in a consistent order.  So just
  	 * compare corresponding slots.
  	 */
  	if (rlock1 != NULL)
  	{
  		if (rlock2 == NULL)
  			return false;
  		if (rlock1->numLocks != rlock2->numLocks)
  			return false;
  		for (i = 0; i < rlock1->numLocks; i++)
  		{
  			RewriteRule *rule1 = rlock1->rules[i];
  			RewriteRule *rule2 = rlock2->rules[i];
  
  			if (rule1->ruleId != rule2->ruleId)
  				return false;
  			if (rule1->event != rule2->event)
  				return false;
  			if (rule1->enabled != rule2->enabled)
  				return false;
  			if (rule1->isInstead != rule2->isInstead)
  				return false;
  			if (!equal(rule1->qual, rule2->qual))
  				return false;
  			if (!equal(rule1->actions, rule2->actions))
  				return false;
  		}
  	}
  	else if (rlock2 != NULL)
  		return false;
  	return true;
  }
  
  /*
   *		equalPolicy
   *
   *		Determine whether two policies are equivalent
   */
  static bool
  equalPolicy(RowSecurityPolicy *policy1, RowSecurityPolicy *policy2)
  {
  	int			i;
  	Oid		   *r1,
  			   *r2;
  
  	if (policy1 != NULL)
  	{
  		if (policy2 == NULL)
  			return false;
  
  		if (policy1->polcmd != policy2->polcmd)
  			return false;
  		if (policy1->hassublinks != policy2->hassublinks)
  			return false;
  		if (strcmp(policy1->policy_name, policy2->policy_name) != 0)
  			return false;
  		if (ARR_DIMS(policy1->roles)[0] != ARR_DIMS(policy2->roles)[0])
  			return false;
  
  		r1 = (Oid *) ARR_DATA_PTR(policy1->roles);
  		r2 = (Oid *) ARR_DATA_PTR(policy2->roles);
  
  		for (i = 0; i < ARR_DIMS(policy1->roles)[0]; i++)
  		{
  			if (r1[i] != r2[i])
  				return false;
  		}
  
  		if (!equal(policy1->qual, policy2->qual))
  			return false;
  		if (!equal(policy1->with_check_qual, policy2->with_check_qual))
  			return false;
  	}
  	else if (policy2 != NULL)
  		return false;
  
  	return true;
  }
  
  /*
   *		equalRSDesc
   *
   *		Determine whether two RowSecurityDesc's are equivalent
   */
  static bool
  equalRSDesc(RowSecurityDesc *rsdesc1, RowSecurityDesc *rsdesc2)
  {
  	ListCell   *lc,
  			   *rc;
  
  	if (rsdesc1 == NULL && rsdesc2 == NULL)
  		return true;
  
  	if ((rsdesc1 != NULL && rsdesc2 == NULL) ||
  		(rsdesc1 == NULL && rsdesc2 != NULL))
  		return false;
  
  	if (list_length(rsdesc1->policies) != list_length(rsdesc2->policies))
  		return false;
  
  	/* RelationBuildRowSecurity should build policies in order */
  	forboth(lc, rsdesc1->policies, rc, rsdesc2->policies)
  	{
  		RowSecurityPolicy *l = (RowSecurityPolicy *) lfirst(lc);
  		RowSecurityPolicy *r = (RowSecurityPolicy *) lfirst(rc);
  
  		if (!equalPolicy(l, r))
  			return false;
  	}
  
  	return true;
  }
  
  /*
   *		RelationBuildDesc
   *
   *		Build a relation descriptor.  The caller must hold at least
   *		AccessShareLock on the target relid.
   *
   *		The new descriptor is inserted into the hash table if insertIt is true.
   *
   *		Returns NULL if no pg_class row could be found for the given relid
   *		(suggesting we are trying to access a just-deleted relation).
   *		Any other error is reported via elog.
   */
  static Relation
  RelationBuildDesc(Oid targetRelId, bool insertIt)
  {
  	Relation	relation;
  	Oid			relid;
  	HeapTuple	pg_class_tuple;
  	Form_pg_class relp;
  
  	/*
  	 * This function and its subroutines can allocate a good deal of transient
  	 * data in CurrentMemoryContext.  Traditionally we've just leaked that
  	 * data, reasoning that the caller's context is at worst of transaction
  	 * scope, and relcache loads shouldn't happen so often that it's essential
  	 * to recover transient data before end of statement/transaction.  However
  	 * that's definitely not true in clobber-cache test builds, and perhaps
  	 * it's not true in other cases.
  	 *
  	 * When cache clobbering is enabled or when forced to by
  	 * RECOVER_RELATION_BUILD_MEMORY=1, arrange to allocate the junk in a
  	 * temporary context that we'll free before returning.  Make it a child of
  	 * caller's context so that it will get cleaned up appropriately if we
  	 * error out partway through.
  	 */
  #ifdef MAYBE_RECOVER_RELATION_BUILD_MEMORY
  	MemoryContext tmpcxt = NULL;
  	MemoryContext oldcxt = NULL;
  
  	if (RECOVER_RELATION_BUILD_MEMORY || debug_invalidate_system_caches_always > 0)
  	{
  		tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
  									   "RelationBuildDesc workspace",
  									   ALLOCSET_DEFAULT_SIZES);
  		oldcxt = MemoryContextSwitchTo(tmpcxt);
  	}
  #endif
  
  	/*
  	 * find the tuple in pg_class corresponding to the given relation id
  	 */
  	pg_class_tuple = ScanPgRelation(targetRelId, true, false);
  
  	/*
  	 * if no such tuple exists, return NULL
  	 */
  	if (!HeapTupleIsValid(pg_class_tuple))
  	{
  #ifdef MAYBE_RECOVER_RELATION_BUILD_MEMORY
  		if (tmpcxt)
  		{
  			/* Return to caller's context, and blow away the temporary context */
  			MemoryContextSwitchTo(oldcxt);
  			MemoryContextDelete(tmpcxt);
  		}
  #endif
  		return NULL;
  	}
  
  	/*
  	 * get information from the pg_class_tuple
  	 */
  	relp = (Form_pg_class) GETSTRUCT(pg_class_tuple);
  	relid = relp->oid;
  	Assert(relid == targetRelId);
  
  	/*
  	 * allocate storage for the relation descriptor, and copy pg_class_tuple
  	 * to relation->rd_rel.
  	 */
  	relation = AllocateRelationDesc(relp);
  
  	/*
  	 * initialize the relation's relation id (relation->rd_id)
  	 */
  	RelationGetRelid(relation) = relid;
  
  	/*
  	 * Normal relations are not nailed into the cache.  Since we don't flush
  	 * new relations, it won't be new.  It could be temp though.
  	 */
  	relation->rd_refcnt = 0;
  	relation->rd_isnailed = false;
  	relation->rd_createSubid = InvalidSubTransactionId;
  	relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  	relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  	relation->rd_droppedSubid = InvalidSubTransactionId;
  	switch (relation->rd_rel->relpersistence)
  	{
  		case RELPERSISTENCE_UNLOGGED:
  		case RELPERSISTENCE_PERMANENT:
  			relation->rd_backend = InvalidBackendId;
  			relation->rd_islocaltemp = false;
  			break;
  		case RELPERSISTENCE_TEMP:
  			if (isTempOrTempToastNamespace(relation->rd_rel->relnamespace))
  			{
  				relation->rd_backend = BackendIdForTempRelations();
  				relation->rd_islocaltemp = true;
  			}
  			else
  			{
  				/*
  				 * If it's a temp table, but not one of ours, we have to use
  				 * the slow, grotty method to figure out the owning backend.
  				 *
  				 * Note: it's possible that rd_backend gets set to MyBackendId
  				 * here, in case we are looking at a pg_class entry left over
  				 * from a crashed backend that coincidentally had the same
  				 * BackendId we're using.  We should *not* consider such a
  				 * table to be "ours"; this is why we need the separate
  				 * rd_islocaltemp flag.  The pg_class entry will get flushed
  				 * if/when we clean out the corresponding temp table namespace
  				 * in preparation for using it.
  				 */
  				relation->rd_backend =
  					GetTempNamespaceBackendId(relation->rd_rel->relnamespace);
  				Assert(relation->rd_backend != InvalidBackendId);
  				relation->rd_islocaltemp = false;
  			}
  			break;
  		default:
  			elog(ERROR, "invalid relpersistence: %c",
  				 relation->rd_rel->relpersistence);
  			break;
  	}
  
  	/*
  	 * initialize the tuple descriptor (relation->rd_att).
  	 */
  	RelationBuildTupleDesc(relation);
  
  	/*
  	 * Fetch rules and triggers that affect this relation
  	 */
  	if (relation->rd_rel->relhasrules)
  		RelationBuildRuleLock(relation);
  	else
  	{
  		relation->rd_rules = NULL;
  		relation->rd_rulescxt = NULL;
  	}
  
  	if (relation->rd_rel->relhastriggers)
  		RelationBuildTriggers(relation);
  	else
  		relation->trigdesc = NULL;
  
  	if (relation->rd_rel->relrowsecurity)
  		RelationBuildRowSecurity(relation);
  	else
  		relation->rd_rsdesc = NULL;
  
  	/* foreign key data is not loaded till asked for */
  	relation->rd_fkeylist = NIL;
  	relation->rd_fkeyvalid = false;
  
  	/* partitioning data is not loaded till asked for */
  	relation->rd_partkey = NULL;
  	relation->rd_partkeycxt = NULL;
  	relation->rd_partdesc = NULL;
  	relation->rd_partdesc_nodetached = NULL;
  	relation->rd_partdesc_nodetached_xmin = InvalidTransactionId;
  	relation->rd_pdcxt = NULL;
  	relation->rd_pddcxt = NULL;
  	relation->rd_partcheck = NIL;
  	relation->rd_partcheckvalid = false;
  	relation->rd_partcheckcxt = NULL;
  
  	/*
  	 * initialize access method information
  	 */
  	switch (relation->rd_rel->relkind)
  	{
  		case RELKIND_INDEX:
  		case RELKIND_PARTITIONED_INDEX:
  			Assert(relation->rd_rel->relam != InvalidOid);
  			RelationInitIndexAccessInfo(relation);
  			break;
  		case RELKIND_RELATION:
  		case RELKIND_TOASTVALUE:
  		case RELKIND_MATVIEW:
  			Assert(relation->rd_rel->relam != InvalidOid);
  			RelationInitTableAccessMethod(relation);
  			break;
  		case RELKIND_SEQUENCE:
  			Assert(relation->rd_rel->relam == InvalidOid);
  			RelationInitTableAccessMethod(relation);
  			break;
  		case RELKIND_VIEW:
  		case RELKIND_COMPOSITE_TYPE:
  		case RELKIND_FOREIGN_TABLE:
  		case RELKIND_PARTITIONED_TABLE:
  			Assert(relation->rd_rel->relam == InvalidOid);
  			break;
  	}
  
  #ifdef ADB
  	if (!singleuser)
  	{
  		if ((IsCnNode()||IsDnNode()) &&
  			relation->rd_id >= FirstNormalObjectId)
  			RelationBuildLocator(relation);
  
  		RelationBuildAuxiliary(relation);
  
  		RelationBuildExpansionClean(relation);
  	}
  #endif
  
  	/* extract reloptions if any */
  	RelationParseRelOptions(relation, pg_class_tuple);
  
  	/*
  	 * initialize the relation lock manager information
  	 */
  	RelationInitLockInfo(relation); /* see lmgr.c */
  
  	/*
  	 * initialize physical addressing information for the relation
  	 */
  	RelationInitPhysicalAddr(relation);
  
  	/* make sure relation is marked as having no open file yet */
  	relation->rd_smgr = NULL;
  
  	/*
  	 * now we can free the memory allocated for pg_class_tuple
  	 */
  	heap_freetuple(pg_class_tuple);
  
  	/*
  	 * Insert newly created relation into relcache hash table, if requested.
  	 *
  	 * There is one scenario in which we might find a hashtable entry already
  	 * present, even though our caller failed to find it: if the relation is a
  	 * system catalog or index that's used during relcache load, we might have
  	 * recursively created the same relcache entry during the preceding steps.
  	 * So allow RelationCacheInsert to delete any already-present relcache
  	 * entry for the same OID.  The already-present entry should have refcount
  	 * zero (else somebody forgot to close it); in the event that it doesn't,
  	 * we'll elog a WARNING and leak the already-present entry.
  	 */
  	if (insertIt)
  		RelationCacheInsert(relation, true);
  
  	/* It's fully valid */
  	relation->rd_isvalid = true;
  
  #ifdef MAYBE_RECOVER_RELATION_BUILD_MEMORY
  	if (tmpcxt)
  	{
  		/* Return to caller's context, and blow away the temporary context */
  		MemoryContextSwitchTo(oldcxt);
  		MemoryContextDelete(tmpcxt);
  	}
  #endif
  
  	return relation;
  }
  
  /*
   * Initialize the physical addressing info (RelFileNode) for a relcache entry
   *
   * Note: at the physical level, relations in the pg_global tablespace must
   * be treated as shared, even if relisshared isn't set.  Hence we do not
   * look at relisshared here.
   */
  static void
  RelationInitPhysicalAddr(Relation relation)
  {
  	Oid			oldnode = relation->rd_node.relNode;
  
  	/* these relations kinds never have storage */
  	if (!RELKIND_HAS_STORAGE(relation->rd_rel->relkind))
  		return;
  
  	if (relation->rd_rel->reltablespace)
  		relation->rd_node.spcNode = relation->rd_rel->reltablespace;
  	else
  		relation->rd_node.spcNode = MyDatabaseTableSpace;
  	if (relation->rd_node.spcNode == GLOBALTABLESPACE_OID)
  		relation->rd_node.dbNode = InvalidOid;
  	else
  		relation->rd_node.dbNode = MyDatabaseId;
  
  	if (relation->rd_rel->relfilenode)
  	{
  		/*
  		 * Even if we are using a decoding snapshot that doesn't represent the
  		 * current state of the catalog we need to make sure the filenode
  		 * points to the current file since the older file will be gone (or
  		 * truncated). The new file will still contain older rows so lookups
  		 * in them will work correctly. This wouldn't work correctly if
  		 * rewrites were allowed to change the schema in an incompatible way,
  		 * but those are prevented both on catalog tables and on user tables
  		 * declared as additional catalog tables.
  		 */
  		if (HistoricSnapshotActive()
  			&& RelationIsAccessibleInLogicalDecoding(relation)
  			&& IsTransactionState())
  		{
  			HeapTuple	phys_tuple;
  			Form_pg_class physrel;
  
  			phys_tuple = ScanPgRelation(RelationGetRelid(relation),
  										RelationGetRelid(relation) != ClassOidIndexId,
  										true);
  			if (!HeapTupleIsValid(phys_tuple))
  				elog(ERROR, "could not find pg_class entry for %u",
  					 RelationGetRelid(relation));
  			physrel = (Form_pg_class) GETSTRUCT(phys_tuple);
  
  			relation->rd_rel->reltablespace = physrel->reltablespace;
  			relation->rd_rel->relfilenode = physrel->relfilenode;
  			heap_freetuple(phys_tuple);
  		}
  
  		relation->rd_node.relNode = relation->rd_rel->relfilenode;
  	}
  	else
  	{
  		/* Consult the relation mapper */
  		relation->rd_node.relNode =
  			RelationMapOidToFilenode(relation->rd_id,
  									 relation->rd_rel->relisshared);
  		if (!OidIsValid(relation->rd_node.relNode))
  			elog(ERROR, "could not find relation mapping for relation \"%s\", OID %u",
  				 RelationGetRelationName(relation), relation->rd_id);
  	}
  
  	/*
  	 * For RelationNeedsWAL() to answer correctly on parallel workers, restore
  	 * rd_firstRelfilenodeSubid.  No subtransactions start or end while in
  	 * parallel mode, so the specific SubTransactionId does not matter.
  	 */
  	if (IsParallelWorker() && oldnode != relation->rd_node.relNode)
  	{
  		if (RelFileNodeSkippingWAL(relation->rd_node))
  			relation->rd_firstRelfilenodeSubid = TopSubTransactionId;
  		else
  			relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  	}
  }
  
  /*
   * Fill in the IndexAmRoutine for an index relation.
   *
   * relation's rd_amhandler and rd_indexcxt must be valid already.
   */
  static void
  InitIndexAmRoutine(Relation relation)
  {
  	IndexAmRoutine *cached,
  			   *tmp;
  
  	/*
  	 * Call the amhandler in current, short-lived memory context, just in case
  	 * it leaks anything (it probably won't, but let's be paranoid).
  	 */
  	tmp = GetIndexAmRoutine(relation->rd_amhandler);
  
  	/* OK, now transfer the data into relation's rd_indexcxt. */
  	cached = (IndexAmRoutine *) MemoryContextAlloc(relation->rd_indexcxt,
  												   sizeof(IndexAmRoutine));
  	memcpy(cached, tmp, sizeof(IndexAmRoutine));
  	relation->rd_indam = cached;
  
  	pfree(tmp);
  }
  
  /*
   * Initialize index-access-method support data for an index relation
   */
  void
  RelationInitIndexAccessInfo(Relation relation)
  {
  	HeapTuple	tuple;
  	Form_pg_am	aform;
  	Datum		indcollDatum;
  	Datum		indclassDatum;
  	Datum		indoptionDatum;
  	bool		isnull;
  	oidvector  *indcoll;
  	oidvector  *indclass;
  	int2vector *indoption;
  	MemoryContext indexcxt;
  	MemoryContext oldcontext;
  	int			indnatts;
  	int			indnkeyatts;
  	uint16		amsupport;
  
  	/*
  	 * Make a copy of the pg_index entry for the index.  Since pg_index
  	 * contains variable-length and possibly-null fields, we have to do this
  	 * honestly rather than just treating it as a Form_pg_index struct.
  	 */
  	tuple = SearchSysCache1(INDEXRELID,
  							ObjectIdGetDatum(RelationGetRelid(relation)));
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "cache lookup failed for index %u",
  			 RelationGetRelid(relation));
  	oldcontext = MemoryContextSwitchTo(CacheMemoryContext);
  	relation->rd_indextuple = heap_copytuple(tuple);
  	relation->rd_index = (Form_pg_index) GETSTRUCT(relation->rd_indextuple);
  	MemoryContextSwitchTo(oldcontext);
  	ReleaseSysCache(tuple);
  
  	/*
  	 * Look up the index's access method, save the OID of its handler function
  	 */
  	tuple = SearchSysCache1(AMOID, ObjectIdGetDatum(relation->rd_rel->relam));
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "cache lookup failed for access method %u",
  			 relation->rd_rel->relam);
  	aform = (Form_pg_am) GETSTRUCT(tuple);
  	relation->rd_amhandler = aform->amhandler;
  	ReleaseSysCache(tuple);
  
  	indnatts = RelationGetNumberOfAttributes(relation);
  	if (indnatts != IndexRelationGetNumberOfAttributes(relation))
  		elog(ERROR, "relnatts disagrees with indnatts for index %u",
  			 RelationGetRelid(relation));
  	indnkeyatts = IndexRelationGetNumberOfKeyAttributes(relation);
  
  	/*
  	 * Make the private context to hold index access info.  The reason we need
  	 * a context, and not just a couple of pallocs, is so that we won't leak
  	 * any subsidiary info attached to fmgr lookup records.
  	 */
  	indexcxt = AllocSetContextCreate(CacheMemoryContext,
  									 "index info",
  									 ALLOCSET_SMALL_SIZES);
  	relation->rd_indexcxt = indexcxt;
  	MemoryContextCopyAndSetIdentifier(indexcxt,
  									  RelationGetRelationName(relation));
  
  	/*
  	 * Now we can fetch the index AM's API struct
  	 */
  	InitIndexAmRoutine(relation);
  
  	/*
  	 * Allocate arrays to hold data. Opclasses are not used for included
  	 * columns, so allocate them for indnkeyatts only.
  	 */
  	relation->rd_opfamily = (Oid *)
  		MemoryContextAllocZero(indexcxt, indnkeyatts * sizeof(Oid));
  	relation->rd_opcintype = (Oid *)
  		MemoryContextAllocZero(indexcxt, indnkeyatts * sizeof(Oid));
  
  	amsupport = relation->rd_indam->amsupport;
  	if (amsupport > 0)
  	{
  		int			nsupport = indnatts * amsupport;
  
  		relation->rd_support = (RegProcedure *)
  			MemoryContextAllocZero(indexcxt, nsupport * sizeof(RegProcedure));
  		relation->rd_supportinfo = (FmgrInfo *)
  			MemoryContextAllocZero(indexcxt, nsupport * sizeof(FmgrInfo));
  	}
  	else
  	{
  		relation->rd_support = NULL;
  		relation->rd_supportinfo = NULL;
  	}
  
  	relation->rd_indcollation = (Oid *)
  		MemoryContextAllocZero(indexcxt, indnkeyatts * sizeof(Oid));
  
  	relation->rd_indoption = (int16 *)
  		MemoryContextAllocZero(indexcxt, indnkeyatts * sizeof(int16));
  
  	/*
  	 * indcollation cannot be referenced directly through the C struct,
  	 * because it comes after the variable-width indkey field.  Must extract
  	 * the datum the hard way...
  	 */
  	indcollDatum = fastgetattr(relation->rd_indextuple,
  							   Anum_pg_index_indcollation,
  							   GetPgIndexDescriptor(),
  							   &isnull);
  	Assert(!isnull);
  	indcoll = (oidvector *) DatumGetPointer(indcollDatum);
  	memcpy(relation->rd_indcollation, indcoll->values, indnkeyatts * sizeof(Oid));
  
  	/*
  	 * indclass cannot be referenced directly through the C struct, because it
  	 * comes after the variable-width indkey field.  Must extract the datum
  	 * the hard way...
  	 */
  	indclassDatum = fastgetattr(relation->rd_indextuple,
  								Anum_pg_index_indclass,
  								GetPgIndexDescriptor(),
  								&isnull);
  	Assert(!isnull);
  	indclass = (oidvector *) DatumGetPointer(indclassDatum);
  
  	/*
  	 * Fill the support procedure OID array, as well as the info about
  	 * opfamilies and opclass input types.  (aminfo and supportinfo are left
  	 * as zeroes, and are filled on-the-fly when used)
  	 */
  	IndexSupportInitialize(indclass, relation->rd_support,
  						   relation->rd_opfamily, relation->rd_opcintype,
  						   amsupport, indnkeyatts);
  
  	/*
  	 * Similarly extract indoption and copy it to the cache entry
  	 */
  	indoptionDatum = fastgetattr(relation->rd_indextuple,
  								 Anum_pg_index_indoption,
  								 GetPgIndexDescriptor(),
  								 &isnull);
  	Assert(!isnull);
  	indoption = (int2vector *) DatumGetPointer(indoptionDatum);
  	memcpy(relation->rd_indoption, indoption->values, indnkeyatts * sizeof(int16));
  
  	(void) RelationGetIndexAttOptions(relation, false);
  
  	/*
  	 * expressions, predicate, exclusion caches will be filled later
  	 */
  	relation->rd_indexprs = NIL;
  	relation->rd_indpred = NIL;
  	relation->rd_exclops = NULL;
  	relation->rd_exclprocs = NULL;
  	relation->rd_exclstrats = NULL;
  	relation->rd_amcache = NULL;
  }
  
  /*
   * IndexSupportInitialize
   *		Initializes an index's cached opclass information,
   *		given the index's pg_index.indclass entry.
   *
   * Data is returned into *indexSupport, *opFamily, and *opcInType,
   * which are arrays allocated by the caller.
   *
   * The caller also passes maxSupportNumber and maxAttributeNumber, since these
   * indicate the size of the arrays it has allocated --- but in practice these
   * numbers must always match those obtainable from the system catalog entries
   * for the index and access method.
   */
  static void
  IndexSupportInitialize(oidvector *indclass,
  					   RegProcedure *indexSupport,
  					   Oid *opFamily,
  					   Oid *opcInType,
  					   StrategyNumber maxSupportNumber,
  					   AttrNumber maxAttributeNumber)
  {
  	int			attIndex;
  
  	for (attIndex = 0; attIndex < maxAttributeNumber; attIndex++)
  	{
  		OpClassCacheEnt *opcentry;
  
  		if (!OidIsValid(indclass->values[attIndex]))
  			elog(ERROR, "bogus pg_index tuple");
  
  		/* look up the info for this opclass, using a cache */
  		opcentry = LookupOpclassInfo(indclass->values[attIndex],
  									 maxSupportNumber);
  
  		/* copy cached data into relcache entry */
  		opFamily[attIndex] = opcentry->opcfamily;
  		opcInType[attIndex] = opcentry->opcintype;
  		if (maxSupportNumber > 0)
  			memcpy(&indexSupport[attIndex * maxSupportNumber],
  				   opcentry->supportProcs,
  				   maxSupportNumber * sizeof(RegProcedure));
  	}
  }
  
  /*
   * LookupOpclassInfo
   *
   * This routine maintains a per-opclass cache of the information needed
   * by IndexSupportInitialize().  This is more efficient than relying on
   * the catalog cache, because we can load all the info about a particular
   * opclass in a single indexscan of pg_amproc.
   *
   * The information from pg_am about expected range of support function
   * numbers is passed in, rather than being looked up, mainly because the
   * caller will have it already.
   *
   * Note there is no provision for flushing the cache.  This is OK at the
   * moment because there is no way to ALTER any interesting properties of an
   * existing opclass --- all you can do is drop it, which will result in
   * a useless but harmless dead entry in the cache.  To support altering
   * opclass membership (not the same as opfamily membership!), we'd need to
   * be able to flush this cache as well as the contents of relcache entries
   * for indexes.
   */
  static OpClassCacheEnt *
  LookupOpclassInfo(Oid operatorClassOid,
  				  StrategyNumber numSupport)
  {
  	OpClassCacheEnt *opcentry;
  	bool		found;
  	Relation	rel;
  	SysScanDesc scan;
  	ScanKeyData skey[3];
  	HeapTuple	htup;
  	bool		indexOK;
  
  	if (OpClassCache == NULL)
  	{
  		/* First time through: initialize the opclass cache */
  		HASHCTL		ctl;
  
  		ctl.keysize = sizeof(Oid);
  		ctl.entrysize = sizeof(OpClassCacheEnt);
  		OpClassCache = hash_create("Operator class cache", 64,
  								   &ctl, HASH_ELEM | HASH_BLOBS);
  
  		/* Also make sure CacheMemoryContext exists */
  		if (!CacheMemoryContext)
  			CreateCacheMemoryContext();
  	}
  
  	opcentry = (OpClassCacheEnt *) hash_search(OpClassCache,
  											   (void *) &operatorClassOid,
  											   HASH_ENTER, &found);
  
  	if (!found)
  	{
  		/* Need to allocate memory for new entry */
  		opcentry->valid = false;	/* until known OK */
  		opcentry->numSupport = numSupport;
  
  		if (numSupport > 0)
  			opcentry->supportProcs = (RegProcedure *)
  				MemoryContextAllocZero(CacheMemoryContext,
  									   (numSupport + 1) * sizeof(RegProcedure));
  		else
  			opcentry->supportProcs = NULL;
  	}
  	else
  	{
  		Assert(numSupport == opcentry->numSupport);
  	}
  
  	/*
  	 * When testing for cache-flush hazards, we intentionally disable the
  	 * operator class cache and force reloading of the info on each call. This
  	 * is helpful because we want to test the case where a cache flush occurs
  	 * while we are loading the info, and it's very hard to provoke that if
  	 * this happens only once per opclass per backend.
  	 */
  #ifdef CLOBBER_CACHE_ENABLED
  	if (debug_invalidate_system_caches_always > 0)
  		opcentry->valid = false;
  #endif
  
  	if (opcentry->valid)
  		return opcentry;
  
  	/*
  	 * Need to fill in new entry.
  	 *
  	 * To avoid infinite recursion during startup, force heap scans if we're
  	 * looking up info for the opclasses used by the indexes we would like to
  	 * reference here.
  	 */
  	indexOK = criticalRelcachesBuilt ||
  		(operatorClassOid != OID_BTREE_OPS_OID &&
  		 operatorClassOid != INT2_BTREE_OPS_OID);
  
  	/*
  	 * We have to fetch the pg_opclass row to determine its opfamily and
  	 * opcintype, which are needed to look up related operators and functions.
  	 * It'd be convenient to use the syscache here, but that probably doesn't
  	 * work while bootstrapping.
  	 */
  	ScanKeyInit(&skey[0],
  				Anum_pg_opclass_oid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(operatorClassOid));
  	rel = table_open(OperatorClassRelationId, AccessShareLock);
  	scan = systable_beginscan(rel, OpclassOidIndexId, indexOK,
  							  NULL, 1, skey);
  
  	if (HeapTupleIsValid(htup = systable_getnext(scan)))
  	{
  		Form_pg_opclass opclassform = (Form_pg_opclass) GETSTRUCT(htup);
  
  		opcentry->opcfamily = opclassform->opcfamily;
  		opcentry->opcintype = opclassform->opcintype;
  	}
  	else
  		elog(ERROR, "could not find tuple for opclass %u", operatorClassOid);
  
  	systable_endscan(scan);
  	table_close(rel, AccessShareLock);
  
  	/*
  	 * Scan pg_amproc to obtain support procs for the opclass.  We only fetch
  	 * the default ones (those with lefttype = righttype = opcintype).
  	 */
  	if (numSupport > 0)
  	{
  		ScanKeyInit(&skey[0],
  					Anum_pg_amproc_amprocfamily,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(opcentry->opcfamily));
  		ScanKeyInit(&skey[1],
  					Anum_pg_amproc_amproclefttype,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(opcentry->opcintype));
  		ScanKeyInit(&skey[2],
  					Anum_pg_amproc_amprocrighttype,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(opcentry->opcintype));
  		rel = table_open(AccessMethodProcedureRelationId, AccessShareLock);
  		scan = systable_beginscan(rel, AccessMethodProcedureIndexId, indexOK,
  								  NULL, 3, skey);
  
  		while (HeapTupleIsValid(htup = systable_getnext(scan)))
  		{
  			Form_pg_amproc amprocform = (Form_pg_amproc) GETSTRUCT(htup);
  
  			if (amprocform->amprocnum <= 0 ||
  				(StrategyNumber) amprocform->amprocnum > numSupport)
  				elog(ERROR, "invalid amproc number %d for opclass %u",
  					 amprocform->amprocnum, operatorClassOid);
  
  			opcentry->supportProcs[amprocform->amprocnum - 1] =
  				amprocform->amproc;
  		}
  
  		systable_endscan(scan);
  		table_close(rel, AccessShareLock);
  	}
  
  	opcentry->valid = true;
  	return opcentry;
  }
  
  /*
   * Fill in the TableAmRoutine for a relation
   *
   * relation's rd_amhandler must be valid already.
   */
  static void
  InitTableAmRoutine(Relation relation)
  {
  	relation->rd_tableam = GetTableAmRoutine(relation->rd_amhandler);
  }
  
  /*
   * Initialize table access method support for a table like relation
   */
  void
  RelationInitTableAccessMethod(Relation relation)
  {
  	HeapTuple	tuple;
  	Form_pg_am	aform;
  
  	if (relation->rd_rel->relkind == RELKIND_SEQUENCE)
  	{
  		/*
  		 * Sequences are currently accessed like heap tables, but it doesn't
  		 * seem prudent to show that in the catalog. So just overwrite it
  		 * here.
  		 */
  		relation->rd_amhandler = F_HEAP_TABLEAM_HANDLER;
  	}
  	else if (IsCatalogRelation(relation))
  	{
  		/*
  		 * Avoid doing a syscache lookup for catalog tables.
  		 */
  		Assert(relation->rd_rel->relam == HEAP_TABLE_AM_OID);
  		relation->rd_amhandler = F_HEAP_TABLEAM_HANDLER;
  	}
  	else
  	{
  		/*
  		 * Look up the table access method, save the OID of its handler
  		 * function.
  		 */
  		Assert(relation->rd_rel->relam != InvalidOid);
  		tuple = SearchSysCache1(AMOID,
  								ObjectIdGetDatum(relation->rd_rel->relam));
  		if (!HeapTupleIsValid(tuple))
  			elog(ERROR, "cache lookup failed for access method %u",
  				 relation->rd_rel->relam);
  		aform = (Form_pg_am) GETSTRUCT(tuple);
  		relation->rd_amhandler = aform->amhandler;
  		ReleaseSysCache(tuple);
  	}
  
  	/*
  	 * Now we can fetch the table AM's API struct
  	 */
  	InitTableAmRoutine(relation);
  }
  
  /*
   *		formrdesc
   *
   *		This is a special cut-down version of RelationBuildDesc(),
   *		used while initializing the relcache.
   *		The relation descriptor is built just from the supplied parameters,
   *		without actually looking at any system table entries.  We cheat
   *		quite a lot since we only need to work for a few basic system
   *		catalogs.
   *
   * The catalogs this is used for can't have constraints (except attnotnull),
   * default values, rules, or triggers, since we don't cope with any of that.
   * (Well, actually, this only matters for properties that need to be valid
   * during bootstrap or before RelationCacheInitializePhase3 runs, and none of
   * these properties matter then...)
   *
   * NOTE: we assume we are already switched into CacheMemoryContext.
   */
  static void
  formrdesc(const char *relationName, Oid relationReltype,
  		  bool isshared,
  		  int natts, const FormData_pg_attribute *attrs)
  {
  	Relation	relation;
  	int			i;
  	bool		has_not_null;
  
  	/*
  	 * allocate new relation desc, clear all fields of reldesc
  	 */
  	relation = (Relation) palloc0(sizeof(RelationData));
  
  	/* make sure relation is marked as having no open file yet */
  	relation->rd_smgr = NULL;
  
  	/*
  	 * initialize reference count: 1 because it is nailed in cache
  	 */
  	relation->rd_refcnt = 1;
  
  	/*
  	 * all entries built with this routine are nailed-in-cache; none are for
  	 * new or temp relations.
  	 */
  	relation->rd_isnailed = true;
  	relation->rd_createSubid = InvalidSubTransactionId;
  	relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  	relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  	relation->rd_droppedSubid = InvalidSubTransactionId;
  	relation->rd_backend = InvalidBackendId;
  	relation->rd_islocaltemp = false;
  
  	/*
  	 * initialize relation tuple form
  	 *
  	 * The data we insert here is pretty incomplete/bogus, but it'll serve to
  	 * get us launched.  RelationCacheInitializePhase3() will read the real
  	 * data from pg_class and replace what we've done here.  Note in
  	 * particular that relowner is left as zero; this cues
  	 * RelationCacheInitializePhase3 that the real data isn't there yet.
  	 */
  	relation->rd_rel = (Form_pg_class) palloc0(CLASS_TUPLE_SIZE);
  
  	namestrcpy(&relation->rd_rel->relname, relationName);
  	relation->rd_rel->relnamespace = PG_CATALOG_NAMESPACE;
  	relation->rd_rel->reltype = relationReltype;
  
  	/*
  	 * It's important to distinguish between shared and non-shared relations,
  	 * even at bootstrap time, to make sure we know where they are stored.
  	 */
  	relation->rd_rel->relisshared = isshared;
  	if (isshared)
  		relation->rd_rel->reltablespace = GLOBALTABLESPACE_OID;
  
  	/* formrdesc is used only for permanent relations */
  	relation->rd_rel->relpersistence = RELPERSISTENCE_PERMANENT;
  
  	/* ... and they're always populated, too */
  	relation->rd_rel->relispopulated = true;
  
  	relation->rd_rel->relreplident = REPLICA_IDENTITY_NOTHING;
  	relation->rd_rel->relpages = 0;
  	relation->rd_rel->reltuples = -1;
  	relation->rd_rel->relallvisible = 0;
  	relation->rd_rel->relkind = RELKIND_RELATION;
  	relation->rd_rel->relnatts = (int16) natts;
  	relation->rd_rel->relam = HEAP_TABLE_AM_OID;
  
  	/*
  	 * initialize attribute tuple form
  	 *
  	 * Unlike the case with the relation tuple, this data had better be right
  	 * because it will never be replaced.  The data comes from
  	 * src/include/catalog/ headers via genbki.pl.
  	 */
  	relation->rd_att = CreateTemplateTupleDesc(natts);
  	relation->rd_att->tdrefcount = 1;	/* mark as refcounted */
  
  	relation->rd_att->tdtypeid = relationReltype;
  	relation->rd_att->tdtypmod = -1;	/* just to be sure */
  
  	/*
  	 * initialize tuple desc info
  	 */
  	has_not_null = false;
  	for (i = 0; i < natts; i++)
  	{
  		memcpy(TupleDescAttr(relation->rd_att, i),
  			   &attrs[i],
  			   ATTRIBUTE_FIXED_PART_SIZE);
  		has_not_null |= attrs[i].attnotnull;
  		/* make sure attcacheoff is valid */
  		TupleDescAttr(relation->rd_att, i)->attcacheoff = -1;
  	}
  
  	/* initialize first attribute's attcacheoff, cf RelationBuildTupleDesc */
  	TupleDescAttr(relation->rd_att, 0)->attcacheoff = 0;
  
  	/* mark not-null status */
  	if (has_not_null)
  	{
  		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
  
  		constr->has_not_null = true;
  		relation->rd_att->constr = constr;
  	}
  
  	/*
  	 * initialize relation id from info in att array (my, this is ugly)
  	 */
  	RelationGetRelid(relation) = TupleDescAttr(relation->rd_att, 0)->attrelid;
  
  	/*
  	 * All relations made with formrdesc are mapped.  This is necessarily so
  	 * because there is no other way to know what filenode they currently
  	 * have.  In bootstrap mode, add them to the initial relation mapper data,
  	 * specifying that the initial filenode is the same as the OID.
  	 */
  	relation->rd_rel->relfilenode = InvalidOid;
  	if (IsBootstrapProcessingMode())
  		RelationMapUpdateMap(RelationGetRelid(relation),
  							 RelationGetRelid(relation),
  							 isshared, true);
  
  	/*
  	 * initialize the relation lock manager information
  	 */
  	RelationInitLockInfo(relation); /* see lmgr.c */
  
  	/*
  	 * initialize physical addressing information for the relation
  	 */
  	RelationInitPhysicalAddr(relation);
  
  	/*
  	 * initialize the table am handler
  	 */
  	relation->rd_rel->relam = HEAP_TABLE_AM_OID;
  	relation->rd_tableam = GetHeapamTableAmRoutine();
  
  	/*
  	 * initialize the rel-has-index flag, using hardwired knowledge
  	 */
  	if (IsBootstrapProcessingMode())
  	{
  		/* In bootstrap mode, we have no indexes */
  		relation->rd_rel->relhasindex = false;
  	}
  	else
  	{
  		/* Otherwise, all the rels formrdesc is used for have indexes */
  		relation->rd_rel->relhasindex = true;
  	}
  
  	/*
  	 * add new reldesc to relcache
  	 */
  	RelationCacheInsert(relation, false);
  
  	/* It's fully valid */
  	relation->rd_isvalid = true;
  }
  
  
  /* ----------------------------------------------------------------
   *				 Relation Descriptor Lookup Interface
   * ----------------------------------------------------------------
   */
  
  /*
   *		RelationIdGetRelation
   *
   *		Lookup a reldesc by OID; make one if not already in cache.
   *
   *		Returns NULL if no pg_class row could be found for the given relid
   *		(suggesting we are trying to access a just-deleted relation).
   *		Any other error is reported via elog.
   *
   *		NB: caller should already have at least AccessShareLock on the
   *		relation ID, else there are nasty race conditions.
   *
   *		NB: relation ref count is incremented, or set to 1 if new entry.
   *		Caller should eventually decrement count.  (Usually,
   *		that happens by calling RelationClose().)
   */
  Relation
  RelationIdGetRelation(Oid relationId)
  {
  	Relation	rd;
  #ifdef ADB
  	List *masterNodeids = NIL;
  #endif
  
  	/* Make sure we're in an xact, even if this ends up being a cache hit */
  	Assert(IsTransactionState());
  
  	/*
  	 * first try to find reldesc in the cache
  	 */
  	RelationIdCacheLookup(relationId, rd);
  
  	if (RelationIsValid(rd))
  	{
  		/* return NULL for dropped relations */
  		if (rd->rd_droppedSubid != InvalidSubTransactionId)
  		{
  			Assert(!rd->rd_isvalid);
  			return NULL;
  		}
  
  		RelationIncrementReferenceCount(rd);
  		/* revalidate cache entry if necessary */
  		if (!rd->rd_isvalid)
  		{
  			/*
  			 * Indexes only have a limited number of possible schema changes,
  			 * and we don't want to use the full-blown procedure because it's
  			 * a headache for indexes that reload itself depends on.
  			 */
  			if (rd->rd_rel->relkind == RELKIND_INDEX ||
  				rd->rd_rel->relkind == RELKIND_PARTITIONED_INDEX)
  				RelationReloadIndexInfo(rd);
  			else
  				RelationClearRelation(rd, true);
  
  			/*
  			 * Normally entries need to be valid here, but before the relcache
  			 * has been initialized, not enough infrastructure exists to
  			 * perform pg_class lookups. The structure of such entries doesn't
  			 * change, but we still want to update the rd_rel entry. So
  			 * rd_isvalid = false is left in place for a later lookup.
  			 */
  			Assert(rd->rd_isvalid ||
  				   (rd->rd_isnailed && !criticalRelcachesBuilt));
  		}
  #ifdef ADB
  	}else{
  #else
  		return rd;
  	}
  #endif
  	/*
  	 * no reldesc in the cache, so have RelationBuildDesc() build one and add
  	 * it.
  	 */
  	rd = RelationBuildDesc(relationId, true);
  	if (RelationIsValid(rd))
  		RelationIncrementReferenceCount(rd);
  #ifdef ADB
  	}
  	if (!singleuser && rd && rd->rd_locator_info)
  	{
  		MemoryContext oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rd));
  		if (enable_readsql_on_slave && sql_readonly == SQLTYPE_READ)
  		{
  			if (rd->rd_locator_info->slavenodeids != NIL)
  				rd->rd_locator_info->nodeids = rd->rd_locator_info->slavenodeids;
  			else
  			{
  				masterNodeids = adbGetRelationNodeids(relationId);
  				rd->rd_locator_info->slavenodeids = adbUseDnSlaveNodeids(masterNodeids);
  				rd->rd_locator_info->nodeids = rd->rd_locator_info->slavenodeids;
  				if (masterNodeids)
  					list_free(masterNodeids);
  			}
  		}
  		else
  		{
  			if (rd->rd_locator_info->masternodeids)
  			{
  				rd->rd_locator_info->nodeids = rd->rd_locator_info->masternodeids;
  			}
  			else
  			{
  				rd->rd_locator_info->masternodeids = adbGetRelationNodeids(relationId);
  				rd->rd_locator_info->nodeids = rd->rd_locator_info->masternodeids;
  			}
  		}
  		MemoryContextSwitchTo(oldcontext);
  	}
  #endif
  	return rd;
  }
  
  /* ----------------------------------------------------------------
   *				cache invalidation support routines
   * ----------------------------------------------------------------
   */
  
  /*
   * RelationIncrementReferenceCount
   *		Increments relation reference count.
   *
   * Note: bootstrap mode has its own weird ideas about relation refcount
   * behavior; we ought to fix it someday, but for now, just disable
   * reference count ownership tracking in bootstrap mode.
   */
  void
  RelationIncrementReferenceCount(Relation rel)
  {
  	ResourceOwnerEnlargeRelationRefs(CurrentResourceOwner);
  	rel->rd_refcnt += 1;
  	if (!IsBootstrapProcessingMode())
  		ResourceOwnerRememberRelationRef(CurrentResourceOwner, rel);
  }
  
  /*
   * RelationDecrementReferenceCount
   *		Decrements relation reference count.
   */
  void
  RelationDecrementReferenceCount(Relation rel)
  {
  	Assert(rel->rd_refcnt > 0);
  	rel->rd_refcnt -= 1;
  	if (!IsBootstrapProcessingMode())
  		ResourceOwnerForgetRelationRef(CurrentResourceOwner, rel);
  }
  
  /*
   * RelationClose - close an open relation
   *
   *	Actually, we just decrement the refcount.
   *
   *	NOTE: if compiled with -DRELCACHE_FORCE_RELEASE then relcache entries
   *	will be freed as soon as their refcount goes to zero.  In combination
   *	with aset.c's CLOBBER_FREED_MEMORY option, this provides a good test
   *	to catch references to already-released relcache entries.  It slows
   *	things down quite a bit, however.
   */
  void
  RelationClose(Relation relation)
  {
  	/* Note: no locking manipulations needed */
  	RelationDecrementReferenceCount(relation);
  
  	/*
  	 * If the relation is no longer open in this session, we can clean up any
  	 * stale partition descriptors it has.  This is unlikely, so check to see
  	 * if there are child contexts before expending a call to mcxt.c.
  	 */
  	if (RelationHasReferenceCountZero(relation))
  	{
  		if (relation->rd_pdcxt != NULL &&
  			relation->rd_pdcxt->firstchild != NULL)
  			MemoryContextDeleteChildren(relation->rd_pdcxt);
  
  		if (relation->rd_pddcxt != NULL &&
  			relation->rd_pddcxt->firstchild != NULL)
  			MemoryContextDeleteChildren(relation->rd_pddcxt);
  	}
  
  #ifdef RELCACHE_FORCE_RELEASE
  	if (RelationHasReferenceCountZero(relation) &&
  		relation->rd_createSubid == InvalidSubTransactionId &&
  		relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)
  		RelationClearRelation(relation, false);
  #endif
  }
  
  /*
   * RelationReloadIndexInfo - reload minimal information for an open index
   *
   *	This function is used only for indexes.  A relcache inval on an index
   *	can mean that its pg_class or pg_index row changed.  There are only
   *	very limited changes that are allowed to an existing index's schema,
   *	so we can update the relcache entry without a complete rebuild; which
   *	is fortunate because we can't rebuild an index entry that is "nailed"
   *	and/or in active use.  We support full replacement of the pg_class row,
   *	as well as updates of a few simple fields of the pg_index row.
   *
   *	We can't necessarily reread the catalog rows right away; we might be
   *	in a failed transaction when we receive the SI notification.  If so,
   *	RelationClearRelation just marks the entry as invalid by setting
   *	rd_isvalid to false.  This routine is called to fix the entry when it
   *	is next needed.
   *
   *	We assume that at the time we are called, we have at least AccessShareLock
   *	on the target index.  (Note: in the calls from RelationClearRelation,
   *	this is legitimate because we know the rel has positive refcount.)
   *
   *	If the target index is an index on pg_class or pg_index, we'd better have
   *	previously gotten at least AccessShareLock on its underlying catalog,
   *	else we are at risk of deadlock against someone trying to exclusive-lock
   *	the heap and index in that order.  This is ensured in current usage by
   *	only applying this to indexes being opened or having positive refcount.
   */
  static void
  RelationReloadIndexInfo(Relation relation)
  {
  	bool		indexOK;
  	HeapTuple	pg_class_tuple;
  	Form_pg_class relp;
  
  	/* Should be called only for invalidated, live indexes */
  	Assert((relation->rd_rel->relkind == RELKIND_INDEX ||
  			relation->rd_rel->relkind == RELKIND_PARTITIONED_INDEX) &&
  		   !relation->rd_isvalid &&
  		   relation->rd_droppedSubid == InvalidSubTransactionId);
  
  	/* Ensure it's closed at smgr level */
  	RelationCloseSmgr(relation);
  
  	/* Must free any AM cached data upon relcache flush */
  	if (relation->rd_amcache)
  		pfree(relation->rd_amcache);
  	relation->rd_amcache = NULL;
  
  	/*
  	 * If it's a shared index, we might be called before backend startup has
  	 * finished selecting a database, in which case we have no way to read
  	 * pg_class yet.  However, a shared index can never have any significant
  	 * schema updates, so it's okay to ignore the invalidation signal.  Just
  	 * mark it valid and return without doing anything more.
  	 */
  	if (relation->rd_rel->relisshared && !criticalRelcachesBuilt)
  	{
  		relation->rd_isvalid = true;
  		return;
  	}
  
  	/*
  	 * Read the pg_class row
  	 *
  	 * Don't try to use an indexscan of pg_class_oid_index to reload the info
  	 * for pg_class_oid_index ...
  	 */
  	indexOK = (RelationGetRelid(relation) != ClassOidIndexId);
  	pg_class_tuple = ScanPgRelation(RelationGetRelid(relation), indexOK, false);
  	if (!HeapTupleIsValid(pg_class_tuple))
  		elog(ERROR, "could not find pg_class tuple for index %u",
  			 RelationGetRelid(relation));
  	relp = (Form_pg_class) GETSTRUCT(pg_class_tuple);
  	memcpy(relation->rd_rel, relp, CLASS_TUPLE_SIZE);
  	/* Reload reloptions in case they changed */
  	if (relation->rd_options)
  		pfree(relation->rd_options);
  	RelationParseRelOptions(relation, pg_class_tuple);
  	/* done with pg_class tuple */
  	heap_freetuple(pg_class_tuple);
  	/* We must recalculate physical address in case it changed */
  	RelationInitPhysicalAddr(relation);
  
  	/*
  	 * For a non-system index, there are fields of the pg_index row that are
  	 * allowed to change, so re-read that row and update the relcache entry.
  	 * Most of the info derived from pg_index (such as support function lookup
  	 * info) cannot change, and indeed the whole point of this routine is to
  	 * update the relcache entry without clobbering that data; so wholesale
  	 * replacement is not appropriate.
  	 */
  	if (!IsSystemRelation(relation))
  	{
  		HeapTuple	tuple;
  		Form_pg_index index;
  
  		tuple = SearchSysCache1(INDEXRELID,
  								ObjectIdGetDatum(RelationGetRelid(relation)));
  		if (!HeapTupleIsValid(tuple))
  			elog(ERROR, "cache lookup failed for index %u",
  				 RelationGetRelid(relation));
  		index = (Form_pg_index) GETSTRUCT(tuple);
  
  		/*
  		 * Basically, let's just copy all the bool fields.  There are one or
  		 * two of these that can't actually change in the current code, but
  		 * it's not worth it to track exactly which ones they are.  None of
  		 * the array fields are allowed to change, though.
  		 */
  		relation->rd_index->indisunique = index->indisunique;
  		relation->rd_index->indisprimary = index->indisprimary;
  		relation->rd_index->indisexclusion = index->indisexclusion;
  		relation->rd_index->indimmediate = index->indimmediate;
  		relation->rd_index->indisclustered = index->indisclustered;
  		relation->rd_index->indisvalid = index->indisvalid;
  		relation->rd_index->indcheckxmin = index->indcheckxmin;
  		relation->rd_index->indisready = index->indisready;
  		relation->rd_index->indislive = index->indislive;
  
  		/* Copy xmin too, as that is needed to make sense of indcheckxmin */
  		HeapTupleHeaderSetXmin(relation->rd_indextuple->t_data,
  							   HeapTupleHeaderGetXmin(tuple->t_data));
  
  		ReleaseSysCache(tuple);
  	}
  
  	/* Okay, now it's valid again */
  	relation->rd_isvalid = true;
  }
  
  /*
   * RelationReloadNailed - reload minimal information for nailed relations.
   *
   * The structure of a nailed relation can never change (which is good, because
   * we rely on knowing their structure to be able to read catalog content). But
   * some parts, e.g. pg_class.relfrozenxid, are still important to have
   * accurate content for. Therefore those need to be reloaded after the arrival
   * of invalidations.
   */
  static void
  RelationReloadNailed(Relation relation)
  {
  	Assert(relation->rd_isnailed);
  
  	/*
  	 * Redo RelationInitPhysicalAddr in case it is a mapped relation whose
  	 * mapping changed.
  	 */
  	RelationInitPhysicalAddr(relation);
  
  	/* flag as needing to be revalidated */
  	relation->rd_isvalid = false;
  
  	/*
  	 * Can only reread catalog contents if in a transaction.  If the relation
  	 * is currently open (not counting the nailed refcount), do so
  	 * immediately. Otherwise we've already marked the entry as possibly
  	 * invalid, and it'll be fixed when next opened.
  	 */
  	if (!IsTransactionState() || relation->rd_refcnt <= 1)
  		return;
  
  	if (relation->rd_rel->relkind == RELKIND_INDEX)
  	{
  		/*
  		 * If it's a nailed-but-not-mapped index, then we need to re-read the
  		 * pg_class row to see if its relfilenode changed.
  		 */
  		RelationReloadIndexInfo(relation);
  	}
  	else
  	{
  		/*
  		 * Reload a non-index entry.  We can't easily do so if relcaches
  		 * aren't yet built, but that's fine because at that stage the
  		 * attributes that need to be current (like relfrozenxid) aren't yet
  		 * accessed.  To ensure the entry will later be revalidated, we leave
  		 * it in invalid state, but allow use (cf. RelationIdGetRelation()).
  		 */
  		if (criticalRelcachesBuilt)
  		{
  			HeapTuple	pg_class_tuple;
  			Form_pg_class relp;
  
  			/*
  			 * NB: Mark the entry as valid before starting to scan, to avoid
  			 * self-recursion when re-building pg_class.
  			 */
  			relation->rd_isvalid = true;
  
  			pg_class_tuple = ScanPgRelation(RelationGetRelid(relation),
  											true, false);
  			relp = (Form_pg_class) GETSTRUCT(pg_class_tuple);
  			memcpy(relation->rd_rel, relp, CLASS_TUPLE_SIZE);
  			heap_freetuple(pg_class_tuple);
  
  			/*
  			 * Again mark as valid, to protect against concurrently arriving
  			 * invalidations.
  			 */
  			relation->rd_isvalid = true;
  		}
  	}
  }
  
  /*
   * RelationDestroyRelation
   *
   *	Physically delete a relation cache entry and all subsidiary data.
   *	Caller must already have unhooked the entry from the hash table.
   */
  static void
  RelationDestroyRelation(Relation relation, bool remember_tupdesc)
  {
  	Assert(RelationHasReferenceCountZero(relation));
  
  	/*
  	 * Make sure smgr and lower levels close the relation's files, if they
  	 * weren't closed already.  (This was probably done by caller, but let's
  	 * just be real sure.)
  	 */
  	RelationCloseSmgr(relation);
  
  	/*
  	 * Free all the subsidiary data structures of the relcache entry, then the
  	 * entry itself.
  	 */
  	if (relation->rd_rel)
  		pfree(relation->rd_rel);
  	/* can't use DecrTupleDescRefCount here */
  	Assert(relation->rd_att->tdrefcount > 0);
  	if (--relation->rd_att->tdrefcount == 0)
  	{
  		/*
  		 * If we Rebuilt a relcache entry during a transaction then its
  		 * possible we did that because the TupDesc changed as the result of
  		 * an ALTER TABLE that ran at less than AccessExclusiveLock. It's
  		 * possible someone copied that TupDesc, in which case the copy would
  		 * point to free'd memory. So if we rebuild an entry we keep the
  		 * TupDesc around until end of transaction, to be safe.
  		 */
  		if (remember_tupdesc)
  			RememberToFreeTupleDescAtEOX(relation->rd_att);
  		else
  			FreeTupleDesc(relation->rd_att);
  	}
  	FreeTriggerDesc(relation->trigdesc);
  	list_free_deep(relation->rd_fkeylist);
  	list_free(relation->rd_indexlist);
  	list_free(relation->rd_statlist);
  	bms_free(relation->rd_indexattr);
  	bms_free(relation->rd_keyattr);
  	bms_free(relation->rd_pkattr);
  	bms_free(relation->rd_idattr);
  	if (relation->rd_pubactions)
  		pfree(relation->rd_pubactions);
  	if (relation->rd_options)
  		pfree(relation->rd_options);
  	if (relation->rd_indextuple)
  		pfree(relation->rd_indextuple);
  	if (relation->rd_amcache)
  		pfree(relation->rd_amcache);
  	if (relation->rd_fdwroutine)
  		pfree(relation->rd_fdwroutine);
  	if (relation->rd_indexcxt)
  		MemoryContextDelete(relation->rd_indexcxt);
  	if (relation->rd_rulescxt)
  		MemoryContextDelete(relation->rd_rulescxt);
  	if (relation->rd_rsdesc)
  		MemoryContextDelete(relation->rd_rsdesc->rscxt);
  	if (relation->rd_partkeycxt)
  		MemoryContextDelete(relation->rd_partkeycxt);
  	if (relation->rd_pdcxt)
  		MemoryContextDelete(relation->rd_pdcxt);
  	if (relation->rd_pddcxt)
  		MemoryContextDelete(relation->rd_pddcxt);
  	if (relation->rd_partcheckcxt)
  		MemoryContextDelete(relation->rd_partcheckcxt);
  #ifdef ADB
  	if (relation->rd_locator_info)
  	{
  		MemoryContext context = GetMemoryChunkContext(relation->rd_locator_info);
  		Assert(context != CacheMemoryContext);
  		MemoryContextDelete(context);
  	}
  	if (relation->rd_auxlist)
  		list_free(relation->rd_auxlist);
  	bms_free(relation->rd_auxatt);
  	if (relation->rd_clean)
  		DestroyExpansionClean(relation->rd_clean);
  #endif
  	pfree(relation);
  }
  
  /*
   * RelationClearRelation
   *
   *	 Physically blow away a relation cache entry, or reset it and rebuild
   *	 it from scratch (that is, from catalog entries).  The latter path is
   *	 used when we are notified of a change to an open relation (one with
   *	 refcount > 0).
   *
   *	 NB: when rebuilding, we'd better hold some lock on the relation,
   *	 else the catalog data we need to read could be changing under us.
   *	 Also, a rel to be rebuilt had better have refcnt > 0.  This is because
   *	 a sinval reset could happen while we're accessing the catalogs, and
   *	 the rel would get blown away underneath us by RelationCacheInvalidate
   *	 if it has zero refcnt.
   *
   *	 The "rebuild" parameter is redundant in current usage because it has
   *	 to match the relation's refcnt status, but we keep it as a crosscheck
   *	 that we're doing what the caller expects.
   */
  static void
  RelationClearRelation(Relation relation, bool rebuild)
  {
  	/*
  	 * As per notes above, a rel to be rebuilt MUST have refcnt > 0; while of
  	 * course it would be an equally bad idea to blow away one with nonzero
  	 * refcnt, since that would leave someone somewhere with a dangling
  	 * pointer.  All callers are expected to have verified that this holds.
  	 */
  	Assert(rebuild ?
  		   !RelationHasReferenceCountZero(relation) :
  		   RelationHasReferenceCountZero(relation));
  
  	/*
  	 * Make sure smgr and lower levels close the relation's files, if they
  	 * weren't closed already.  If the relation is not getting deleted, the
  	 * next smgr access should reopen the files automatically.  This ensures
  	 * that the low-level file access state is updated after, say, a vacuum
  	 * truncation.
  	 */
  	RelationCloseSmgr(relation);
  
  	/* Free AM cached data, if any */
  	if (relation->rd_amcache)
  		pfree(relation->rd_amcache);
  	relation->rd_amcache = NULL;
  
  	/*
  	 * Treat nailed-in system relations separately, they always need to be
  	 * accessible, so we can't blow them away.
  	 */
  	if (relation->rd_isnailed)
  	{
  		RelationReloadNailed(relation);
  		return;
  	}
  
  	/* Mark it invalid until we've finished rebuild */
  	relation->rd_isvalid = false;
  
  	/* See RelationForgetRelation(). */
  	if (relation->rd_droppedSubid != InvalidSubTransactionId)
  		return;
  
  	/*
  	 * Even non-system indexes should not be blown away if they are open and
  	 * have valid index support information.  This avoids problems with active
  	 * use of the index support information.  As with nailed indexes, we
  	 * re-read the pg_class row to handle possible physical relocation of the
  	 * index, and we check for pg_index updates too.
  	 */
  	if ((relation->rd_rel->relkind == RELKIND_INDEX ||
  		 relation->rd_rel->relkind == RELKIND_PARTITIONED_INDEX) &&
  		relation->rd_refcnt > 0 &&
  		relation->rd_indexcxt != NULL)
  	{
  		if (IsTransactionState())
  			RelationReloadIndexInfo(relation);
  		return;
  	}
  
  	/*
  	 * If we're really done with the relcache entry, blow it away. But if
  	 * someone is still using it, reconstruct the whole deal without moving
  	 * the physical RelationData record (so that the someone's pointer is
  	 * still valid).
  	 */
  	if (!rebuild)
  	{
  		/* Remove it from the hash table */
  		RelationCacheDelete(relation);
  
  		/* And release storage */
  		RelationDestroyRelation(relation, false);
  	}
  	else if (!IsTransactionState())
  	{
  		/*
  		 * If we're not inside a valid transaction, we can't do any catalog
  		 * access so it's not possible to rebuild yet.  Just exit, leaving
  		 * rd_isvalid = false so that the rebuild will occur when the entry is
  		 * next opened.
  		 *
  		 * Note: it's possible that we come here during subtransaction abort,
  		 * and the reason for wanting to rebuild is that the rel is open in
  		 * the outer transaction.  In that case it might seem unsafe to not
  		 * rebuild immediately, since whatever code has the rel already open
  		 * will keep on using the relcache entry as-is.  However, in such a
  		 * case the outer transaction should be holding a lock that's
  		 * sufficient to prevent any significant change in the rel's schema,
  		 * so the existing entry contents should be good enough for its
  		 * purposes; at worst we might be behind on statistics updates or the
  		 * like.  (See also CheckTableNotInUse() and its callers.)	These same
  		 * remarks also apply to the cases above where we exit without having
  		 * done RelationReloadIndexInfo() yet.
  		 */
  		return;
  	}
  	else
  	{
  		/*
  		 * Our strategy for rebuilding an open relcache entry is to build a
  		 * new entry from scratch, swap its contents with the old entry, and
  		 * finally delete the new entry (along with any infrastructure swapped
  		 * over from the old entry).  This is to avoid trouble in case an
  		 * error causes us to lose control partway through.  The old entry
  		 * will still be marked !rd_isvalid, so we'll try to rebuild it again
  		 * on next access.  Meanwhile it's not any less valid than it was
  		 * before, so any code that might expect to continue accessing it
  		 * isn't hurt by the rebuild failure.  (Consider for example a
  		 * subtransaction that ALTERs a table and then gets canceled partway
  		 * through the cache entry rebuild.  The outer transaction should
  		 * still see the not-modified cache entry as valid.)  The worst
  		 * consequence of an error is leaking the necessarily-unreferenced new
  		 * entry, and this shouldn't happen often enough for that to be a big
  		 * problem.
  		 *
  		 * When rebuilding an open relcache entry, we must preserve ref count,
  		 * rd_*Subid, and rd_toastoid state.  Also attempt to preserve the
  		 * pg_class entry (rd_rel), tupledesc, rewrite-rule, partition key,
  		 * and partition descriptor substructures in place, because various
  		 * places assume that these structures won't move while they are
  		 * working with an open relcache entry.  (Note:  the refcount
  		 * mechanism for tupledescs might someday allow us to remove this hack
  		 * for the tupledesc.)
  		 *
  		 * Note that this process does not touch CurrentResourceOwner; which
  		 * is good because whatever ref counts the entry may have do not
  		 * necessarily belong to that resource owner.
  		 */
  		Relation	newrel;
  		Oid			save_relid = RelationGetRelid(relation);
  		bool		keep_tupdesc;
  		bool		keep_rules;
  		bool		keep_policies;
  		bool		keep_partkey;
  
  		/* Build temporary entry, but don't link it into hashtable */
  		newrel = RelationBuildDesc(save_relid, false);
  		if (newrel == NULL)
  		{
  			/*
  			 * We can validly get here, if we're using a historic snapshot in
  			 * which a relation, accessed from outside logical decoding, is
  			 * still invisible. In that case it's fine to just mark the
  			 * relation as invalid and return - it'll fully get reloaded by
  			 * the cache reset at the end of logical decoding (or at the next
  			 * access).  During normal processing we don't want to ignore this
  			 * case as it shouldn't happen there, as explained below.
  			 */
  			if (HistoricSnapshotActive())
  				return;
  
  			/*
  			 * This shouldn't happen as dropping a relation is intended to be
  			 * impossible if still referenced (cf. CheckTableNotInUse()). But
  			 * if we get here anyway, we can't just delete the relcache entry,
  			 * as it possibly could get accessed later (as e.g. the error
  			 * might get trapped and handled via a subtransaction rollback).
  			 */
  			elog(ERROR, "relation %u deleted while still in use", save_relid);
  		}
  
  		keep_tupdesc = equalTupleDescs(relation->rd_att, newrel->rd_att);
  		keep_rules = equalRuleLocks(relation->rd_rules, newrel->rd_rules);
  		keep_policies = equalRSDesc(relation->rd_rsdesc, newrel->rd_rsdesc);
  		/* partkey is immutable once set up, so we can always keep it */
  		keep_partkey = (relation->rd_partkey != NULL);
  
  		/*
  		 * Perform swapping of the relcache entry contents.  Within this
  		 * process the old entry is momentarily invalid, so there *must* be no
  		 * possibility of CHECK_FOR_INTERRUPTS within this sequence. Do it in
  		 * all-in-line code for safety.
  		 *
  		 * Since the vast majority of fields should be swapped, our method is
  		 * to swap the whole structures and then re-swap those few fields we
  		 * didn't want swapped.
  		 */
  #define SWAPFIELD(fldtype, fldname) \
  		do { \
  			fldtype _tmp = newrel->fldname; \
  			newrel->fldname = relation->fldname; \
  			relation->fldname = _tmp; \
  		} while (0)
  
  		/* swap all Relation struct fields */
  		{
  			RelationData tmpstruct;
  
  			memcpy(&tmpstruct, newrel, sizeof(RelationData));
  			memcpy(newrel, relation, sizeof(RelationData));
  			memcpy(relation, &tmpstruct, sizeof(RelationData));
  		}
  
  		/* rd_smgr must not be swapped, due to back-links from smgr level */
  		SWAPFIELD(SMgrRelation, rd_smgr);
  		/* rd_refcnt must be preserved */
  		SWAPFIELD(int, rd_refcnt);
  		/* isnailed shouldn't change */
  		Assert(newrel->rd_isnailed == relation->rd_isnailed);
  		/* creation sub-XIDs must be preserved */
  		SWAPFIELD(SubTransactionId, rd_createSubid);
  		SWAPFIELD(SubTransactionId, rd_newRelfilenodeSubid);
  		SWAPFIELD(SubTransactionId, rd_firstRelfilenodeSubid);
  		SWAPFIELD(SubTransactionId, rd_droppedSubid);
  		/* un-swap rd_rel pointers, swap contents instead */
  		SWAPFIELD(Form_pg_class, rd_rel);
  		/* ... but actually, we don't have to update newrel->rd_rel */
  		memcpy(relation->rd_rel, newrel->rd_rel, CLASS_TUPLE_SIZE);
  		/* preserve old tupledesc, rules, policies if no logical change */
  		if (keep_tupdesc)
  			SWAPFIELD(TupleDesc, rd_att);
  		if (keep_rules)
  		{
  			SWAPFIELD(RuleLock *, rd_rules);
  			SWAPFIELD(MemoryContext, rd_rulescxt);
  		}
  		if (keep_policies)
  			SWAPFIELD(RowSecurityDesc *, rd_rsdesc);
  		/* toast OID override must be preserved */
  		SWAPFIELD(Oid, rd_toastoid);
  		/* pgstat_info must be preserved */
  		SWAPFIELD(struct PgStat_TableStatus *, pgstat_info);
  		/* preserve old partition key if we have one */
  		if (keep_partkey)
  		{
  			SWAPFIELD(PartitionKey, rd_partkey);
  			SWAPFIELD(MemoryContext, rd_partkeycxt);
  		}
  		if (newrel->rd_pdcxt != NULL || newrel->rd_pddcxt != NULL)
  		{
  			/*
  			 * We are rebuilding a partitioned relation with a non-zero
  			 * reference count, so we must keep the old partition descriptor
  			 * around, in case there's a PartitionDirectory with a pointer to
  			 * it.  This means we can't free the old rd_pdcxt yet.  (This is
  			 * necessary because RelationGetPartitionDesc hands out direct
  			 * pointers to the relcache's data structure, unlike our usual
  			 * practice which is to hand out copies.  We'd have the same
  			 * problem with rd_partkey, except that we always preserve that
  			 * once created.)
  			 *
  			 * To ensure that it's not leaked completely, re-attach it to the
  			 * new reldesc, or make it a child of the new reldesc's rd_pdcxt
  			 * in the unlikely event that there is one already.  (Compare hack
  			 * in RelationBuildPartitionDesc.)  RelationClose will clean up
  			 * any such contexts once the reference count reaches zero.
  			 *
  			 * In the case where the reference count is zero, this code is not
  			 * reached, which should be OK because in that case there should
  			 * be no PartitionDirectory with a pointer to the old entry.
  			 *
  			 * Note that newrel and relation have already been swapped, so the
  			 * "old" partition descriptor is actually the one hanging off of
  			 * newrel.
  			 */
  			relation->rd_partdesc = NULL;	/* ensure rd_partdesc is invalid */
  			relation->rd_partdesc_nodetached = NULL;
  			relation->rd_partdesc_nodetached_xmin = InvalidTransactionId;
  			if (relation->rd_pdcxt != NULL) /* probably never happens */
  				MemoryContextSetParent(newrel->rd_pdcxt, relation->rd_pdcxt);
  			else
  				relation->rd_pdcxt = newrel->rd_pdcxt;
  			if (relation->rd_pddcxt != NULL)
  				MemoryContextSetParent(newrel->rd_pddcxt, relation->rd_pddcxt);
  			else
  				relation->rd_pddcxt = newrel->rd_pddcxt;
  			/* drop newrel's pointers so we don't destroy it below */
  			newrel->rd_partdesc = NULL;
  			newrel->rd_partdesc_nodetached = NULL;
  			newrel->rd_partdesc_nodetached_xmin = InvalidTransactionId;
  			newrel->rd_pdcxt = NULL;
  			newrel->rd_pddcxt = NULL;
  		}
  
  #ifdef ADB
  		{
  			ListCell *lc;
  			bool keep_aux;
  
  			if (list_length(relation->rd_auxlist) != list_length(newrel->rd_auxlist))
  			{
  				keep_aux = false;
  			}else if (equal(relation->rd_auxlist, newrel->rd_auxlist))
  			{
  				keep_aux = true;
  			}else
  			{
  				keep_aux = true;
  				foreach(lc, newrel->rd_auxlist)
  				{
  					if (list_member_oid(relation->rd_auxlist, lfirst_oid(lc)) == false)
  					{
  						keep_aux = false;
  						break;
  					}
  				}
  			}
  			if (keep_aux)
  				SWAPFIELD(List *, rd_auxlist);
  
  			if (bms_equal(relation->rd_auxatt, newrel->rd_auxatt))
  				SWAPFIELD(Bitmapset *, rd_auxatt);
  		}
  		if (IsLocatorInfoEqual(relation->rd_locator_info, newrel->rd_locator_info))
  			SWAPFIELD(RelationLocInfo *, rd_locator_info);
  		if (IsExpansionCleanEqual(relation->rd_clean, newrel->rd_clean))
  			SWAPFIELD(struct ExpansionClean *, rd_clean);
  #endif /* ADB */
  
  #undef SWAPFIELD
  
  		/* And now we can throw away the temporary entry */
  		RelationDestroyRelation(newrel, !keep_tupdesc);
  	}
  }
  
  /*
   * RelationFlushRelation
   *
   *	 Rebuild the relation if it is open (refcount > 0), else blow it away.
   *	 This is used when we receive a cache invalidation event for the rel.
   */
  static void
  RelationFlushRelation(Relation relation)
  {
  	if (relation->rd_createSubid != InvalidSubTransactionId ||
  		relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId)
  	{
  		/*
  		 * New relcache entries are always rebuilt, not flushed; else we'd
  		 * forget the "new" status of the relation.  Ditto for the
  		 * new-relfilenode status.
  		 *
  		 * The rel could have zero refcnt here, so temporarily increment the
  		 * refcnt to ensure it's safe to rebuild it.  We can assume that the
  		 * current transaction has some lock on the rel already.
  		 */
  		RelationIncrementReferenceCount(relation);
  		RelationClearRelation(relation, true);
  		RelationDecrementReferenceCount(relation);
  	}
  	else
  	{
  		/*
  		 * Pre-existing rels can be dropped from the relcache if not open.
  		 */
  		bool		rebuild = !RelationHasReferenceCountZero(relation);
  
  		RelationClearRelation(relation, rebuild);
  	}
  }
  
  /*
   * RelationForgetRelation - caller reports that it dropped the relation
   */
  void
  RelationForgetRelation(Oid rid)
  {
  	Relation	relation;
  
  	RelationIdCacheLookup(rid, relation);
  
  	if (!PointerIsValid(relation))
  		return;					/* not in cache, nothing to do */
  
  	if (!RelationHasReferenceCountZero(relation))
  		elog(ERROR, "relation %u is still open", rid);
  
  	Assert(relation->rd_droppedSubid == InvalidSubTransactionId);
  	if (relation->rd_createSubid != InvalidSubTransactionId ||
  		relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId)
  	{
  		/*
  		 * In the event of subtransaction rollback, we must not forget
  		 * rd_*Subid.  Mark the entry "dropped" so RelationClearRelation()
  		 * invalidates it in lieu of destroying it.  (If we're in a top
  		 * transaction, we could opt to destroy the entry.)
  		 */
  		relation->rd_droppedSubid = GetCurrentSubTransactionId();
  	}
  
  	RelationClearRelation(relation, false);
  }
  
  /*
   *		RelationCacheInvalidateEntry
   *
   *		This routine is invoked for SI cache flush messages.
   *
   * Any relcache entry matching the relid must be flushed.  (Note: caller has
   * already determined that the relid belongs to our database or is a shared
   * relation.)
   *
   * We used to skip local relations, on the grounds that they could
   * not be targets of cross-backend SI update messages; but it seems
   * safer to process them, so that our *own* SI update messages will
   * have the same effects during CommandCounterIncrement for both
   * local and nonlocal relations.
   */
  void
  RelationCacheInvalidateEntry(Oid relationId)
  {
  	Relation	relation;
  
  	RelationIdCacheLookup(relationId, relation);
  
  	if (PointerIsValid(relation))
  	{
  		relcacheInvalsReceived++;
  		RelationFlushRelation(relation);
  	}
  }
  
  /*
   * RelationCacheInvalidate
   *	 Blow away cached relation descriptors that have zero reference counts,
   *	 and rebuild those with positive reference counts.  Also reset the smgr
   *	 relation cache and re-read relation mapping data.
   *
   *	 This is currently used only to recover from SI message buffer overflow,
   *	 so we do not touch relations having new-in-transaction relfilenodes; they
   *	 cannot be targets of cross-backend SI updates (and our own updates now go
   *	 through a separate linked list that isn't limited by the SI message
   *	 buffer size).
   *
   *	 We do this in two phases: the first pass deletes deletable items, and
   *	 the second one rebuilds the rebuildable items.  This is essential for
   *	 safety, because hash_seq_search only copes with concurrent deletion of
   *	 the element it is currently visiting.  If a second SI overflow were to
   *	 occur while we are walking the table, resulting in recursive entry to
   *	 this routine, we could crash because the inner invocation blows away
   *	 the entry next to be visited by the outer scan.  But this way is OK,
   *	 because (a) during the first pass we won't process any more SI messages,
   *	 so hash_seq_search will complete safely; (b) during the second pass we
   *	 only hold onto pointers to nondeletable entries.
   *
   *	 The two-phase approach also makes it easy to update relfilenodes for
   *	 mapped relations before we do anything else, and to ensure that the
   *	 second pass processes nailed-in-cache items before other nondeletable
   *	 items.  This should ensure that system catalogs are up to date before
   *	 we attempt to use them to reload information about other open relations.
   */
  void
  RelationCacheInvalidate(void)
  {
  	HASH_SEQ_STATUS status;
  	RelIdCacheEnt *idhentry;
  	Relation	relation;
  	List	   *rebuildFirstList = NIL;
  	List	   *rebuildList = NIL;
  	ListCell   *l;
  
  	/*
  	 * Reload relation mapping data before starting to reconstruct cache.
  	 */
  	RelationMapInvalidateAll();
  
  	/* Phase 1 */
  	hash_seq_init(&status, RelationIdCache);
  
  	while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
  	{
  		relation = idhentry->reldesc;
  
  		/* Must close all smgr references to avoid leaving dangling ptrs */
  		RelationCloseSmgr(relation);
  
  		/*
  		 * Ignore new relations; no other backend will manipulate them before
  		 * we commit.  Likewise, before replacing a relation's relfilenode, we
  		 * shall have acquired AccessExclusiveLock and drained any applicable
  		 * pending invalidations.
  		 */
  		if (relation->rd_createSubid != InvalidSubTransactionId ||
  			relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId)
  			continue;
  
  		relcacheInvalsReceived++;
  
  		if (RelationHasReferenceCountZero(relation))
  		{
  			/* Delete this entry immediately */
  			Assert(!relation->rd_isnailed);
  			RelationClearRelation(relation, false);
  		}
  		else
  		{
  			/*
  			 * If it's a mapped relation, immediately update its rd_node in
  			 * case its relfilenode changed.  We must do this during phase 1
  			 * in case the relation is consulted during rebuild of other
  			 * relcache entries in phase 2.  It's safe since consulting the
  			 * map doesn't involve any access to relcache entries.
  			 */
  			if (RelationIsMapped(relation))
  				RelationInitPhysicalAddr(relation);
  
  			/*
  			 * Add this entry to list of stuff to rebuild in second pass.
  			 * pg_class goes to the front of rebuildFirstList while
  			 * pg_class_oid_index goes to the back of rebuildFirstList, so
  			 * they are done first and second respectively.  Other nailed
  			 * relations go to the front of rebuildList, so they'll be done
  			 * next in no particular order; and everything else goes to the
  			 * back of rebuildList.
  			 */
  			if (RelationGetRelid(relation) == RelationRelationId)
  				rebuildFirstList = lcons(relation, rebuildFirstList);
  			else if (RelationGetRelid(relation) == ClassOidIndexId)
  				rebuildFirstList = lappend(rebuildFirstList, relation);
  			else if (relation->rd_isnailed)
  				rebuildList = lcons(relation, rebuildList);
  			else
  				rebuildList = lappend(rebuildList, relation);
  		}
  	}
  
  	/*
  	 * Now zap any remaining smgr cache entries.  This must happen before we
  	 * start to rebuild entries, since that may involve catalog fetches which
  	 * will re-open catalog files.
  	 */
  	smgrcloseall();
  
  	/* Phase 2: rebuild the items found to need rebuild in phase 1 */
  	foreach(l, rebuildFirstList)
  	{
  		relation = (Relation) lfirst(l);
  		RelationClearRelation(relation, true);
  	}
  	list_free(rebuildFirstList);
  	foreach(l, rebuildList)
  	{
  		relation = (Relation) lfirst(l);
  		RelationClearRelation(relation, true);
  	}
  	list_free(rebuildList);
  }
  
  /*
   * RelationCloseSmgrByOid - close a relcache entry's smgr link
   *
   * Needed in some cases where we are changing a relation's physical mapping.
   * The link will be automatically reopened on next use.
   */
  void
  RelationCloseSmgrByOid(Oid relationId)
  {
  	Relation	relation;
  
  	RelationIdCacheLookup(relationId, relation);
  
  	if (!PointerIsValid(relation))
  		return;					/* not in cache, nothing to do */
  
  	RelationCloseSmgr(relation);
  }
  
  static void
  RememberToFreeTupleDescAtEOX(TupleDesc td)
  {
  	if (EOXactTupleDescArray == NULL)
  	{
  		MemoryContext oldcxt;
  
  		oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  
  		EOXactTupleDescArray = (TupleDesc *) palloc(16 * sizeof(TupleDesc));
  		EOXactTupleDescArrayLen = 16;
  		NextEOXactTupleDescNum = 0;
  		MemoryContextSwitchTo(oldcxt);
  	}
  	else if (NextEOXactTupleDescNum >= EOXactTupleDescArrayLen)
  	{
  		int32		newlen = EOXactTupleDescArrayLen * 2;
  
  		Assert(EOXactTupleDescArrayLen > 0);
  
  		EOXactTupleDescArray = (TupleDesc *) repalloc(EOXactTupleDescArray,
  													  newlen * sizeof(TupleDesc));
  		EOXactTupleDescArrayLen = newlen;
  	}
  
  	EOXactTupleDescArray[NextEOXactTupleDescNum++] = td;
  }
  
  #ifdef USE_ASSERT_CHECKING
  static void
  AssertPendingSyncConsistency(Relation relation)
  {
  	bool		relcache_verdict =
  	RelationIsPermanent(relation) &&
  	((relation->rd_createSubid != InvalidSubTransactionId &&
  	  RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) ||
  	 relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId);
  
  	Assert(relcache_verdict == RelFileNodeSkippingWAL(relation->rd_node));
  
  	if (relation->rd_droppedSubid != InvalidSubTransactionId)
  		Assert(!relation->rd_isvalid &&
  			   (relation->rd_createSubid != InvalidSubTransactionId ||
  				relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId));
  }
  
  /*
   * AssertPendingSyncs_RelationCache
   *
   *	Assert that relcache.c and storage.c agree on whether to skip WAL.
   */
  void
  AssertPendingSyncs_RelationCache(void)
  {
  	HASH_SEQ_STATUS status;
  	LOCALLOCK  *locallock;
  	Relation   *rels;
  	int			maxrels;
  	int			nrels;
  	RelIdCacheEnt *idhentry;
  	int			i;
  
  	/*
  	 * Open every relation that this transaction has locked.  If, for some
  	 * relation, storage.c is skipping WAL and relcache.c is not skipping WAL,
  	 * a CommandCounterIncrement() typically yields a local invalidation
  	 * message that destroys the relcache entry.  By recreating such entries
  	 * here, we detect the problem.
  	 */
  	PushActiveSnapshot(GetTransactionSnapshot());
  	maxrels = 1;
  	rels = palloc(maxrels * sizeof(*rels));
  	nrels = 0;
  	hash_seq_init(&status, GetLockMethodLocalHash());
  	while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
  	{
  		Oid			relid;
  		Relation	r;
  
  		if (locallock->nLocks <= 0)
  			continue;
  		if ((LockTagType) locallock->tag.lock.locktag_type !=
  			LOCKTAG_RELATION)
  			continue;
  		relid = ObjectIdGetDatum(locallock->tag.lock.locktag_field2);
  		r = RelationIdGetRelation(relid);
  		if (!RelationIsValid(r))
  			continue;
  		if (nrels >= maxrels)
  		{
  			maxrels *= 2;
  			rels = repalloc(rels, maxrels * sizeof(*rels));
  		}
  		rels[nrels++] = r;
  	}
  
  	hash_seq_init(&status, RelationIdCache);
  	while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
  		AssertPendingSyncConsistency(idhentry->reldesc);
  
  	for (i = 0; i < nrels; i++)
  		RelationClose(rels[i]);
  	PopActiveSnapshot();
  }
  #endif
  
  /*
   * AtEOXact_RelationCache
   *
   *	Clean up the relcache at main-transaction commit or abort.
   *
   * Note: this must be called *before* processing invalidation messages.
   * In the case of abort, we don't want to try to rebuild any invalidated
   * cache entries (since we can't safely do database accesses).  Therefore
   * we must reset refcnts before handling pending invalidations.
   *
   * As of PostgreSQL 8.1, relcache refcnts should get released by the
   * ResourceOwner mechanism.  This routine just does a debugging
   * cross-check that no pins remain.  However, we also need to do special
   * cleanup when the current transaction created any relations or made use
   * of forced index lists.
   */
  void
  AtEOXact_RelationCache(bool isCommit)
  {
  	HASH_SEQ_STATUS status;
  	RelIdCacheEnt *idhentry;
  	int			i;
  
  	/*
  	 * Unless the eoxact_list[] overflowed, we only need to examine the rels
  	 * listed in it.  Otherwise fall back on a hash_seq_search scan.
  	 *
  	 * For simplicity, eoxact_list[] entries are not deleted till end of
  	 * top-level transaction, even though we could remove them at
  	 * subtransaction end in some cases, or remove relations from the list if
  	 * they are cleared for other reasons.  Therefore we should expect the
  	 * case that list entries are not found in the hashtable; if not, there's
  	 * nothing to do for them.
  	 */
  	if (eoxact_list_overflowed)
  	{
  		hash_seq_init(&status, RelationIdCache);
  		while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
  		{
  			AtEOXact_cleanup(idhentry->reldesc, isCommit);
  		}
  	}
  	else
  	{
  		for (i = 0; i < eoxact_list_len; i++)
  		{
  			idhentry = (RelIdCacheEnt *) hash_search(RelationIdCache,
  													 (void *) &eoxact_list[i],
  													 HASH_FIND,
  													 NULL);
  			if (idhentry != NULL)
  				AtEOXact_cleanup(idhentry->reldesc, isCommit);
  		}
  	}
  
  	if (EOXactTupleDescArrayLen > 0)
  	{
  		Assert(EOXactTupleDescArray != NULL);
  		for (i = 0; i < NextEOXactTupleDescNum; i++)
  			FreeTupleDesc(EOXactTupleDescArray[i]);
  		pfree(EOXactTupleDescArray);
  		EOXactTupleDescArray = NULL;
  	}
  
  	/* Now we're out of the transaction and can clear the lists */
  	eoxact_list_len = 0;
  	eoxact_list_overflowed = false;
  	NextEOXactTupleDescNum = 0;
  	EOXactTupleDescArrayLen = 0;
  }
  
  /*
   * AtEOXact_cleanup
   *
   *	Clean up a single rel at main-transaction commit or abort
   *
   * NB: this processing must be idempotent, because EOXactListAdd() doesn't
   * bother to prevent duplicate entries in eoxact_list[].
   */
  static void
  AtEOXact_cleanup(Relation relation, bool isCommit)
  {
  	bool		clear_relcache = false;
  
  	/*
  	 * The relcache entry's ref count should be back to its normal
  	 * not-in-a-transaction state: 0 unless it's nailed in cache.
  	 *
  	 * In bootstrap mode, this is NOT true, so don't check it --- the
  	 * bootstrap code expects relations to stay open across start/commit
  	 * transaction calls.  (That seems bogus, but it's not worth fixing.)
  	 *
  	 * Note: ideally this check would be applied to every relcache entry, not
  	 * just those that have eoxact work to do.  But it's not worth forcing a
  	 * scan of the whole relcache just for this.  (Moreover, doing so would
  	 * mean that assert-enabled testing never tests the hash_search code path
  	 * above, which seems a bad idea.)
  	 */
  #ifdef USE_ASSERT_CHECKING
  	if (!IsBootstrapProcessingMode())
  	{
  		int			expected_refcnt;
  
  		expected_refcnt = relation->rd_isnailed ? 1 : 0;
  		Assert(relation->rd_refcnt == expected_refcnt);
  	}
  #endif
  
  	/*
  	 * Is the relation live after this transaction ends?
  	 *
  	 * During commit, clear the relcache entry if it is preserved after
  	 * relation drop, in order not to orphan the entry.  During rollback,
  	 * clear the relcache entry if the relation is created in the current
  	 * transaction since it isn't interesting any longer once we are out of
  	 * the transaction.
  	 */
  	clear_relcache =
  		(isCommit ?
  		 relation->rd_droppedSubid != InvalidSubTransactionId :
  		 relation->rd_createSubid != InvalidSubTransactionId);
  
  	/*
  	 * Since we are now out of the transaction, reset the subids to zero. That
  	 * also lets RelationClearRelation() drop the relcache entry.
  	 */
  	relation->rd_createSubid = InvalidSubTransactionId;
  	relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  	relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  	relation->rd_droppedSubid = InvalidSubTransactionId;
  
  	if (clear_relcache)
  	{
  		if (RelationHasReferenceCountZero(relation))
  		{
  			RelationClearRelation(relation, false);
  			return;
  		}
  		else
  		{
  			/*
  			 * Hmm, somewhere there's a (leaked?) reference to the relation.
  			 * We daren't remove the entry for fear of dereferencing a
  			 * dangling pointer later.  Bleat, and mark it as not belonging to
  			 * the current transaction.  Hopefully it'll get cleaned up
  			 * eventually.  This must be just a WARNING to avoid
  			 * error-during-error-recovery loops.
  			 */
  			elog(WARNING, "cannot remove relcache entry for \"%s\" because it has nonzero refcount",
  				 RelationGetRelationName(relation));
  		}
  	}
  }
  
  /*
   * AtEOSubXact_RelationCache
   *
   *	Clean up the relcache at sub-transaction commit or abort.
   *
   * Note: this must be called *before* processing invalidation messages.
   */
  void
  AtEOSubXact_RelationCache(bool isCommit, SubTransactionId mySubid,
  						  SubTransactionId parentSubid)
  {
  	HASH_SEQ_STATUS status;
  	RelIdCacheEnt *idhentry;
  	int			i;
  
  	/*
  	 * Unless the eoxact_list[] overflowed, we only need to examine the rels
  	 * listed in it.  Otherwise fall back on a hash_seq_search scan.  Same
  	 * logic as in AtEOXact_RelationCache.
  	 */
  	if (eoxact_list_overflowed)
  	{
  		hash_seq_init(&status, RelationIdCache);
  		while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
  		{
  			AtEOSubXact_cleanup(idhentry->reldesc, isCommit,
  								mySubid, parentSubid);
  		}
  	}
  	else
  	{
  		for (i = 0; i < eoxact_list_len; i++)
  		{
  			idhentry = (RelIdCacheEnt *) hash_search(RelationIdCache,
  													 (void *) &eoxact_list[i],
  													 HASH_FIND,
  													 NULL);
  			if (idhentry != NULL)
  				AtEOSubXact_cleanup(idhentry->reldesc, isCommit,
  									mySubid, parentSubid);
  		}
  	}
  
  	/* Don't reset the list; we still need more cleanup later */
  }
  
  /*
   * AtEOSubXact_cleanup
   *
   *	Clean up a single rel at subtransaction commit or abort
   *
   * NB: this processing must be idempotent, because EOXactListAdd() doesn't
   * bother to prevent duplicate entries in eoxact_list[].
   */
  static void
  AtEOSubXact_cleanup(Relation relation, bool isCommit,
  					SubTransactionId mySubid, SubTransactionId parentSubid)
  {
  	/*
  	 * Is it a relation created in the current subtransaction?
  	 *
  	 * During subcommit, mark it as belonging to the parent, instead, as long
  	 * as it has not been dropped. Otherwise simply delete the relcache entry.
  	 * --- it isn't interesting any longer.
  	 */
  	if (relation->rd_createSubid == mySubid)
  	{
  		/*
  		 * Valid rd_droppedSubid means the corresponding relation is dropped
  		 * but the relcache entry is preserved for at-commit pending sync. We
  		 * need to drop it explicitly here not to make the entry orphan.
  		 */
  		Assert(relation->rd_droppedSubid == mySubid ||
  			   relation->rd_droppedSubid == InvalidSubTransactionId);
  		if (isCommit && relation->rd_droppedSubid == InvalidSubTransactionId)
  			relation->rd_createSubid = parentSubid;
  		else if (RelationHasReferenceCountZero(relation))
  		{
  			/* allow the entry to be removed */
  			relation->rd_createSubid = InvalidSubTransactionId;
  			relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  			relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  			relation->rd_droppedSubid = InvalidSubTransactionId;
  			RelationClearRelation(relation, false);
  			return;
  		}
  		else
  		{
  			/*
  			 * Hmm, somewhere there's a (leaked?) reference to the relation.
  			 * We daren't remove the entry for fear of dereferencing a
  			 * dangling pointer later.  Bleat, and transfer it to the parent
  			 * subtransaction so we can try again later.  This must be just a
  			 * WARNING to avoid error-during-error-recovery loops.
  			 */
  			relation->rd_createSubid = parentSubid;
  			elog(WARNING, "cannot remove relcache entry for \"%s\" because it has nonzero refcount",
  				 RelationGetRelationName(relation));
  		}
  	}
  
  	/*
  	 * Likewise, update or drop any new-relfilenode-in-subtransaction record
  	 * or drop record.
  	 */
  	if (relation->rd_newRelfilenodeSubid == mySubid)
  	{
  		if (isCommit)
  			relation->rd_newRelfilenodeSubid = parentSubid;
  		else
  			relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  	}
  
  	if (relation->rd_firstRelfilenodeSubid == mySubid)
  	{
  		if (isCommit)
  			relation->rd_firstRelfilenodeSubid = parentSubid;
  		else
  			relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  	}
  
  	if (relation->rd_droppedSubid == mySubid)
  	{
  		if (isCommit)
  			relation->rd_droppedSubid = parentSubid;
  		else
  			relation->rd_droppedSubid = InvalidSubTransactionId;
  	}
  }
  
  
  /*
   *		RelationBuildLocalRelation
   *			Build a relcache entry for an about-to-be-created relation,
   *			and enter it into the relcache.
   */
  Relation
  RelationBuildLocalRelation(const char *relname,
  						   Oid relnamespace,
  						   TupleDesc tupDesc,
  						   Oid relid,
  						   Oid accessmtd,
  						   Oid relfilenode,
  						   Oid reltablespace,
  						   bool shared_relation,
  						   bool mapped_relation,
  						   char relpersistence,
  						   char relkind)
  {
  	Relation	rel;
  	MemoryContext oldcxt;
  	int			natts = tupDesc->natts;
  	int			i;
  	bool		has_not_null;
  	bool		nailit;
  
  	AssertArg(natts >= 0);
  
  	/*
  	 * check for creation of a rel that must be nailed in cache.
  	 *
  	 * XXX this list had better match the relations specially handled in
  	 * RelationCacheInitializePhase2/3.
  	 */
  	switch (relid)
  	{
  		case DatabaseRelationId:
  		case AuthIdRelationId:
  		case AuthMemRelationId:
  		case RelationRelationId:
  		case AttributeRelationId:
  		case ProcedureRelationId:
  		case TypeRelationId:
  			nailit = true;
  			break;
  		default:
  			nailit = false;
  			break;
  	}
  
  	/*
  	 * check that hardwired list of shared rels matches what's in the
  	 * bootstrap .bki file.  If you get a failure here during initdb, you
  	 * probably need to fix IsSharedRelation() to match whatever you've done
  	 * to the set of shared relations.
  	 */
  	if (shared_relation != IsSharedRelation(relid))
  		elog(ERROR, "shared_relation flag for \"%s\" does not match IsSharedRelation(%u)",
  			 relname, relid);
  
  	/* Shared relations had better be mapped, too */
  	Assert(mapped_relation || !shared_relation);
  
  	/*
  	 * switch to the cache context to create the relcache entry.
  	 */
  	if (!CacheMemoryContext)
  		CreateCacheMemoryContext();
  
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  
  	/*
  	 * allocate a new relation descriptor and fill in basic state fields.
  	 */
  	rel = (Relation) palloc0(sizeof(RelationData));
  
  	/* make sure relation is marked as having no open file yet */
  	rel->rd_smgr = NULL;
  
  	/* mark it nailed if appropriate */
  	rel->rd_isnailed = nailit;
  
  	rel->rd_refcnt = nailit ? 1 : 0;
  
  	/* it's being created in this transaction */
  	rel->rd_createSubid = GetCurrentSubTransactionId();
  	rel->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  	rel->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  	rel->rd_droppedSubid = InvalidSubTransactionId;
  
  	/*
  	 * create a new tuple descriptor from the one passed in.  We do this
  	 * partly to copy it into the cache context, and partly because the new
  	 * relation can't have any defaults or constraints yet; they have to be
  	 * added in later steps, because they require additions to multiple system
  	 * catalogs.  We can copy attnotnull constraints here, however.
  	 */
  	rel->rd_att = CreateTupleDescCopy(tupDesc);
  	rel->rd_att->tdrefcount = 1;	/* mark as refcounted */
  	has_not_null = false;
  	for (i = 0; i < natts; i++)
  	{
  		Form_pg_attribute satt = TupleDescAttr(tupDesc, i);
  		Form_pg_attribute datt = TupleDescAttr(rel->rd_att, i);
  
  		datt->attidentity = satt->attidentity;
  		datt->attgenerated = satt->attgenerated;
  		datt->attnotnull = satt->attnotnull;
  		has_not_null |= satt->attnotnull;
  	}
  
  	if (has_not_null)
  	{
  		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
  
  		constr->has_not_null = true;
  		rel->rd_att->constr = constr;
  	}
  
  	/*
  	 * initialize relation tuple form (caller may add/override data later)
  	 */
  	rel->rd_rel = (Form_pg_class) palloc0(CLASS_TUPLE_SIZE);
  
  	namestrcpy(&rel->rd_rel->relname, relname);
  	rel->rd_rel->relnamespace = relnamespace;
  
  	rel->rd_rel->relkind = relkind;
  	rel->rd_rel->relnatts = natts;
  	rel->rd_rel->reltype = InvalidOid;
  	/* needed when bootstrapping: */
  	rel->rd_rel->relowner = BOOTSTRAP_SUPERUSERID;
  
  	/* set up persistence and relcache fields dependent on it */
  	rel->rd_rel->relpersistence = relpersistence;
  	switch (relpersistence)
  	{
  		case RELPERSISTENCE_UNLOGGED:
  		case RELPERSISTENCE_PERMANENT:
  			rel->rd_backend = InvalidBackendId;
  			rel->rd_islocaltemp = false;
  			break;
  		case RELPERSISTENCE_TEMP:
  			Assert(isTempOrTempToastNamespace(relnamespace));
  			rel->rd_backend = BackendIdForTempRelations();
  			rel->rd_islocaltemp = true;
  			break;
  		default:
  			elog(ERROR, "invalid relpersistence: %c", relpersistence);
  			break;
  	}
  
  	/* if it's a materialized view, it's not populated initially */
  	if (relkind == RELKIND_MATVIEW)
  		rel->rd_rel->relispopulated = false;
  	else
  		rel->rd_rel->relispopulated = true;
  
  	/* set replica identity -- system catalogs and non-tables don't have one */
  	if (!IsCatalogNamespace(relnamespace) &&
  		(relkind == RELKIND_RELATION ||
  		 relkind == RELKIND_MATVIEW ||
  		 relkind == RELKIND_PARTITIONED_TABLE))
  		rel->rd_rel->relreplident = REPLICA_IDENTITY_DEFAULT;
  	else
  		rel->rd_rel->relreplident = REPLICA_IDENTITY_NOTHING;
  
  	/*
  	 * Insert relation physical and logical identifiers (OIDs) into the right
  	 * places.  For a mapped relation, we set relfilenode to zero and rely on
  	 * RelationInitPhysicalAddr to consult the map.
  	 */
  	rel->rd_rel->relisshared = shared_relation;
  
  	RelationGetRelid(rel) = relid;
  
  	for (i = 0; i < natts; i++)
  		TupleDescAttr(rel->rd_att, i)->attrelid = relid;
  
  	rel->rd_rel->reltablespace = reltablespace;
  
  	if (mapped_relation)
  	{
  		rel->rd_rel->relfilenode = InvalidOid;
  		/* Add it to the active mapping information */
  		RelationMapUpdateMap(relid, relfilenode, shared_relation, true);
  	}
  	else
  		rel->rd_rel->relfilenode = relfilenode;
  
  	RelationInitLockInfo(rel);	/* see lmgr.c */
  
  	RelationInitPhysicalAddr(rel);
  
  	rel->rd_rel->relam = accessmtd;
  
  	/*
  	 * RelationInitTableAccessMethod will do syscache lookups, so we mustn't
  	 * run it in CacheMemoryContext.  Fortunately, the remaining steps don't
  	 * require a long-lived current context.
  	 */
  	MemoryContextSwitchTo(oldcxt);
  
  	if (relkind == RELKIND_RELATION ||
  		relkind == RELKIND_SEQUENCE ||
  		relkind == RELKIND_TOASTVALUE ||
  		relkind == RELKIND_MATVIEW)
  		RelationInitTableAccessMethod(rel);
  
  	/*
  	 * Okay to insert into the relcache hash table.
  	 *
  	 * Ordinarily, there should certainly not be an existing hash entry for
  	 * the same OID; but during bootstrap, when we create a "real" relcache
  	 * entry for one of the bootstrap relations, we'll be overwriting the
  	 * phony one created with formrdesc.  So allow that to happen for nailed
  	 * rels.
  	 */
  	RelationCacheInsert(rel, nailit);
  
  	/*
  	 * Flag relation as needing eoxact cleanup (to clear rd_createSubid). We
  	 * can't do this before storing relid in it.
  	 */
  	EOXactListAdd(rel);
  
  	/* It's fully valid */
  	rel->rd_isvalid = true;
  
  	/*
  	 * Caller expects us to pin the returned entry.
  	 */
  	RelationIncrementReferenceCount(rel);
  
  	return rel;
  }
  
  
  /*
   * RelationSetNewRelfilenode
   *
   * Assign a new relfilenode (physical file name), and possibly a new
   * persistence setting, to the relation.
   *
   * This allows a full rewrite of the relation to be done with transactional
   * safety (since the filenode assignment can be rolled back).  Note however
   * that there is no simple way to access the relation's old data for the
   * remainder of the current transaction.  This limits the usefulness to cases
   * such as TRUNCATE or rebuilding an index from scratch.
   *
   * Caller must already hold exclusive lock on the relation.
   */
  void
  RelationSetNewRelfilenode(Relation relation, char persistence)
  {
  	Oid			newrelfilenode;
  	Relation	pg_class;
  	HeapTuple	tuple;
  	Form_pg_class classform;
  	MultiXactId minmulti = InvalidMultiXactId;
  	TransactionId freezeXid = InvalidTransactionId;
  	RelFileNode newrnode;
  
  	/* Allocate a new relfilenode */
  	newrelfilenode = GetNewRelFileNode(relation->rd_rel->reltablespace, NULL,
  									   persistence);
  
  	/*
  	 * Get a writable copy of the pg_class tuple for the given relation.
  	 */
  	pg_class = table_open(RelationRelationId, RowExclusiveLock);
  
  	tuple = SearchSysCacheCopy1(RELOID,
  								ObjectIdGetDatum(RelationGetRelid(relation)));
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "could not find tuple for relation %u",
  			 RelationGetRelid(relation));
  	classform = (Form_pg_class) GETSTRUCT(tuple);
  
  	/*
  	 * Schedule unlinking of the old storage at transaction commit.
  	 */
  	RelationDropStorage(relation);
  
  	/*
  	 * Create storage for the main fork of the new relfilenode.  If it's a
  	 * table-like object, call into the table AM to do so, which'll also
  	 * create the table's init fork if needed.
  	 *
  	 * NOTE: If relevant for the AM, any conflict in relfilenode value will be
  	 * caught here, if GetNewRelFileNode messes up for any reason.
  	 */
  	newrnode = relation->rd_node;
  	newrnode.relNode = newrelfilenode;
  
  	switch (relation->rd_rel->relkind)
  	{
  		case RELKIND_INDEX:
  		case RELKIND_SEQUENCE:
  			{
  				/* handle these directly, at least for now */
  				SMgrRelation srel;
  
  				srel = RelationCreateStorage(newrnode, persistence);
  				smgrclose(srel);
  			}
  			break;
  
  		case RELKIND_RELATION:
  		case RELKIND_TOASTVALUE:
  		case RELKIND_MATVIEW:
  			table_relation_set_new_filenode(relation, &newrnode,
  											persistence,
  											&freezeXid, &minmulti);
  			break;
  
  		default:
  			/* we shouldn't be called for anything else */
  			elog(ERROR, "relation \"%s\" does not have storage",
  				 RelationGetRelationName(relation));
  			break;
  	}
  
  	/*
  	 * If we're dealing with a mapped index, pg_class.relfilenode doesn't
  	 * change; instead we have to send the update to the relation mapper.
  	 *
  	 * For mapped indexes, we don't actually change the pg_class entry at all;
  	 * this is essential when reindexing pg_class itself.  That leaves us with
  	 * possibly-inaccurate values of relpages etc, but those will be fixed up
  	 * later.
  	 */
  	if (RelationIsMapped(relation))
  	{
  		/* This case is only supported for indexes */
  		Assert(relation->rd_rel->relkind == RELKIND_INDEX);
  
  		/* Since we're not updating pg_class, these had better not change */
  		Assert(classform->relfrozenxid == freezeXid);
  		Assert(classform->relminmxid == minmulti);
  		Assert(classform->relpersistence == persistence);
  
  		/*
  		 * In some code paths it's possible that the tuple update we'd
  		 * otherwise do here is the only thing that would assign an XID for
  		 * the current transaction.  However, we must have an XID to delete
  		 * files, so make sure one is assigned.
  		 */
  		(void) GetCurrentTransactionId();
  
  		/* Do the deed */
  		RelationMapUpdateMap(RelationGetRelid(relation),
  							 newrelfilenode,
  							 relation->rd_rel->relisshared,
  							 false);
  
  		/* Since we're not updating pg_class, must trigger inval manually */
  		CacheInvalidateRelcache(relation);
  	}
  	else
  	{
  		/* Normal case, update the pg_class entry */
  		classform->relfilenode = newrelfilenode;
  
  		/* relpages etc. never change for sequences */
  		if (relation->rd_rel->relkind != RELKIND_SEQUENCE)
  		{
  			classform->relpages = 0;	/* it's empty until further notice */
  			classform->reltuples = -1;
  			classform->relallvisible = 0;
  		}
  		classform->relfrozenxid = freezeXid;
  		classform->relminmxid = minmulti;
  		classform->relpersistence = persistence;
  
  		CatalogTupleUpdate(pg_class, &tuple->t_self, tuple);
  	}
  
  	heap_freetuple(tuple);
  
  	table_close(pg_class, RowExclusiveLock);
  
  	/*
  	 * Make the pg_class row change or relation map change visible.  This will
  	 * cause the relcache entry to get updated, too.
  	 */
  	CommandCounterIncrement();
  
  	RelationAssumeNewRelfilenode(relation);
  }
  
  /*
   * RelationAssumeNewRelfilenode
   *
   * Code that modifies pg_class.reltablespace or pg_class.relfilenode must call
   * this.  The call shall precede any code that might insert WAL records whose
   * replay would modify bytes in the new RelFileNode, and the call shall follow
   * any WAL modifying bytes in the prior RelFileNode.  See struct RelationData.
   * Ideally, call this as near as possible to the CommandCounterIncrement()
   * that makes the pg_class change visible (before it or after it); that
   * minimizes the chance of future development adding a forbidden WAL insertion
   * between RelationAssumeNewRelfilenode() and CommandCounterIncrement().
   */
  void
  RelationAssumeNewRelfilenode(Relation relation)
  {
  	relation->rd_newRelfilenodeSubid = GetCurrentSubTransactionId();
  	if (relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)
  		relation->rd_firstRelfilenodeSubid = relation->rd_newRelfilenodeSubid;
  
  	/* Flag relation as needing eoxact cleanup (to clear these fields) */
  	EOXactListAdd(relation);
  }
  
  
  /*
   *		RelationCacheInitialize
   *
   *		This initializes the relation descriptor cache.  At the time
   *		that this is invoked, we can't do database access yet (mainly
   *		because the transaction subsystem is not up); all we are doing
   *		is making an empty cache hashtable.  This must be done before
   *		starting the initialization transaction, because otherwise
   *		AtEOXact_RelationCache would crash if that transaction aborts
   *		before we can get the relcache set up.
   */
  
  #define INITRELCACHESIZE		400
  
  void
  RelationCacheInitialize(void)
  {
  	HASHCTL		ctl;
  
  	/*
  	 * make sure cache memory context exists
  	 */
  	if (!CacheMemoryContext)
  		CreateCacheMemoryContext();
  
  	/*
  	 * create hashtable that indexes the relcache
  	 */
  	ctl.keysize = sizeof(Oid);
  	ctl.entrysize = sizeof(RelIdCacheEnt);
  	RelationIdCache = hash_create("Relcache by OID", INITRELCACHESIZE,
  								  &ctl, HASH_ELEM | HASH_BLOBS);
  
  	/*
  	 * relation mapper needs to be initialized too
  	 */
  	RelationMapInitialize();
  }
  
  /*
   *		RelationCacheInitializePhase2
   *
   *		This is called to prepare for access to shared catalogs during startup.
   *		We must at least set up nailed reldescs for pg_database, pg_authid,
   *		pg_auth_members, and pg_shseclabel. Ideally we'd like to have reldescs
   *		for their indexes, too.  We attempt to load this information from the
   *		shared relcache init file.  If that's missing or broken, just make
   *		phony entries for the catalogs themselves.
   *		RelationCacheInitializePhase3 will clean up as needed.
   */
  void
  RelationCacheInitializePhase2(void)
  {
  	MemoryContext oldcxt;
  
  	/*
  	 * relation mapper needs initialized too
  	 */
  	RelationMapInitializePhase2();
  
  	/*
  	 * In bootstrap mode, the shared catalogs aren't there yet anyway, so do
  	 * nothing.
  	 */
  	if (IsBootstrapProcessingMode())
  		return;
  
  	/*
  	 * switch to cache memory context
  	 */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  
  	/*
  	 * Try to load the shared relcache cache file.  If unsuccessful, bootstrap
  	 * the cache with pre-made descriptors for the critical shared catalogs.
  	 */
  	if (!load_relcache_init_file(true))
  	{
  		formrdesc("pg_database", DatabaseRelation_Rowtype_Id, true,
  				  Natts_pg_database, Desc_pg_database);
  		formrdesc("pg_authid", AuthIdRelation_Rowtype_Id, true,
  				  Natts_pg_authid, Desc_pg_authid);
  		formrdesc("pg_auth_members", AuthMemRelation_Rowtype_Id, true,
  				  Natts_pg_auth_members, Desc_pg_auth_members);
  		formrdesc("pg_shseclabel", SharedSecLabelRelation_Rowtype_Id, true,
  				  Natts_pg_shseclabel, Desc_pg_shseclabel);
  		formrdesc("pg_subscription", SubscriptionRelation_Rowtype_Id, true,
  				  Natts_pg_subscription, Desc_pg_subscription);
  
  #ifdef ADB
  		formrdesc("pgxc_node", PgxcNodeRelation_Rowtype_Id, true,
  				  Natts_pgxc_node, Desc_pgxc_node);
  #define NUM_CRITICAL_SHARED_RELS	6
  #else /* ADB */
  #define NUM_CRITICAL_SHARED_RELS	5	/* fix if you change list above */
  #endif /* ADB */
  	}
  
  	MemoryContextSwitchTo(oldcxt);
  }
  
  /*
   *		RelationCacheInitializePhase3
   *
   *		This is called as soon as the catcache and transaction system
   *		are functional and we have determined MyDatabaseId.  At this point
   *		we can actually read data from the database's system catalogs.
   *		We first try to read pre-computed relcache entries from the local
   *		relcache init file.  If that's missing or broken, make phony entries
   *		for the minimum set of nailed-in-cache relations.  Then (unless
   *		bootstrapping) make sure we have entries for the critical system
   *		indexes.  Once we've done all this, we have enough infrastructure to
   *		open any system catalog or use any catcache.  The last step is to
   *		rewrite the cache files if needed.
   */
  void
  RelationCacheInitializePhase3(void)
  {
  	HASH_SEQ_STATUS status;
  	RelIdCacheEnt *idhentry;
  	MemoryContext oldcxt;
  	bool		needNewCacheFile = !criticalSharedRelcachesBuilt;
  
  	/*
  	 * relation mapper needs initialized too
  	 */
  	RelationMapInitializePhase3();
  
  	/*
  	 * switch to cache memory context
  	 */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  
  	/*
  	 * Try to load the local relcache cache file.  If unsuccessful, bootstrap
  	 * the cache with pre-made descriptors for the critical "nailed-in" system
  	 * catalogs.
  	 */
  	if (IsBootstrapProcessingMode() ||
  		!load_relcache_init_file(false))
  	{
  		needNewCacheFile = true;
  
  		formrdesc("pg_class", RelationRelation_Rowtype_Id, false,
  				  Natts_pg_class, Desc_pg_class);
  		formrdesc("pg_attribute", AttributeRelation_Rowtype_Id, false,
  				  Natts_pg_attribute, Desc_pg_attribute);
  		formrdesc("pg_proc", ProcedureRelation_Rowtype_Id, false,
  				  Natts_pg_proc, Desc_pg_proc);
  		formrdesc("pg_type", TypeRelation_Rowtype_Id, false,
  				  Natts_pg_type, Desc_pg_type);
  
  #define NUM_CRITICAL_LOCAL_RELS 4	/* fix if you change list above */
  	}
  
  	MemoryContextSwitchTo(oldcxt);
  
  	/* In bootstrap mode, the faked-up formrdesc info is all we'll have */
  	if (IsBootstrapProcessingMode())
  		return;
  
  	/*
  	 * If we didn't get the critical system indexes loaded into relcache, do
  	 * so now.  These are critical because the catcache and/or opclass cache
  	 * depend on them for fetches done during relcache load.  Thus, we have an
  	 * infinite-recursion problem.  We can break the recursion by doing
  	 * heapscans instead of indexscans at certain key spots. To avoid hobbling
  	 * performance, we only want to do that until we have the critical indexes
  	 * loaded into relcache.  Thus, the flag criticalRelcachesBuilt is used to
  	 * decide whether to do heapscan or indexscan at the key spots, and we set
  	 * it true after we've loaded the critical indexes.
  	 *
  	 * The critical indexes are marked as "nailed in cache", partly to make it
  	 * easy for load_relcache_init_file to count them, but mainly because we
  	 * cannot flush and rebuild them once we've set criticalRelcachesBuilt to
  	 * true.  (NOTE: perhaps it would be possible to reload them by
  	 * temporarily setting criticalRelcachesBuilt to false again.  For now,
  	 * though, we just nail 'em in.)
  	 *
  	 * RewriteRelRulenameIndexId and TriggerRelidNameIndexId are not critical
  	 * in the same way as the others, because the critical catalogs don't
  	 * (currently) have any rules or triggers, and so these indexes can be
  	 * rebuilt without inducing recursion.  However they are used during
  	 * relcache load when a rel does have rules or triggers, so we choose to
  	 * nail them for performance reasons.
  	 */
  	if (!criticalRelcachesBuilt)
  	{
  		load_critical_index(ClassOidIndexId,
  							RelationRelationId);
  		load_critical_index(AttributeRelidNumIndexId,
  							AttributeRelationId);
  		load_critical_index(IndexRelidIndexId,
  							IndexRelationId);
  		load_critical_index(OpclassOidIndexId,
  							OperatorClassRelationId);
  		load_critical_index(AccessMethodProcedureIndexId,
  							AccessMethodProcedureRelationId);
  		load_critical_index(RewriteRelRulenameIndexId,
  							RewriteRelationId);
  		load_critical_index(TriggerRelidNameIndexId,
  							TriggerRelationId);
  
  #define NUM_CRITICAL_LOCAL_INDEXES	7	/* fix if you change list above */
  
  		criticalRelcachesBuilt = true;
  	}
  
  	/*
  	 * Process critical shared indexes too.
  	 *
  	 * DatabaseNameIndexId isn't critical for relcache loading, but rather for
  	 * initial lookup of MyDatabaseId, without which we'll never find any
  	 * non-shared catalogs at all.  Autovacuum calls InitPostgres with a
  	 * database OID, so it instead depends on DatabaseOidIndexId.  We also
  	 * need to nail up some indexes on pg_authid and pg_auth_members for use
  	 * during client authentication.  SharedSecLabelObjectIndexId isn't
  	 * critical for the core system, but authentication hooks might be
  	 * interested in it.
  	 */
  	if (!criticalSharedRelcachesBuilt)
  	{
  		load_critical_index(DatabaseNameIndexId,
  							DatabaseRelationId);
  		load_critical_index(DatabaseOidIndexId,
  							DatabaseRelationId);
  		load_critical_index(AuthIdRolnameIndexId,
  							AuthIdRelationId);
  		load_critical_index(AuthIdOidIndexId,
  							AuthIdRelationId);
  		load_critical_index(AuthMemMemRoleIndexId,
  							AuthMemRelationId);
  		load_critical_index(SharedSecLabelObjectIndexId,
  							SharedSecLabelRelationId);
  
  #ifdef ADB
  		load_critical_index(PgxcNodeOidIndexId,
  							PgxcNodeRelationId);
  #define NUM_CRITICAL_SHARED_INDEXES 7
  #else
  #define NUM_CRITICAL_SHARED_INDEXES 6	/* fix if you change list above */
  #endif
  
  		criticalSharedRelcachesBuilt = true;
  	}
  
  	/*
  	 * Now, scan all the relcache entries and update anything that might be
  	 * wrong in the results from formrdesc or the relcache cache file. If we
  	 * faked up relcache entries using formrdesc, then read the real pg_class
  	 * rows and replace the fake entries with them. Also, if any of the
  	 * relcache entries have rules, triggers, or security policies, load that
  	 * info the hard way since it isn't recorded in the cache file.
  	 *
  	 * Whenever we access the catalogs to read data, there is a possibility of
  	 * a shared-inval cache flush causing relcache entries to be removed.
  	 * Since hash_seq_search only guarantees to still work after the *current*
  	 * entry is removed, it's unsafe to continue the hashtable scan afterward.
  	 * We handle this by restarting the scan from scratch after each access.
  	 * This is theoretically O(N^2), but the number of entries that actually
  	 * need to be fixed is small enough that it doesn't matter.
  	 */
  	hash_seq_init(&status, RelationIdCache);
  
  	while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
  	{
  		Relation	relation = idhentry->reldesc;
  		bool		restart = false;
  
  		/*
  		 * Make sure *this* entry doesn't get flushed while we work with it.
  		 */
  		RelationIncrementReferenceCount(relation);
  
  		/*
  		 * If it's a faked-up entry, read the real pg_class tuple.
  		 */
  		if (relation->rd_rel->relowner == InvalidOid)
  		{
  			HeapTuple	htup;
  			Form_pg_class relp;
  
  			htup = SearchSysCache1(RELOID,
  								   ObjectIdGetDatum(RelationGetRelid(relation)));
  			if (!HeapTupleIsValid(htup))
  				elog(FATAL, "cache lookup failed for relation %u",
  					 RelationGetRelid(relation));
  			relp = (Form_pg_class) GETSTRUCT(htup);
  
  			/*
  			 * Copy tuple to relation->rd_rel. (See notes in
  			 * AllocateRelationDesc())
  			 */
  			memcpy((char *) relation->rd_rel, (char *) relp, CLASS_TUPLE_SIZE);
  
  			/* Update rd_options while we have the tuple */
  			if (relation->rd_options)
  				pfree(relation->rd_options);
  			RelationParseRelOptions(relation, htup);
  
  			/*
  			 * Check the values in rd_att were set up correctly.  (We cannot
  			 * just copy them over now: formrdesc must have set up the rd_att
  			 * data correctly to start with, because it may already have been
  			 * copied into one or more catcache entries.)
  			 */
  			Assert(relation->rd_att->tdtypeid == relp->reltype);
  			Assert(relation->rd_att->tdtypmod == -1);
  
  			ReleaseSysCache(htup);
  
  			/* relowner had better be OK now, else we'll loop forever */
  			if (relation->rd_rel->relowner == InvalidOid)
  				elog(ERROR, "invalid relowner in pg_class entry for \"%s\"",
  					 RelationGetRelationName(relation));
  
  			restart = true;
  		}
  
  		/*
  		 * Fix data that isn't saved in relcache cache file.
  		 *
  		 * relhasrules or relhastriggers could possibly be wrong or out of
  		 * date.  If we don't actually find any rules or triggers, clear the
  		 * local copy of the flag so that we don't get into an infinite loop
  		 * here.  We don't make any attempt to fix the pg_class entry, though.
  		 */
  		if (relation->rd_rel->relhasrules && relation->rd_rules == NULL)
  		{
  			RelationBuildRuleLock(relation);
  			if (relation->rd_rules == NULL)
  				relation->rd_rel->relhasrules = false;
  			restart = true;
  		}
  		if (relation->rd_rel->relhastriggers && relation->trigdesc == NULL)
  		{
  			RelationBuildTriggers(relation);
  			if (relation->trigdesc == NULL)
  				relation->rd_rel->relhastriggers = false;
  			restart = true;
  		}
  
  		/*
  		 * Re-load the row security policies if the relation has them, since
  		 * they are not preserved in the cache.  Note that we can never NOT
  		 * have a policy while relrowsecurity is true,
  		 * RelationBuildRowSecurity will create a single default-deny policy
  		 * if there is no policy defined in pg_policy.
  		 */
  		if (relation->rd_rel->relrowsecurity && relation->rd_rsdesc == NULL)
  		{
  			RelationBuildRowSecurity(relation);
  
  			Assert(relation->rd_rsdesc != NULL);
  			restart = true;
  		}
  
  		/* Reload tableam data if needed */
  		if (relation->rd_tableam == NULL &&
  			(relation->rd_rel->relkind == RELKIND_RELATION ||
  			 relation->rd_rel->relkind == RELKIND_SEQUENCE ||
  			 relation->rd_rel->relkind == RELKIND_TOASTVALUE ||
  			 relation->rd_rel->relkind == RELKIND_MATVIEW))
  		{
  			RelationInitTableAccessMethod(relation);
  			Assert(relation->rd_tableam != NULL);
  
  			restart = true;
  		}
  
  		/* Release hold on the relation */
  		RelationDecrementReferenceCount(relation);
  
  		/* Now, restart the hashtable scan if needed */
  		if (restart)
  		{
  			hash_seq_term(&status);
  			hash_seq_init(&status, RelationIdCache);
  		}
  	}
  
  	/*
  	 * Lastly, write out new relcache cache files if needed.  We don't bother
  	 * to distinguish cases where only one of the two needs an update.
  	 */
  	if (needNewCacheFile)
  	{
  		/*
  		 * Force all the catcaches to finish initializing and thereby open the
  		 * catalogs and indexes they use.  This will preload the relcache with
  		 * entries for all the most important system catalogs and indexes, so
  		 * that the init files will be most useful for future backends.
  		 */
  		InitCatalogCachePhase2();
  
  		/* now write the files */
  		write_relcache_init_file(true);
  		write_relcache_init_file(false);
  	}
  }
  
  /*
   * Load one critical system index into the relcache
   *
   * indexoid is the OID of the target index, heapoid is the OID of the catalog
   * it belongs to.
   */
  static void
  load_critical_index(Oid indexoid, Oid heapoid)
  {
  	Relation	ird;
  
  	/*
  	 * We must lock the underlying catalog before locking the index to avoid
  	 * deadlock, since RelationBuildDesc might well need to read the catalog,
  	 * and if anyone else is exclusive-locking this catalog and index they'll
  	 * be doing it in that order.
  	 */
  	LockRelationOid(heapoid, AccessShareLock);
  	LockRelationOid(indexoid, AccessShareLock);
  	ird = RelationBuildDesc(indexoid, true);
  	if (ird == NULL)
  		elog(PANIC, "could not open critical system index %u", indexoid);
  	ird->rd_isnailed = true;
  	ird->rd_refcnt = 1;
  	UnlockRelationOid(indexoid, AccessShareLock);
  	UnlockRelationOid(heapoid, AccessShareLock);
  
  	(void) RelationGetIndexAttOptions(ird, false);
  }
  
  /*
   * GetPgClassDescriptor -- get a predefined tuple descriptor for pg_class
   * GetPgIndexDescriptor -- get a predefined tuple descriptor for pg_index
   *
   * We need this kluge because we have to be able to access non-fixed-width
   * fields of pg_class and pg_index before we have the standard catalog caches
   * available.  We use predefined data that's set up in just the same way as
   * the bootstrapped reldescs used by formrdesc().  The resulting tupdesc is
   * not 100% kosher: it does not have the correct rowtype OID in tdtypeid, nor
   * does it have a TupleConstr field.  But it's good enough for the purpose of
   * extracting fields.
   */
  static TupleDesc
  BuildHardcodedDescriptor(int natts, const FormData_pg_attribute *attrs)
  {
  	TupleDesc	result;
  	MemoryContext oldcxt;
  	int			i;
  
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  
  	result = CreateTemplateTupleDesc(natts);
  	result->tdtypeid = RECORDOID;	/* not right, but we don't care */
  	result->tdtypmod = -1;
  
  	for (i = 0; i < natts; i++)
  	{
  		memcpy(TupleDescAttr(result, i), &attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
  		/* make sure attcacheoff is valid */
  		TupleDescAttr(result, i)->attcacheoff = -1;
  	}
  
  	/* initialize first attribute's attcacheoff, cf RelationBuildTupleDesc */
  	TupleDescAttr(result, 0)->attcacheoff = 0;
  
  	/* Note: we don't bother to set up a TupleConstr entry */
  
  	MemoryContextSwitchTo(oldcxt);
  
  	return result;
  }
  
  static TupleDesc
  GetPgClassDescriptor(void)
  {
  	static TupleDesc pgclassdesc = NULL;
  
  	/* Already done? */
  	if (pgclassdesc == NULL)
  		pgclassdesc = BuildHardcodedDescriptor(Natts_pg_class,
  											   Desc_pg_class);
  
  	return pgclassdesc;
  }
  
  static TupleDesc
  GetPgIndexDescriptor(void)
  {
  	static TupleDesc pgindexdesc = NULL;
  
  	/* Already done? */
  	if (pgindexdesc == NULL)
  		pgindexdesc = BuildHardcodedDescriptor(Natts_pg_index,
  											   Desc_pg_index);
  
  	return pgindexdesc;
  }
  
  /*
   * Load any default attribute value definitions for the relation.
   *
   * ndef is the number of attributes that were marked atthasdef.
   *
   * Note: we don't make it a hard error to be missing some pg_attrdef records.
   * We can limp along as long as nothing needs to use the default value.  Code
   * that fails to find an expected AttrDefault record should throw an error.
   */
  static void
  AttrDefaultFetch(Relation relation, int ndef)
  {
  	AttrDefault *attrdef;
  	Relation	adrel;
  	SysScanDesc adscan;
  	ScanKeyData skey;
  	HeapTuple	htup;
  	int			found = 0;
  
  	/* Allocate array with room for as many entries as expected */
  	attrdef = (AttrDefault *)
  		MemoryContextAllocZero(CacheMemoryContext,
  							   ndef * sizeof(AttrDefault));
  
  	/* Search pg_attrdef for relevant entries */
  	ScanKeyInit(&skey,
  				Anum_pg_attrdef_adrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	adrel = table_open(AttrDefaultRelationId, AccessShareLock);
  	adscan = systable_beginscan(adrel, AttrDefaultIndexId, true,
  								NULL, 1, &skey);
  
  	while (HeapTupleIsValid(htup = systable_getnext(adscan)))
  	{
  		Form_pg_attrdef adform = (Form_pg_attrdef) GETSTRUCT(htup);
  		Datum		val;
  		bool		isnull;
  
  		/* protect limited size of array */
  		if (found >= ndef)
  		{
  			elog(WARNING, "unexpected pg_attrdef record found for attribute %d of relation \"%s\"",
  				 adform->adnum, RelationGetRelationName(relation));
  			break;
  		}
  
  		val = fastgetattr(htup,
  						  Anum_pg_attrdef_adbin,
  						  adrel->rd_att, &isnull);
  		if (isnull)
  			elog(WARNING, "null adbin for attribute %d of relation \"%s\"",
  				 adform->adnum, RelationGetRelationName(relation));
  		else
  		{
  			/* detoast and convert to cstring in caller's context */
  			char	   *s = TextDatumGetCString(val);
  
  			attrdef[found].adnum = adform->adnum;
  			attrdef[found].adbin = MemoryContextStrdup(CacheMemoryContext, s);
  			pfree(s);
  			found++;
  		}
  	}
  
  	systable_endscan(adscan);
  	table_close(adrel, AccessShareLock);
  
  	if (found != ndef)
  		elog(WARNING, "%d pg_attrdef record(s) missing for relation \"%s\"",
  			 ndef - found, RelationGetRelationName(relation));
  
  	/*
  	 * Sort the AttrDefault entries by adnum, for the convenience of
  	 * equalTupleDescs().  (Usually, they already will be in order, but this
  	 * might not be so if systable_getnext isn't using an index.)
  	 */
  	if (found > 1)
  		qsort(attrdef, found, sizeof(AttrDefault), AttrDefaultCmp);
  
  	/* Install array only after it's fully valid */
  	relation->rd_att->constr->defval = attrdef;
  	relation->rd_att->constr->num_defval = found;
  }
  
  /*
   * qsort comparator to sort AttrDefault entries by adnum
   */
  static int
  AttrDefaultCmp(const void *a, const void *b)
  {
  	const AttrDefault *ada = (const AttrDefault *) a;
  	const AttrDefault *adb = (const AttrDefault *) b;
  
  	return ada->adnum - adb->adnum;
  }
  
  /*
   * Load any check constraints for the relation.
   *
   * As with defaults, if we don't find the expected number of them, just warn
   * here.  The executor should throw an error if an INSERT/UPDATE is attempted.
   */
  static void
  CheckConstraintFetch(Relation relation)
  {
  	ConstrCheck *check;
  	int			ncheck = relation->rd_rel->relchecks;
  	Relation	conrel;
  	SysScanDesc conscan;
  	ScanKeyData skey[1];
  	HeapTuple	htup;
  	int			found = 0;
  
  	/* Allocate array with room for as many entries as expected */
  	check = (ConstrCheck *)
  		MemoryContextAllocZero(CacheMemoryContext,
  							   ncheck * sizeof(ConstrCheck));
  
  	/* Search pg_constraint for relevant entries */
  	ScanKeyInit(&skey[0],
  				Anum_pg_constraint_conrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	conrel = table_open(ConstraintRelationId, AccessShareLock);
  	conscan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId, true,
  								 NULL, 1, skey);
  
  	while (HeapTupleIsValid(htup = systable_getnext(conscan)))
  	{
  		Form_pg_constraint conform = (Form_pg_constraint) GETSTRUCT(htup);
  		Datum		val;
  		bool		isnull;
  
  		/* We want check constraints only */
  		if (conform->contype != CONSTRAINT_CHECK)
  			continue;
  
  		/* protect limited size of array */
  		if (found >= ncheck)
  		{
  			elog(WARNING, "unexpected pg_constraint record found for relation \"%s\"",
  				 RelationGetRelationName(relation));
  			break;
  		}
  
  		check[found].ccvalid = conform->convalidated;
  		check[found].ccnoinherit = conform->connoinherit;
  		check[found].ccname = MemoryContextStrdup(CacheMemoryContext,
  												  NameStr(conform->conname));
  
  		/* Grab and test conbin is actually set */
  		val = fastgetattr(htup,
  						  Anum_pg_constraint_conbin,
  						  conrel->rd_att, &isnull);
  		if (isnull)
  			elog(WARNING, "null conbin for relation \"%s\"",
  				 RelationGetRelationName(relation));
  		else
  		{
  			/* detoast and convert to cstring in caller's context */
  			char	   *s = TextDatumGetCString(val);
  
  			check[found].ccbin = MemoryContextStrdup(CacheMemoryContext, s);
  			pfree(s);
  			found++;
  		}
  	}
  
  	systable_endscan(conscan);
  	table_close(conrel, AccessShareLock);
  
  	if (found != ncheck)
  		elog(WARNING, "%d pg_constraint record(s) missing for relation \"%s\"",
  			 ncheck - found, RelationGetRelationName(relation));
  
  	/*
  	 * Sort the records by name.  This ensures that CHECKs are applied in a
  	 * deterministic order, and it also makes equalTupleDescs() faster.
  	 */
  	if (found > 1)
  		qsort(check, found, sizeof(ConstrCheck), CheckConstraintCmp);
  
  	/* Install array only after it's fully valid */
  	relation->rd_att->constr->check = check;
  	relation->rd_att->constr->num_check = found;
  }
  
  /*
   * qsort comparator to sort ConstrCheck entries by name
   */
  static int
  CheckConstraintCmp(const void *a, const void *b)
  {
  	const ConstrCheck *ca = (const ConstrCheck *) a;
  	const ConstrCheck *cb = (const ConstrCheck *) b;
  
  	return strcmp(ca->ccname, cb->ccname);
  }
  
  /*
   * RelationGetFKeyList -- get a list of foreign key info for the relation
   *
   * Returns a list of ForeignKeyCacheInfo structs, one per FK constraining
   * the given relation.  This data is a direct copy of relevant fields from
   * pg_constraint.  The list items are in no particular order.
   *
   * CAUTION: the returned list is part of the relcache's data, and could
   * vanish in a relcache entry reset.  Callers must inspect or copy it
   * before doing anything that might trigger a cache flush, such as
   * system catalog accesses.  copyObject() can be used if desired.
   * (We define it this way because current callers want to filter and
   * modify the list entries anyway, so copying would be a waste of time.)
   */
  List *
  RelationGetFKeyList(Relation relation)
  {
  	List	   *result;
  	Relation	conrel;
  	SysScanDesc conscan;
  	ScanKeyData skey;
  	HeapTuple	htup;
  	List	   *oldlist;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the list. */
  	if (relation->rd_fkeyvalid)
  		return relation->rd_fkeylist;
  
  	/* Fast path: non-partitioned tables without triggers can't have FKs */
  	if (!relation->rd_rel->relhastriggers &&
  		relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
  		return NIL;
  
  	/*
  	 * We build the list we intend to return (in the caller's context) while
  	 * doing the scan.  After successfully completing the scan, we copy that
  	 * list into the relcache entry.  This avoids cache-context memory leakage
  	 * if we get some sort of error partway through.
  	 */
  	result = NIL;
  
  	/* Prepare to scan pg_constraint for entries having conrelid = this rel. */
  	ScanKeyInit(&skey,
  				Anum_pg_constraint_conrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	conrel = table_open(ConstraintRelationId, AccessShareLock);
  	conscan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId, true,
  								 NULL, 1, &skey);
  
  	while (HeapTupleIsValid(htup = systable_getnext(conscan)))
  	{
  		Form_pg_constraint constraint = (Form_pg_constraint) GETSTRUCT(htup);
  		ForeignKeyCacheInfo *info;
  
  		/* consider only foreign keys */
  		if (constraint->contype != CONSTRAINT_FOREIGN)
  			continue;
  
  		info = makeNode(ForeignKeyCacheInfo);
  		info->conoid = constraint->oid;
  		info->conrelid = constraint->conrelid;
  		info->confrelid = constraint->confrelid;
  
  		DeconstructFkConstraintRow(htup, &info->nkeys,
  								   info->conkey,
  								   info->confkey,
  								   info->conpfeqop,
  								   NULL, NULL);
  
  		/* Add FK's node to the result list */
  		result = lappend(result, info);
  	}
  
  	systable_endscan(conscan);
  	table_close(conrel, AccessShareLock);
  
  	/* Now save a copy of the completed list in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  	oldlist = relation->rd_fkeylist;
  	relation->rd_fkeylist = copyObject(result);
  	relation->rd_fkeyvalid = true;
  	MemoryContextSwitchTo(oldcxt);
  
  	/* Don't leak the old list, if there is one */
  	list_free_deep(oldlist);
  
  	return result;
  }
  
  /*
   * RelationGetIndexList -- get a list of OIDs of indexes on this relation
   *
   * The index list is created only if someone requests it.  We scan pg_index
   * to find relevant indexes, and add the list to the relcache entry so that
   * we won't have to compute it again.  Note that shared cache inval of a
   * relcache entry will delete the old list and set rd_indexvalid to false,
   * so that we must recompute the index list on next request.  This handles
   * creation or deletion of an index.
   *
   * Indexes that are marked not indislive are omitted from the returned list.
   * Such indexes are expected to be dropped momentarily, and should not be
   * touched at all by any caller of this function.
   *
   * The returned list is guaranteed to be sorted in order by OID.  This is
   * needed by the executor, since for index types that we obtain exclusive
   * locks on when updating the index, all backends must lock the indexes in
   * the same order or we will get deadlocks (see ExecOpenIndices()).  Any
   * consistent ordering would do, but ordering by OID is easy.
   *
   * Since shared cache inval causes the relcache's copy of the list to go away,
   * we return a copy of the list palloc'd in the caller's context.  The caller
   * may list_free() the returned list after scanning it. This is necessary
   * since the caller will typically be doing syscache lookups on the relevant
   * indexes, and syscache lookup could cause SI messages to be processed!
   *
   * In exactly the same way, we update rd_pkindex, which is the OID of the
   * relation's primary key index if any, else InvalidOid; and rd_replidindex,
   * which is the pg_class OID of an index to be used as the relation's
   * replication identity index, or InvalidOid if there is no such index.
   */
  List *
  RelationGetIndexList(Relation relation)
  {
  	Relation	indrel;
  	SysScanDesc indscan;
  	ScanKeyData skey;
  	HeapTuple	htup;
  	List	   *result;
  	List	   *oldlist;
  	char		replident = relation->rd_rel->relreplident;
  	Oid			pkeyIndex = InvalidOid;
  	Oid			candidateIndex = InvalidOid;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the list. */
  	if (relation->rd_indexvalid)
  		return list_copy(relation->rd_indexlist);
  
  	/*
  	 * We build the list we intend to return (in the caller's context) while
  	 * doing the scan.  After successfully completing the scan, we copy that
  	 * list into the relcache entry.  This avoids cache-context memory leakage
  	 * if we get some sort of error partway through.
  	 */
  	result = NIL;
  
  	/* Prepare to scan pg_index for entries having indrelid = this rel. */
  	ScanKeyInit(&skey,
  				Anum_pg_index_indrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	indrel = table_open(IndexRelationId, AccessShareLock);
  	indscan = systable_beginscan(indrel, IndexIndrelidIndexId, true,
  								 NULL, 1, &skey);
  
  	while (HeapTupleIsValid(htup = systable_getnext(indscan)))
  	{
  		Form_pg_index index = (Form_pg_index) GETSTRUCT(htup);
  
  		/*
  		 * Ignore any indexes that are currently being dropped.  This will
  		 * prevent them from being searched, inserted into, or considered in
  		 * HOT-safety decisions.  It's unsafe to touch such an index at all
  		 * since its catalog entries could disappear at any instant.
  		 */
  		if (!index->indislive)
  			continue;
  
  		/* add index's OID to result list */
  		result = lappend_oid(result, index->indexrelid);
  
  		/*
  		 * Invalid, non-unique, non-immediate or predicate indexes aren't
  		 * interesting for either oid indexes or replication identity indexes,
  		 * so don't check them.
  		 */
  		if (!index->indisvalid || !index->indisunique ||
  			!index->indimmediate ||
  			!heap_attisnull(htup, Anum_pg_index_indpred, NULL))
  			continue;
  
  		/* remember primary key index if any */
  		if (index->indisprimary)
  			pkeyIndex = index->indexrelid;
  
  		/* remember explicitly chosen replica index */
  		if (index->indisreplident)
  			candidateIndex = index->indexrelid;
  	}
  
  	systable_endscan(indscan);
  
  	table_close(indrel, AccessShareLock);
  
  	/* Sort the result list into OID order, per API spec. */
  	list_sort(result, list_oid_cmp);
  
  	/* Now save a copy of the completed list in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  	oldlist = relation->rd_indexlist;
  	relation->rd_indexlist = list_copy(result);
  	relation->rd_pkindex = pkeyIndex;
  	if (replident == REPLICA_IDENTITY_DEFAULT && OidIsValid(pkeyIndex))
  		relation->rd_replidindex = pkeyIndex;
  	else if (replident == REPLICA_IDENTITY_INDEX && OidIsValid(candidateIndex))
  		relation->rd_replidindex = candidateIndex;
  	else
  		relation->rd_replidindex = InvalidOid;
  	relation->rd_indexvalid = true;
  	MemoryContextSwitchTo(oldcxt);
  
  	/* Don't leak the old list, if there is one */
  	list_free(oldlist);
  
  	return result;
  }
  
  /*
   * RelationGetStatExtList
   *		get a list of OIDs of statistics objects on this relation
   *
   * The statistics list is created only if someone requests it, in a way
   * similar to RelationGetIndexList().  We scan pg_statistic_ext to find
   * relevant statistics, and add the list to the relcache entry so that we
   * won't have to compute it again.  Note that shared cache inval of a
   * relcache entry will delete the old list and set rd_statvalid to 0,
   * so that we must recompute the statistics list on next request.  This
   * handles creation or deletion of a statistics object.
   *
   * The returned list is guaranteed to be sorted in order by OID, although
   * this is not currently needed.
   *
   * Since shared cache inval causes the relcache's copy of the list to go away,
   * we return a copy of the list palloc'd in the caller's context.  The caller
   * may list_free() the returned list after scanning it. This is necessary
   * since the caller will typically be doing syscache lookups on the relevant
   * statistics, and syscache lookup could cause SI messages to be processed!
   */
  List *
  RelationGetStatExtList(Relation relation)
  {
  	Relation	indrel;
  	SysScanDesc indscan;
  	ScanKeyData skey;
  	HeapTuple	htup;
  	List	   *result;
  	List	   *oldlist;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the list. */
  	if (relation->rd_statvalid != 0)
  		return list_copy(relation->rd_statlist);
  
  	/*
  	 * We build the list we intend to return (in the caller's context) while
  	 * doing the scan.  After successfully completing the scan, we copy that
  	 * list into the relcache entry.  This avoids cache-context memory leakage
  	 * if we get some sort of error partway through.
  	 */
  	result = NIL;
  
  	/*
  	 * Prepare to scan pg_statistic_ext for entries having stxrelid = this
  	 * rel.
  	 */
  	ScanKeyInit(&skey,
  				Anum_pg_statistic_ext_stxrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetRelid(relation)));
  
  	indrel = table_open(StatisticExtRelationId, AccessShareLock);
  	indscan = systable_beginscan(indrel, StatisticExtRelidIndexId, true,
  								 NULL, 1, &skey);
  
  	while (HeapTupleIsValid(htup = systable_getnext(indscan)))
  	{
  		Oid			oid = ((Form_pg_statistic_ext) GETSTRUCT(htup))->oid;
  
  		result = lappend_oid(result, oid);
  	}
  
  	systable_endscan(indscan);
  
  	table_close(indrel, AccessShareLock);
  
  	/* Sort the result list into OID order, per API spec. */
  	list_sort(result, list_oid_cmp);
  
  	/* Now save a copy of the completed list in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  	oldlist = relation->rd_statlist;
  	relation->rd_statlist = list_copy(result);
  
  	relation->rd_statvalid = true;
  	MemoryContextSwitchTo(oldcxt);
  
  	/* Don't leak the old list, if there is one */
  	list_free(oldlist);
  
  	return result;
  }
  
  /*
   * RelationGetPrimaryKeyIndex -- get OID of the relation's primary key index
   *
   * Returns InvalidOid if there is no such index.
   */
  Oid
  RelationGetPrimaryKeyIndex(Relation relation)
  {
  	List	   *ilist;
  
  	if (!relation->rd_indexvalid)
  	{
  		/* RelationGetIndexList does the heavy lifting. */
  		ilist = RelationGetIndexList(relation);
  		list_free(ilist);
  		Assert(relation->rd_indexvalid);
  	}
  
  	return relation->rd_pkindex;
  }
  
  /*
   * RelationGetReplicaIndex -- get OID of the relation's replica identity index
   *
   * Returns InvalidOid if there is no such index.
   */
  Oid
  RelationGetReplicaIndex(Relation relation)
  {
  	List	   *ilist;
  
  	if (!relation->rd_indexvalid)
  	{
  		/* RelationGetIndexList does the heavy lifting. */
  		ilist = RelationGetIndexList(relation);
  		list_free(ilist);
  		Assert(relation->rd_indexvalid);
  	}
  
  	return relation->rd_replidindex;
  }
  
  /*
   * RelationGetIndexExpressions -- get the index expressions for an index
   *
   * We cache the result of transforming pg_index.indexprs into a node tree.
   * If the rel is not an index or has no expressional columns, we return NIL.
   * Otherwise, the returned tree is copied into the caller's memory context.
   * (We don't want to return a pointer to the relcache copy, since it could
   * disappear due to relcache invalidation.)
   */
  List *
  RelationGetIndexExpressions(Relation relation)
  {
  	List	   *result;
  	Datum		exprsDatum;
  	bool		isnull;
  	char	   *exprsString;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the result. */
  	if (relation->rd_indexprs)
  		return copyObject(relation->rd_indexprs);
  
  	/* Quick exit if there is nothing to do. */
  	if (relation->rd_indextuple == NULL ||
  		heap_attisnull(relation->rd_indextuple, Anum_pg_index_indexprs, NULL))
  		return NIL;
  
  	/*
  	 * We build the tree we intend to return in the caller's context. After
  	 * successfully completing the work, we copy it into the relcache entry.
  	 * This avoids problems if we get some sort of error partway through.
  	 */
  	exprsDatum = heap_getattr(relation->rd_indextuple,
  							  Anum_pg_index_indexprs,
  							  GetPgIndexDescriptor(),
  							  &isnull);
  	Assert(!isnull);
  	exprsString = TextDatumGetCString(exprsDatum);
  	result = (List *) stringToNode(exprsString);
  	pfree(exprsString);
  
  	/*
  	 * Run the expressions through eval_const_expressions. This is not just an
  	 * optimization, but is necessary, because the planner will be comparing
  	 * them to similarly-processed qual clauses, and may fail to detect valid
  	 * matches without this.  We must not use canonicalize_qual, however,
  	 * since these aren't qual expressions.
  	 */
  	result = (List *) eval_const_expressions(NULL, (Node *) result);
  
  	/* May as well fix opfuncids too */
  	fix_opfuncids((Node *) result);
  
  	/* Now save a copy of the completed tree in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(relation->rd_indexcxt);
  	relation->rd_indexprs = copyObject(result);
  	MemoryContextSwitchTo(oldcxt);
  
  	return result;
  }
  
  /*
   * RelationGetDummyIndexExpressions -- get dummy expressions for an index
   *
   * Return a list of dummy expressions (just Const nodes) with the same
   * types/typmods/collations as the index's real expressions.  This is
   * useful in situations where we don't want to run any user-defined code.
   */
  List *
  RelationGetDummyIndexExpressions(Relation relation)
  {
  	List	   *result;
  	Datum		exprsDatum;
  	bool		isnull;
  	char	   *exprsString;
  	List	   *rawExprs;
  	ListCell   *lc;
  
  	/* Quick exit if there is nothing to do. */
  	if (relation->rd_indextuple == NULL ||
  		heap_attisnull(relation->rd_indextuple, Anum_pg_index_indexprs, NULL))
  		return NIL;
  
  	/* Extract raw node tree(s) from index tuple. */
  	exprsDatum = heap_getattr(relation->rd_indextuple,
  							  Anum_pg_index_indexprs,
  							  GetPgIndexDescriptor(),
  							  &isnull);
  	Assert(!isnull);
  	exprsString = TextDatumGetCString(exprsDatum);
  	rawExprs = (List *) stringToNode(exprsString);
  	pfree(exprsString);
  
  	/* Construct null Consts; the typlen and typbyval are arbitrary. */
  	result = NIL;
  	foreach(lc, rawExprs)
  	{
  		Node	   *rawExpr = (Node *) lfirst(lc);
  
  		result = lappend(result,
  						 makeConst(exprType(rawExpr),
  								   exprTypmod(rawExpr),
  								   exprCollation(rawExpr),
  								   1,
  								   (Datum) 0,
  								   true,
  								   true));
  	}
  
  	return result;
  }
  
  /*
   * RelationGetIndexPredicate -- get the index predicate for an index
   *
   * We cache the result of transforming pg_index.indpred into an implicit-AND
   * node tree (suitable for use in planning).
   * If the rel is not an index or has no predicate, we return NIL.
   * Otherwise, the returned tree is copied into the caller's memory context.
   * (We don't want to return a pointer to the relcache copy, since it could
   * disappear due to relcache invalidation.)
   */
  List *
  RelationGetIndexPredicate(Relation relation)
  {
  	List	   *result;
  	Datum		predDatum;
  	bool		isnull;
  	char	   *predString;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the result. */
  	if (relation->rd_indpred)
  		return copyObject(relation->rd_indpred);
  
  	/* Quick exit if there is nothing to do. */
  	if (relation->rd_indextuple == NULL ||
  		heap_attisnull(relation->rd_indextuple, Anum_pg_index_indpred, NULL))
  		return NIL;
  
  	/*
  	 * We build the tree we intend to return in the caller's context. After
  	 * successfully completing the work, we copy it into the relcache entry.
  	 * This avoids problems if we get some sort of error partway through.
  	 */
  	predDatum = heap_getattr(relation->rd_indextuple,
  							 Anum_pg_index_indpred,
  							 GetPgIndexDescriptor(),
  							 &isnull);
  	Assert(!isnull);
  	predString = TextDatumGetCString(predDatum);
  	result = (List *) stringToNode(predString);
  	pfree(predString);
  
  	/*
  	 * Run the expression through const-simplification and canonicalization.
  	 * This is not just an optimization, but is necessary, because the planner
  	 * will be comparing it to similarly-processed qual clauses, and may fail
  	 * to detect valid matches without this.  This must match the processing
  	 * done to qual clauses in preprocess_expression()!  (We can skip the
  	 * stuff involving subqueries, however, since we don't allow any in index
  	 * predicates.)
  	 */
  	result = (List *) eval_const_expressions(NULL, (Node *) result);
  
  	result = (List *) canonicalize_qual((Expr *) result, false);
  
  	/* Also convert to implicit-AND format */
  	result = make_ands_implicit((Expr *) result);
  
  	/* May as well fix opfuncids too */
  	fix_opfuncids((Node *) result);
  
  	/* Now save a copy of the completed tree in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(relation->rd_indexcxt);
  	relation->rd_indpred = copyObject(result);
  	MemoryContextSwitchTo(oldcxt);
  
  	return result;
  }
  
  /*
   * RelationGetIndexAttrBitmap -- get a bitmap of index attribute numbers
   *
   * The result has a bit set for each attribute used anywhere in the index
   * definitions of all the indexes on this relation.  (This includes not only
   * simple index keys, but attributes used in expressions and partial-index
   * predicates.)
   *
   * Depending on attrKind, a bitmap covering the attnums for all index columns,
   * for all potential foreign key columns, or for all columns in the configured
   * replica identity index is returned.
   *
   * Attribute numbers are offset by FirstLowInvalidHeapAttributeNumber so that
   * we can include system attributes (e.g., OID) in the bitmap representation.
   *
   * Caller had better hold at least RowExclusiveLock on the target relation
   * to ensure it is safe (deadlock-free) for us to take locks on the relation's
   * indexes.  Note that since the introduction of CREATE INDEX CONCURRENTLY,
   * that lock level doesn't guarantee a stable set of indexes, so we have to
   * be prepared to retry here in case of a change in the set of indexes.
   *
   * The returned result is palloc'd in the caller's memory context and should
   * be bms_free'd when not needed anymore.
   */
  Bitmapset *
  RelationGetIndexAttrBitmap(Relation relation, IndexAttrBitmapKind attrKind)
  {
  	Bitmapset  *indexattrs;		/* indexed columns */
  	Bitmapset  *uindexattrs;	/* columns in unique indexes */
  	Bitmapset  *pkindexattrs;	/* columns in the primary index */
  	Bitmapset  *idindexattrs;	/* columns in the replica identity */
  	List	   *indexoidlist;
  	List	   *newindexoidlist;
  	Oid			relpkindex;
  	Oid			relreplindex;
  	ListCell   *l;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the result. */
  	if (relation->rd_indexattr != NULL)
  	{
  		switch (attrKind)
  		{
  			case INDEX_ATTR_BITMAP_ALL:
  				return bms_copy(relation->rd_indexattr);
  			case INDEX_ATTR_BITMAP_KEY:
  				return bms_copy(relation->rd_keyattr);
  			case INDEX_ATTR_BITMAP_PRIMARY_KEY:
  				return bms_copy(relation->rd_pkattr);
  			case INDEX_ATTR_BITMAP_IDENTITY_KEY:
  				return bms_copy(relation->rd_idattr);
  			default:
  				elog(ERROR, "unknown attrKind %u", attrKind);
  		}
  	}
  
  	/* Fast path if definitely no indexes */
  	if (!RelationGetForm(relation)->relhasindex)
  		return NULL;
  
  	/*
  	 * Get cached list of index OIDs. If we have to start over, we do so here.
  	 */
  restart:
  	indexoidlist = RelationGetIndexList(relation);
  
  	/* Fall out if no indexes (but relhasindex was set) */
  	if (indexoidlist == NIL)
  		return NULL;
  
  	/*
  	 * Copy the rd_pkindex and rd_replidindex values computed by
  	 * RelationGetIndexList before proceeding.  This is needed because a
  	 * relcache flush could occur inside index_open below, resetting the
  	 * fields managed by RelationGetIndexList.  We need to do the work with
  	 * stable values of these fields.
  	 */
  	relpkindex = relation->rd_pkindex;
  	relreplindex = relation->rd_replidindex;
  
  	/*
  	 * For each index, add referenced attributes to indexattrs.
  	 *
  	 * Note: we consider all indexes returned by RelationGetIndexList, even if
  	 * they are not indisready or indisvalid.  This is important because an
  	 * index for which CREATE INDEX CONCURRENTLY has just started must be
  	 * included in HOT-safety decisions (see README.HOT).  If a DROP INDEX
  	 * CONCURRENTLY is far enough along that we should ignore the index, it
  	 * won't be returned at all by RelationGetIndexList.
  	 */
  	indexattrs = NULL;
  	uindexattrs = NULL;
  	pkindexattrs = NULL;
  	idindexattrs = NULL;
  	foreach(l, indexoidlist)
  	{
  		Oid			indexOid = lfirst_oid(l);
  		Relation	indexDesc;
  		Datum		datum;
  		bool		isnull;
  		Node	   *indexExpressions;
  		Node	   *indexPredicate;
  		int			i;
  		bool		isKey;		/* candidate key */
  		bool		isPK;		/* primary key */
  		bool		isIDKey;	/* replica identity index */
  
  		indexDesc = index_open(indexOid, AccessShareLock);
  
  		/*
  		 * Extract index expressions and index predicate.  Note: Don't use
  		 * RelationGetIndexExpressions()/RelationGetIndexPredicate(), because
  		 * those might run constant expressions evaluation, which needs a
  		 * snapshot, which we might not have here.  (Also, it's probably more
  		 * sound to collect the bitmaps before any transformations that might
  		 * eliminate columns, but the practical impact of this is limited.)
  		 */
  
  		datum = heap_getattr(indexDesc->rd_indextuple, Anum_pg_index_indexprs,
  							 GetPgIndexDescriptor(), &isnull);
  		if (!isnull)
  			indexExpressions = stringToNode(TextDatumGetCString(datum));
  		else
  			indexExpressions = NULL;
  
  		datum = heap_getattr(indexDesc->rd_indextuple, Anum_pg_index_indpred,
  							 GetPgIndexDescriptor(), &isnull);
  		if (!isnull)
  			indexPredicate = stringToNode(TextDatumGetCString(datum));
  		else
  			indexPredicate = NULL;
  
  		/* Can this index be referenced by a foreign key? */
  		isKey = indexDesc->rd_index->indisunique &&
  			indexExpressions == NULL &&
  			indexPredicate == NULL;
  
  		/* Is this a primary key? */
  		isPK = (indexOid == relpkindex);
  
  		/* Is this index the configured (or default) replica identity? */
  		isIDKey = (indexOid == relreplindex);
  
  		/* Collect simple attribute references */
  		for (i = 0; i < indexDesc->rd_index->indnatts; i++)
  		{
  			int			attrnum = indexDesc->rd_index->indkey.values[i];
  
  			/*
  			 * Since we have covering indexes with non-key columns, we must
  			 * handle them accurately here. non-key columns must be added into
  			 * indexattrs, since they are in index, and HOT-update shouldn't
  			 * miss them. Obviously, non-key columns couldn't be referenced by
  			 * foreign key or identity key. Hence we do not include them into
  			 * uindexattrs, pkindexattrs and idindexattrs bitmaps.
  			 */
  			if (attrnum != 0)
  			{
  				indexattrs = bms_add_member(indexattrs,
  											attrnum - FirstLowInvalidHeapAttributeNumber);
  
  				if (isKey && i < indexDesc->rd_index->indnkeyatts)
  					uindexattrs = bms_add_member(uindexattrs,
  												 attrnum - FirstLowInvalidHeapAttributeNumber);
  
  				if (isPK && i < indexDesc->rd_index->indnkeyatts)
  					pkindexattrs = bms_add_member(pkindexattrs,
  												  attrnum - FirstLowInvalidHeapAttributeNumber);
  
  				if (isIDKey && i < indexDesc->rd_index->indnkeyatts)
  					idindexattrs = bms_add_member(idindexattrs,
  												  attrnum - FirstLowInvalidHeapAttributeNumber);
  			}
  		}
  
  		/* Collect all attributes used in expressions, too */
  		pull_varattnos(indexExpressions, 1, &indexattrs);
  
  		/* Collect all attributes in the index predicate, too */
  		pull_varattnos(indexPredicate, 1, &indexattrs);
  
  		index_close(indexDesc, AccessShareLock);
  	}
  
  	/*
  	 * During one of the index_opens in the above loop, we might have received
  	 * a relcache flush event on this relcache entry, which might have been
  	 * signaling a change in the rel's index list.  If so, we'd better start
  	 * over to ensure we deliver up-to-date attribute bitmaps.
  	 */
  	newindexoidlist = RelationGetIndexList(relation);
  	if (equal(indexoidlist, newindexoidlist) &&
  		relpkindex == relation->rd_pkindex &&
  		relreplindex == relation->rd_replidindex)
  	{
  		/* Still the same index set, so proceed */
  		list_free(newindexoidlist);
  		list_free(indexoidlist);
  	}
  	else
  	{
  		/* Gotta do it over ... might as well not leak memory */
  		list_free(newindexoidlist);
  		list_free(indexoidlist);
  		bms_free(uindexattrs);
  		bms_free(pkindexattrs);
  		bms_free(idindexattrs);
  		bms_free(indexattrs);
  
  		goto restart;
  	}
  
  	/* Don't leak the old values of these bitmaps, if any */
  	bms_free(relation->rd_indexattr);
  	relation->rd_indexattr = NULL;
  	bms_free(relation->rd_keyattr);
  	relation->rd_keyattr = NULL;
  	bms_free(relation->rd_pkattr);
  	relation->rd_pkattr = NULL;
  	bms_free(relation->rd_idattr);
  	relation->rd_idattr = NULL;
  
  	/*
  	 * Now save copies of the bitmaps in the relcache entry.  We intentionally
  	 * set rd_indexattr last, because that's the one that signals validity of
  	 * the values; if we run out of memory before making that copy, we won't
  	 * leave the relcache entry looking like the other ones are valid but
  	 * empty.
  	 */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  	relation->rd_keyattr = bms_copy(uindexattrs);
  	relation->rd_pkattr = bms_copy(pkindexattrs);
  	relation->rd_idattr = bms_copy(idindexattrs);
  	relation->rd_indexattr = bms_copy(indexattrs);
  	MemoryContextSwitchTo(oldcxt);
  
  	/* We return our original working copy for caller to play with */
  	switch (attrKind)
  	{
  		case INDEX_ATTR_BITMAP_ALL:
  			return indexattrs;
  		case INDEX_ATTR_BITMAP_KEY:
  			return uindexattrs;
  		case INDEX_ATTR_BITMAP_PRIMARY_KEY:
  			return pkindexattrs;
  		case INDEX_ATTR_BITMAP_IDENTITY_KEY:
  			return idindexattrs;
  		default:
  			elog(ERROR, "unknown attrKind %u", attrKind);
  			return NULL;
  	}
  }
  
  /*
   * RelationGetIdentityKeyBitmap -- get a bitmap of replica identity attribute
   * numbers
   *
   * A bitmap of index attribute numbers for the configured replica identity
   * index is returned.
   *
   * See also comments of RelationGetIndexAttrBitmap().
   *
   * This is a special purpose function used during logical replication. Here,
   * unlike RelationGetIndexAttrBitmap(), we don't acquire a lock on the required
   * index as we build the cache entry using a historic snapshot and all the
   * later changes are absorbed while decoding WAL. Due to this reason, we don't
   * need to retry here in case of a change in the set of indexes.
   */
  Bitmapset *
  RelationGetIdentityKeyBitmap(Relation relation)
  {
  	Bitmapset  *idindexattrs = NULL;	/* columns in the replica identity */
  	Relation	indexDesc;
  	int			i;
  	Oid			replidindex;
  	MemoryContext oldcxt;
  
  	/* Quick exit if we already computed the result */
  	if (relation->rd_idattr != NULL)
  		return bms_copy(relation->rd_idattr);
  
  	/* Fast path if definitely no indexes */
  	if (!RelationGetForm(relation)->relhasindex)
  		return NULL;
  
  	/* Historic snapshot must be set. */
  	Assert(HistoricSnapshotActive());
  
  	replidindex = RelationGetReplicaIndex(relation);
  
  	/* Fall out if there is no replica identity index */
  	if (!OidIsValid(replidindex))
  		return NULL;
  
  	/* Look up the description for the replica identity index */
  	indexDesc = RelationIdGetRelation(replidindex);
  
  	if (!RelationIsValid(indexDesc))
  		elog(ERROR, "could not open relation with OID %u",
  			 relation->rd_replidindex);
  
  	/* Add referenced attributes to idindexattrs */
  	for (i = 0; i < indexDesc->rd_index->indnatts; i++)
  	{
  		int			attrnum = indexDesc->rd_index->indkey.values[i];
  
  		/*
  		 * We don't include non-key columns into idindexattrs bitmaps. See
  		 * RelationGetIndexAttrBitmap.
  		 */
  		if (attrnum != 0)
  		{
  			if (i < indexDesc->rd_index->indnkeyatts)
  				idindexattrs = bms_add_member(idindexattrs,
  											  attrnum - FirstLowInvalidHeapAttributeNumber);
  		}
  	}
  
  	RelationClose(indexDesc);
  
  	/* Don't leak the old values of these bitmaps, if any */
  	bms_free(relation->rd_idattr);
  	relation->rd_idattr = NULL;
  
  	/* Now save copy of the bitmap in the relcache entry */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  	relation->rd_idattr = bms_copy(idindexattrs);
  	MemoryContextSwitchTo(oldcxt);
  
  	/* We return our original working copy for caller to play with */
  	return idindexattrs;
  }
  
  /*
   * RelationGetExclusionInfo -- get info about index's exclusion constraint
   *
   * This should be called only for an index that is known to have an
   * associated exclusion constraint.  It returns arrays (palloc'd in caller's
   * context) of the exclusion operator OIDs, their underlying functions'
   * OIDs, and their strategy numbers in the index's opclasses.  We cache
   * all this information since it requires a fair amount of work to get.
   */
  void
  RelationGetExclusionInfo(Relation indexRelation,
  						 Oid **operators,
  						 Oid **procs,
  						 uint16 **strategies)
  {
  	int			indnkeyatts;
  	Oid		   *ops;
  	Oid		   *funcs;
  	uint16	   *strats;
  	Relation	conrel;
  	SysScanDesc conscan;
  	ScanKeyData skey[1];
  	HeapTuple	htup;
  	bool		found;
  	MemoryContext oldcxt;
  	int			i;
  
  	indnkeyatts = IndexRelationGetNumberOfKeyAttributes(indexRelation);
  
  	/* Allocate result space in caller context */
  	*operators = ops = (Oid *) palloc(sizeof(Oid) * indnkeyatts);
  	*procs = funcs = (Oid *) palloc(sizeof(Oid) * indnkeyatts);
  	*strategies = strats = (uint16 *) palloc(sizeof(uint16) * indnkeyatts);
  
  	/* Quick exit if we have the data cached already */
  	if (indexRelation->rd_exclstrats != NULL)
  	{
  		memcpy(ops, indexRelation->rd_exclops, sizeof(Oid) * indnkeyatts);
  		memcpy(funcs, indexRelation->rd_exclprocs, sizeof(Oid) * indnkeyatts);
  		memcpy(strats, indexRelation->rd_exclstrats, sizeof(uint16) * indnkeyatts);
  		return;
  	}
  
  	/*
  	 * Search pg_constraint for the constraint associated with the index. To
  	 * make this not too painfully slow, we use the index on conrelid; that
  	 * will hold the parent relation's OID not the index's own OID.
  	 *
  	 * Note: if we wanted to rely on the constraint name matching the index's
  	 * name, we could just do a direct lookup using pg_constraint's unique
  	 * index.  For the moment it doesn't seem worth requiring that.
  	 */
  	ScanKeyInit(&skey[0],
  				Anum_pg_constraint_conrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(indexRelation->rd_index->indrelid));
  
  	conrel = table_open(ConstraintRelationId, AccessShareLock);
  	conscan = systable_beginscan(conrel, ConstraintRelidTypidNameIndexId, true,
  								 NULL, 1, skey);
  	found = false;
  
  	while (HeapTupleIsValid(htup = systable_getnext(conscan)))
  	{
  		Form_pg_constraint conform = (Form_pg_constraint) GETSTRUCT(htup);
  		Datum		val;
  		bool		isnull;
  		ArrayType  *arr;
  		int			nelem;
  
  		/* We want the exclusion constraint owning the index */
  		if (conform->contype != CONSTRAINT_EXCLUSION ||
  			conform->conindid != RelationGetRelid(indexRelation))
  			continue;
  
  		/* There should be only one */
  		if (found)
  			elog(ERROR, "unexpected exclusion constraint record found for rel %s",
  				 RelationGetRelationName(indexRelation));
  		found = true;
  
  		/* Extract the operator OIDS from conexclop */
  		val = fastgetattr(htup,
  						  Anum_pg_constraint_conexclop,
  						  conrel->rd_att, &isnull);
  		if (isnull)
  			elog(ERROR, "null conexclop for rel %s",
  				 RelationGetRelationName(indexRelation));
  
  		arr = DatumGetArrayTypeP(val);	/* ensure not toasted */
  		nelem = ARR_DIMS(arr)[0];
  		if (ARR_NDIM(arr) != 1 ||
  			nelem != indnkeyatts ||
  			ARR_HASNULL(arr) ||
  			ARR_ELEMTYPE(arr) != OIDOID)
  			elog(ERROR, "conexclop is not a 1-D Oid array");
  
  		memcpy(ops, ARR_DATA_PTR(arr), sizeof(Oid) * indnkeyatts);
  	}
  
  	systable_endscan(conscan);
  	table_close(conrel, AccessShareLock);
  
  	if (!found)
  		elog(ERROR, "exclusion constraint record missing for rel %s",
  			 RelationGetRelationName(indexRelation));
  
  	/* We need the func OIDs and strategy numbers too */
  	for (i = 0; i < indnkeyatts; i++)
  	{
  		funcs[i] = get_opcode(ops[i]);
  		strats[i] = get_op_opfamily_strategy(ops[i],
  											 indexRelation->rd_opfamily[i]);
  		/* shouldn't fail, since it was checked at index creation */
  		if (strats[i] == InvalidStrategy)
  			elog(ERROR, "could not find strategy for operator %u in family %u",
  				 ops[i], indexRelation->rd_opfamily[i]);
  	}
  
  	/* Save a copy of the results in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(indexRelation->rd_indexcxt);
  	indexRelation->rd_exclops = (Oid *) palloc(sizeof(Oid) * indnkeyatts);
  	indexRelation->rd_exclprocs = (Oid *) palloc(sizeof(Oid) * indnkeyatts);
  	indexRelation->rd_exclstrats = (uint16 *) palloc(sizeof(uint16) * indnkeyatts);
  	memcpy(indexRelation->rd_exclops, ops, sizeof(Oid) * indnkeyatts);
  	memcpy(indexRelation->rd_exclprocs, funcs, sizeof(Oid) * indnkeyatts);
  	memcpy(indexRelation->rd_exclstrats, strats, sizeof(uint16) * indnkeyatts);
  	MemoryContextSwitchTo(oldcxt);
  }
  
  /*
   * Get publication actions for the given relation.
   */
  struct PublicationActions *
  GetRelationPublicationActions(Relation relation)
  {
  	List	   *puboids;
  	ListCell   *lc;
  	MemoryContext oldcxt;
  	PublicationActions *pubactions = palloc0(sizeof(PublicationActions));
  
  	/*
  	 * If not publishable, it publishes no actions.  (pgoutput_change() will
  	 * ignore it.)
  	 */
  	if (!is_publishable_relation(relation))
  		return pubactions;
  
  	if (relation->rd_pubactions)
  		return memcpy(pubactions, relation->rd_pubactions,
  					  sizeof(PublicationActions));
  
  	/* Fetch the publication membership info. */
  	puboids = GetRelationPublications(RelationGetRelid(relation));
  	if (relation->rd_rel->relispartition)
  	{
  		/* Add publications that the ancestors are in too. */
  		List	   *ancestors = get_partition_ancestors(RelationGetRelid(relation));
  		ListCell   *lc;
  
  		foreach(lc, ancestors)
  		{
  			Oid			ancestor = lfirst_oid(lc);
  
  			puboids = list_concat_unique_oid(puboids,
  											 GetRelationPublications(ancestor));
  		}
  	}
  	puboids = list_concat_unique_oid(puboids, GetAllTablesPublications());
  
  	foreach(lc, puboids)
  	{
  		Oid			pubid = lfirst_oid(lc);
  		HeapTuple	tup;
  		Form_pg_publication pubform;
  
  		tup = SearchSysCache1(PUBLICATIONOID, ObjectIdGetDatum(pubid));
  
  		if (!HeapTupleIsValid(tup))
  			elog(ERROR, "cache lookup failed for publication %u", pubid);
  
  		pubform = (Form_pg_publication) GETSTRUCT(tup);
  
  		pubactions->pubinsert |= pubform->pubinsert;
  		pubactions->pubupdate |= pubform->pubupdate;
  		pubactions->pubdelete |= pubform->pubdelete;
  		pubactions->pubtruncate |= pubform->pubtruncate;
  
  		ReleaseSysCache(tup);
  
  		/*
  		 * If we know everything is replicated, there is no point to check for
  		 * other publications.
  		 */
  		if (pubactions->pubinsert && pubactions->pubupdate &&
  			pubactions->pubdelete && pubactions->pubtruncate)
  			break;
  	}
  
  	if (relation->rd_pubactions)
  	{
  		pfree(relation->rd_pubactions);
  		relation->rd_pubactions = NULL;
  	}
  
  	/* Now save copy of the actions in the relcache entry. */
  	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
  	relation->rd_pubactions = palloc(sizeof(PublicationActions));
  	memcpy(relation->rd_pubactions, pubactions, sizeof(PublicationActions));
  	MemoryContextSwitchTo(oldcxt);
  
  	return pubactions;
  }
  
  /*
   * RelationGetIndexRawAttOptions -- get AM/opclass-specific options for the index
   */
  Datum *
  RelationGetIndexRawAttOptions(Relation indexrel)
  {
  	Oid			indexrelid = RelationGetRelid(indexrel);
  	int16		natts = RelationGetNumberOfAttributes(indexrel);
  	Datum	   *options = NULL;
  	int16		attnum;
  
  	for (attnum = 1; attnum <= natts; attnum++)
  	{
  		if (indexrel->rd_indam->amoptsprocnum == 0)
  			continue;
  
  		if (!OidIsValid(index_getprocid(indexrel, attnum,
  										indexrel->rd_indam->amoptsprocnum)))
  			continue;
  
  		if (!options)
  			options = palloc0(sizeof(Datum) * natts);
  
  		options[attnum - 1] = get_attoptions(indexrelid, attnum);
  	}
  
  	return options;
  }
  
  static bytea **
  CopyIndexAttOptions(bytea **srcopts, int natts)
  {
  	bytea	  **opts = palloc(sizeof(*opts) * natts);
  
  	for (int i = 0; i < natts; i++)
  	{
  		bytea	   *opt = srcopts[i];
  
  		opts[i] = !opt ? NULL : (bytea *)
  			DatumGetPointer(datumCopy(PointerGetDatum(opt), false, -1));
  	}
  
  	return opts;
  }
  
  /*
   * RelationGetIndexAttOptions
   *		get AM/opclass-specific options for an index parsed into a binary form
   */
  bytea	  **
  RelationGetIndexAttOptions(Relation relation, bool copy)
  {
  	MemoryContext oldcxt;
  	bytea	  **opts = relation->rd_opcoptions;
  	Oid			relid = RelationGetRelid(relation);
  	int			natts = RelationGetNumberOfAttributes(relation);	/* XXX
  																	 * IndexRelationGetNumberOfKeyAttributes */
  	int			i;
  
  	/* Try to copy cached options. */
  	if (opts)
  		return copy ? CopyIndexAttOptions(opts, natts) : opts;
  
  	/* Get and parse opclass options. */
  	opts = palloc0(sizeof(*opts) * natts);
  
  	for (i = 0; i < natts; i++)
  	{
  		if (criticalRelcachesBuilt && relid != AttributeRelidNumIndexId)
  		{
  			Datum		attoptions = get_attoptions(relid, i + 1);
  
  			opts[i] = index_opclass_options(relation, i + 1, attoptions, false);
  
  			if (attoptions != (Datum) 0)
  				pfree(DatumGetPointer(attoptions));
  		}
  	}
  
  	/* Copy parsed options to the cache. */
  	oldcxt = MemoryContextSwitchTo(relation->rd_indexcxt);
  	relation->rd_opcoptions = CopyIndexAttOptions(opts, natts);
  	MemoryContextSwitchTo(oldcxt);
  
  	if (copy)
  		return opts;
  
  	for (i = 0; i < natts; i++)
  	{
  		if (opts[i])
  			pfree(opts[i]);
  	}
  
  	pfree(opts);
  
  	return relation->rd_opcoptions;
  }
  
  /*
   * Routines to support ereport() reports of relation-related errors
   *
   * These could have been put into elog.c, but it seems like a module layering
   * violation to have elog.c calling relcache or syscache stuff --- and we
   * definitely don't want elog.h including rel.h.  So we put them here.
   */
  
  /*
   * errtable --- stores schema_name and table_name of a table
   * within the current errordata.
   */
  int
  errtable(Relation rel)
  {
  	err_generic_string(PG_DIAG_SCHEMA_NAME,
  					   get_namespace_name(RelationGetNamespace(rel)));
  	err_generic_string(PG_DIAG_TABLE_NAME, RelationGetRelationName(rel));
  
  	return 0;					/* return value does not matter */
  }
  
  /*
   * errtablecol --- stores schema_name, table_name and column_name
   * of a table column within the current errordata.
   *
   * The column is specified by attribute number --- for most callers, this is
   * easier and less error-prone than getting the column name for themselves.
   */
  int
  errtablecol(Relation rel, int attnum)
  {
  	TupleDesc	reldesc = RelationGetDescr(rel);
  	const char *colname;
  
  	/* Use reldesc if it's a user attribute, else consult the catalogs */
  	if (attnum > 0 && attnum <= reldesc->natts)
  		colname = NameStr(TupleDescAttr(reldesc, attnum - 1)->attname);
  	else
  		colname = get_attname(RelationGetRelid(rel), attnum, false);
  
  	return errtablecolname(rel, colname);
  }
  
  /*
   * errtablecolname --- stores schema_name, table_name and column_name
   * of a table column within the current errordata, where the column name is
   * given directly rather than extracted from the relation's catalog data.
   *
   * Don't use this directly unless errtablecol() is inconvenient for some
   * reason.  This might possibly be needed during intermediate states in ALTER
   * TABLE, for instance.
   */
  int
  errtablecolname(Relation rel, const char *colname)
  {
  	errtable(rel);
  	err_generic_string(PG_DIAG_COLUMN_NAME, colname);
  
  	return 0;					/* return value does not matter */
  }
  
  /*
   * errtableconstraint --- stores schema_name, table_name and constraint_name
   * of a table-related constraint within the current errordata.
   */
  int
  errtableconstraint(Relation rel, const char *conname)
  {
  	errtable(rel);
  	err_generic_string(PG_DIAG_CONSTRAINT_NAME, conname);
  
  	return 0;					/* return value does not matter */
  }
  
  
  /*
   *	load_relcache_init_file, write_relcache_init_file
   *
   *		In late 1992, we started regularly having databases with more than
   *		a thousand classes in them.  With this number of classes, it became
   *		critical to do indexed lookups on the system catalogs.
   *
   *		Bootstrapping these lookups is very hard.  We want to be able to
   *		use an index on pg_attribute, for example, but in order to do so,
   *		we must have read pg_attribute for the attributes in the index,
   *		which implies that we need to use the index.
   *
   *		In order to get around the problem, we do the following:
   *
   *		   +  When the database system is initialized (at initdb time), we
   *			  don't use indexes.  We do sequential scans.
   *
   *		   +  When the backend is started up in normal mode, we load an image
   *			  of the appropriate relation descriptors, in internal format,
   *			  from an initialization file in the data/base/... directory.
   *
   *		   +  If the initialization file isn't there, then we create the
   *			  relation descriptors using sequential scans and write 'em to
   *			  the initialization file for use by subsequent backends.
   *
   *		As of Postgres 9.0, there is one local initialization file in each
   *		database, plus one shared initialization file for shared catalogs.
   *
   *		We could dispense with the initialization files and just build the
   *		critical reldescs the hard way on every backend startup, but that
   *		slows down backend startup noticeably.
   *
   *		We can in fact go further, and save more relcache entries than
   *		just the ones that are absolutely critical; this allows us to speed
   *		up backend startup by not having to build such entries the hard way.
   *		Presently, all the catalog and index entries that are referred to
   *		by catcaches are stored in the initialization files.
   *
   *		The same mechanism that detects when catcache and relcache entries
   *		need to be invalidated (due to catalog updates) also arranges to
   *		unlink the initialization files when the contents may be out of date.
   *		The files will then be rebuilt during the next backend startup.
   */
  
  /*
   * load_relcache_init_file -- attempt to load cache from the shared
   * or local cache init file
   *
   * If successful, return true and set criticalRelcachesBuilt or
   * criticalSharedRelcachesBuilt to true.
   * If not successful, return false.
   *
   * NOTE: we assume we are already switched into CacheMemoryContext.
   */
  static bool
  load_relcache_init_file(bool shared)
  {
  	FILE	   *fp;
  	char		initfilename[MAXPGPATH];
  	Relation   *rels;
  	int			relno,
  				num_rels,
  				max_rels,
  				nailed_rels,
  				nailed_indexes,
  				magic;
  	int			i;
  
  	if (shared)
  		snprintf(initfilename, sizeof(initfilename), "global/%s",
  				 RELCACHE_INIT_FILENAME);
  	else
  		snprintf(initfilename, sizeof(initfilename), "%s/%s",
  				 DatabasePath, RELCACHE_INIT_FILENAME);
  
  	fp = AllocateFile(initfilename, PG_BINARY_R);
  	if (fp == NULL)
  		return false;
  
  	/*
  	 * Read the index relcache entries from the file.  Note we will not enter
  	 * any of them into the cache if the read fails partway through; this
  	 * helps to guard against broken init files.
  	 */
  	max_rels = 100;
  	rels = (Relation *) palloc(max_rels * sizeof(Relation));
  	num_rels = 0;
  	nailed_rels = nailed_indexes = 0;
  
  	/* check for correct magic number (compatible version) */
  	if (fread(&magic, 1, sizeof(magic), fp) != sizeof(magic))
  		goto read_failed;
  	if (magic != RELCACHE_INIT_FILEMAGIC)
  		goto read_failed;
  
  	for (relno = 0;; relno++)
  	{
  		Size		len;
  		size_t		nread;
  		Relation	rel;
  		Form_pg_class relform;
  		bool		has_not_null;
  
  		/* first read the relation descriptor length */
  		nread = fread(&len, 1, sizeof(len), fp);
  		if (nread != sizeof(len))
  		{
  			if (nread == 0)
  				break;			/* end of file */
  			goto read_failed;
  		}
  
  		/* safety check for incompatible relcache layout */
  		if (len != sizeof(RelationData))
  			goto read_failed;
  
  		/* allocate another relcache header */
  		if (num_rels >= max_rels)
  		{
  			max_rels *= 2;
  			rels = (Relation *) repalloc(rels, max_rels * sizeof(Relation));
  		}
  
  		rel = rels[num_rels++] = (Relation) palloc(len);
  
  		/* then, read the Relation structure */
  		if (fread(rel, 1, len, fp) != len)
  			goto read_failed;
  
  		/* next read the relation tuple form */
  		if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  			goto read_failed;
  
  		relform = (Form_pg_class) palloc(len);
  		if (fread(relform, 1, len, fp) != len)
  			goto read_failed;
  
  		rel->rd_rel = relform;
  
  		/* initialize attribute tuple forms */
  		rel->rd_att = CreateTemplateTupleDesc(relform->relnatts);
  		rel->rd_att->tdrefcount = 1;	/* mark as refcounted */
  
  		rel->rd_att->tdtypeid = relform->reltype ? relform->reltype : RECORDOID;
  		rel->rd_att->tdtypmod = -1; /* just to be sure */
  
  		/* next read all the attribute tuple form data entries */
  		has_not_null = false;
  		for (i = 0; i < relform->relnatts; i++)
  		{
  			Form_pg_attribute attr = TupleDescAttr(rel->rd_att, i);
  
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  			if (len != ATTRIBUTE_FIXED_PART_SIZE)
  				goto read_failed;
  			if (fread(attr, 1, len, fp) != len)
  				goto read_failed;
  
  			has_not_null |= attr->attnotnull;
  		}
  
  		/* next read the access method specific field */
  		if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  			goto read_failed;
  		if (len > 0)
  		{
  			rel->rd_options = palloc(len);
  			if (fread(rel->rd_options, 1, len, fp) != len)
  				goto read_failed;
  			if (len != VARSIZE(rel->rd_options))
  				goto read_failed;	/* sanity check */
  		}
  		else
  		{
  			rel->rd_options = NULL;
  		}
  
  		/* mark not-null status */
  		if (has_not_null)
  		{
  			TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
  
  			constr->has_not_null = true;
  			rel->rd_att->constr = constr;
  		}
  
  		/*
  		 * If it's an index, there's more to do.  Note we explicitly ignore
  		 * partitioned indexes here.
  		 */
  		if (rel->rd_rel->relkind == RELKIND_INDEX)
  		{
  			MemoryContext indexcxt;
  			Oid		   *opfamily;
  			Oid		   *opcintype;
  			RegProcedure *support;
  			int			nsupport;
  			int16	   *indoption;
  			Oid		   *indcollation;
  
  			/* Count nailed indexes to ensure we have 'em all */
  			if (rel->rd_isnailed)
  				nailed_indexes++;
  
  			/* next, read the pg_index tuple */
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  
  			rel->rd_indextuple = (HeapTuple) palloc(len);
  			if (fread(rel->rd_indextuple, 1, len, fp) != len)
  				goto read_failed;
  
  			/* Fix up internal pointers in the tuple -- see heap_copytuple */
  			rel->rd_indextuple->t_data = (HeapTupleHeader) ((char *) rel->rd_indextuple + HEAPTUPLESIZE);
  			rel->rd_index = (Form_pg_index) GETSTRUCT(rel->rd_indextuple);
  
  			/*
  			 * prepare index info context --- parameters should match
  			 * RelationInitIndexAccessInfo
  			 */
  			indexcxt = AllocSetContextCreate(CacheMemoryContext,
  											 "index info",
  											 ALLOCSET_SMALL_SIZES);
  			rel->rd_indexcxt = indexcxt;
  			MemoryContextCopyAndSetIdentifier(indexcxt,
  											  RelationGetRelationName(rel));
  
  			/*
  			 * Now we can fetch the index AM's API struct.  (We can't store
  			 * that in the init file, since it contains function pointers that
  			 * might vary across server executions.  Fortunately, it should be
  			 * safe to call the amhandler even while bootstrapping indexes.)
  			 */
  			InitIndexAmRoutine(rel);
  
  			/* next, read the vector of opfamily OIDs */
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  
  			opfamily = (Oid *) MemoryContextAlloc(indexcxt, len);
  			if (fread(opfamily, 1, len, fp) != len)
  				goto read_failed;
  
  			rel->rd_opfamily = opfamily;
  
  			/* next, read the vector of opcintype OIDs */
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  
  			opcintype = (Oid *) MemoryContextAlloc(indexcxt, len);
  			if (fread(opcintype, 1, len, fp) != len)
  				goto read_failed;
  
  			rel->rd_opcintype = opcintype;
  
  			/* next, read the vector of support procedure OIDs */
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  			support = (RegProcedure *) MemoryContextAlloc(indexcxt, len);
  			if (fread(support, 1, len, fp) != len)
  				goto read_failed;
  
  			rel->rd_support = support;
  
  			/* next, read the vector of collation OIDs */
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  
  			indcollation = (Oid *) MemoryContextAlloc(indexcxt, len);
  			if (fread(indcollation, 1, len, fp) != len)
  				goto read_failed;
  
  			rel->rd_indcollation = indcollation;
  
  			/* finally, read the vector of indoption values */
  			if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  				goto read_failed;
  
  			indoption = (int16 *) MemoryContextAlloc(indexcxt, len);
  			if (fread(indoption, 1, len, fp) != len)
  				goto read_failed;
  
  			rel->rd_indoption = indoption;
  
  			/* finally, read the vector of opcoptions values */
  			rel->rd_opcoptions = (bytea **)
  				MemoryContextAllocZero(indexcxt, sizeof(*rel->rd_opcoptions) * relform->relnatts);
  
  			for (i = 0; i < relform->relnatts; i++)
  			{
  				if (fread(&len, 1, sizeof(len), fp) != sizeof(len))
  					goto read_failed;
  
  				if (len > 0)
  				{
  					rel->rd_opcoptions[i] = (bytea *) MemoryContextAlloc(indexcxt, len);
  					if (fread(rel->rd_opcoptions[i], 1, len, fp) != len)
  						goto read_failed;
  				}
  			}
  
  			/* set up zeroed fmgr-info vector */
  			nsupport = relform->relnatts * rel->rd_indam->amsupport;
  			rel->rd_supportinfo = (FmgrInfo *)
  				MemoryContextAllocZero(indexcxt, nsupport * sizeof(FmgrInfo));
  		}
  		else
  		{
  			/* Count nailed rels to ensure we have 'em all */
  			if (rel->rd_isnailed)
  				nailed_rels++;
  
  			/* Load table AM data */
  			if (rel->rd_rel->relkind == RELKIND_RELATION ||
  				rel->rd_rel->relkind == RELKIND_SEQUENCE ||
  				rel->rd_rel->relkind == RELKIND_TOASTVALUE ||
  				rel->rd_rel->relkind == RELKIND_MATVIEW)
  				RelationInitTableAccessMethod(rel);
  
  			Assert(rel->rd_index == NULL);
  			Assert(rel->rd_indextuple == NULL);
  			Assert(rel->rd_indexcxt == NULL);
  			Assert(rel->rd_indam == NULL);
  			Assert(rel->rd_opfamily == NULL);
  			Assert(rel->rd_opcintype == NULL);
  			Assert(rel->rd_support == NULL);
  			Assert(rel->rd_supportinfo == NULL);
  			Assert(rel->rd_indoption == NULL);
  			Assert(rel->rd_indcollation == NULL);
  			Assert(rel->rd_opcoptions == NULL);
  		}
  
  		/*
  		 * Rules and triggers are not saved (mainly because the internal
  		 * format is complex and subject to change).  They must be rebuilt if
  		 * needed by RelationCacheInitializePhase3.  This is not expected to
  		 * be a big performance hit since few system catalogs have such. Ditto
  		 * for RLS policy data, partition info, index expressions, predicates,
  		 * exclusion info, and FDW info.
  		 */
  		rel->rd_rules = NULL;
  		rel->rd_rulescxt = NULL;
  		rel->trigdesc = NULL;
  		rel->rd_rsdesc = NULL;
  		rel->rd_partkey = NULL;
  		rel->rd_partkeycxt = NULL;
  		rel->rd_partdesc = NULL;
  		rel->rd_partdesc_nodetached = NULL;
  		rel->rd_partdesc_nodetached_xmin = InvalidTransactionId;
  		rel->rd_pdcxt = NULL;
  		rel->rd_pddcxt = NULL;
  		rel->rd_partcheck = NIL;
  		rel->rd_partcheckvalid = false;
  		rel->rd_partcheckcxt = NULL;
  		rel->rd_indexprs = NIL;
  		rel->rd_indpred = NIL;
  		rel->rd_exclops = NULL;
  		rel->rd_exclprocs = NULL;
  		rel->rd_exclstrats = NULL;
  		rel->rd_fdwroutine = NULL;
  
  		/*
  		 * Reset transient-state fields in the relcache entry
  		 */
  		rel->rd_smgr = NULL;
  		if (rel->rd_isnailed)
  			rel->rd_refcnt = 1;
  		else
  			rel->rd_refcnt = 0;
  		rel->rd_indexvalid = false;
  		rel->rd_indexlist = NIL;
  		rel->rd_pkindex = InvalidOid;
  		rel->rd_replidindex = InvalidOid;
  		rel->rd_indexattr = NULL;
  		rel->rd_keyattr = NULL;
  		rel->rd_pkattr = NULL;
  		rel->rd_idattr = NULL;
  		rel->rd_pubactions = NULL;
  		rel->rd_statvalid = false;
  		rel->rd_statlist = NIL;
  		rel->rd_fkeyvalid = false;
  		rel->rd_fkeylist = NIL;
  		rel->rd_createSubid = InvalidSubTransactionId;
  		rel->rd_newRelfilenodeSubid = InvalidSubTransactionId;
  		rel->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
  		rel->rd_droppedSubid = InvalidSubTransactionId;
  		rel->rd_amcache = NULL;
  		MemSet(&rel->pgstat_info, 0, sizeof(rel->pgstat_info));
  
  		/*
  		 * Recompute lock and physical addressing info.  This is needed in
  		 * case the pg_internal.init file was copied from some other database
  		 * by CREATE DATABASE.
  		 */
  		RelationInitLockInfo(rel);
  		RelationInitPhysicalAddr(rel);
  	}
  
  	/*
  	 * We reached the end of the init file without apparent problem.  Did we
  	 * get the right number of nailed items?  This is a useful crosscheck in
  	 * case the set of critical rels or indexes changes.  However, that should
  	 * not happen in a normally-running system, so let's bleat if it does.
  	 *
  	 * For the shared init file, we're called before client authentication is
  	 * done, which means that elog(WARNING) will go only to the postmaster
  	 * log, where it's easily missed.  To ensure that developers notice bad
  	 * values of NUM_CRITICAL_SHARED_RELS/NUM_CRITICAL_SHARED_INDEXES, we put
  	 * an Assert(false) there.
  	 */
  	if (shared)
  	{
  		if (nailed_rels != NUM_CRITICAL_SHARED_RELS ||
  			nailed_indexes != NUM_CRITICAL_SHARED_INDEXES)
  		{
  			elog(WARNING, "found %d nailed shared rels and %d nailed shared indexes in init file, but expected %d and %d respectively",
  				 nailed_rels, nailed_indexes,
  				 NUM_CRITICAL_SHARED_RELS, NUM_CRITICAL_SHARED_INDEXES);
  			/* Make sure we get developers' attention about this */
  			Assert(false);
  			/* In production builds, recover by bootstrapping the relcache */
  			goto read_failed;
  		}
  	}
  	else
  	{
  		if (nailed_rels != NUM_CRITICAL_LOCAL_RELS ||
  			nailed_indexes != NUM_CRITICAL_LOCAL_INDEXES)
  		{
  			elog(WARNING, "found %d nailed rels and %d nailed indexes in init file, but expected %d and %d respectively",
  				 nailed_rels, nailed_indexes,
  				 NUM_CRITICAL_LOCAL_RELS, NUM_CRITICAL_LOCAL_INDEXES);
  			/* We don't need an Assert() in this case */
  			goto read_failed;
  		}
  	}
  
  	/*
  	 * OK, all appears well.
  	 *
  	 * Now insert all the new relcache entries into the cache.
  	 */
  	for (relno = 0; relno < num_rels; relno++)
  	{
  		RelationCacheInsert(rels[relno], false);
  	}
  
  	pfree(rels);
  	FreeFile(fp);
  
  	if (shared)
  		criticalSharedRelcachesBuilt = true;
  	else
  		criticalRelcachesBuilt = true;
  	return true;
  
  	/*
  	 * init file is broken, so do it the hard way.  We don't bother trying to
  	 * free the clutter we just allocated; it's not in the relcache so it
  	 * won't hurt.
  	 */
  read_failed:
  	pfree(rels);
  	FreeFile(fp);
  
  	return false;
  }
  
  /*
   * Write out a new initialization file with the current contents
   * of the relcache (either shared rels or local rels, as indicated).
   */
  static void
  write_relcache_init_file(bool shared)
  {
  	FILE	   *fp;
  	char		tempfilename[MAXPGPATH];
  	char		finalfilename[MAXPGPATH];
  	int			magic;
  	HASH_SEQ_STATUS status;
  	RelIdCacheEnt *idhentry;
  	int			i;
  
  	/*
  	 * If we have already received any relcache inval events, there's no
  	 * chance of succeeding so we may as well skip the whole thing.
  	 */
  	if (relcacheInvalsReceived != 0L)
  		return;
  
  	/*
  	 * We must write a temporary file and rename it into place. Otherwise,
  	 * another backend starting at about the same time might crash trying to
  	 * read the partially-complete file.
  	 */
  	if (shared)
  	{
  		snprintf(tempfilename, sizeof(tempfilename), "global/%s.%d",
  				 RELCACHE_INIT_FILENAME, MyProcPid);
  		snprintf(finalfilename, sizeof(finalfilename), "global/%s",
  				 RELCACHE_INIT_FILENAME);
  	}
  	else
  	{
  		snprintf(tempfilename, sizeof(tempfilename), "%s/%s.%d",
  				 DatabasePath, RELCACHE_INIT_FILENAME, MyProcPid);
  		snprintf(finalfilename, sizeof(finalfilename), "%s/%s",
  				 DatabasePath, RELCACHE_INIT_FILENAME);
  	}
  
  	unlink(tempfilename);		/* in case it exists w/wrong permissions */
  
  	fp = AllocateFile(tempfilename, PG_BINARY_W);
  	if (fp == NULL)
  	{
  		/*
  		 * We used to consider this a fatal error, but we might as well
  		 * continue with backend startup ...
  		 */
  		ereport(WARNING,
  				(errcode_for_file_access(),
  				 errmsg("could not create relation-cache initialization file \"%s\": %m",
  						tempfilename),
  				 errdetail("Continuing anyway, but there's something wrong.")));
  		return;
  	}
  
  	/*
  	 * Write a magic number to serve as a file version identifier.  We can
  	 * change the magic number whenever the relcache layout changes.
  	 */
  	magic = RELCACHE_INIT_FILEMAGIC;
  	if (fwrite(&magic, 1, sizeof(magic), fp) != sizeof(magic))
  		elog(FATAL, "could not write init file");
  
  	/*
  	 * Write all the appropriate reldescs (in no particular order).
  	 */
  	hash_seq_init(&status, RelationIdCache);
  
  	while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
  	{
  		Relation	rel = idhentry->reldesc;
  		Form_pg_class relform = rel->rd_rel;
  
  		/* ignore if not correct group */
  		if (relform->relisshared != shared)
  			continue;
  
  		/*
  		 * Ignore if not supposed to be in init file.  We can allow any shared
  		 * relation that's been loaded so far to be in the shared init file,
  		 * but unshared relations must be ones that should be in the local
  		 * file per RelationIdIsInInitFile.  (Note: if you want to change the
  		 * criterion for rels to be kept in the init file, see also inval.c.
  		 * The reason for filtering here is to be sure that we don't put
  		 * anything into the local init file for which a relcache inval would
  		 * not cause invalidation of that init file.)
  		 */
  		if (!shared && !RelationIdIsInInitFile(RelationGetRelid(rel)))
  		{
  			/* Nailed rels had better get stored. */
  			Assert(!rel->rd_isnailed);
  			continue;
  		}
  
  		/* first write the relcache entry proper */
  		write_item(rel, sizeof(RelationData), fp);
  
  		/* next write the relation tuple form */
  		write_item(relform, CLASS_TUPLE_SIZE, fp);
  
  		/* next, do all the attribute tuple form data entries */
  		for (i = 0; i < relform->relnatts; i++)
  		{
  			write_item(TupleDescAttr(rel->rd_att, i),
  					   ATTRIBUTE_FIXED_PART_SIZE, fp);
  		}
  
  		/* next, do the access method specific field */
  		write_item(rel->rd_options,
  				   (rel->rd_options ? VARSIZE(rel->rd_options) : 0),
  				   fp);
  
  		/*
  		 * If it's an index, there's more to do. Note we explicitly ignore
  		 * partitioned indexes here.
  		 */
  		if (rel->rd_rel->relkind == RELKIND_INDEX)
  		{
  			/* write the pg_index tuple */
  			/* we assume this was created by heap_copytuple! */
  			write_item(rel->rd_indextuple,
  					   HEAPTUPLESIZE + rel->rd_indextuple->t_len,
  					   fp);
  
  			/* next, write the vector of opfamily OIDs */
  			write_item(rel->rd_opfamily,
  					   relform->relnatts * sizeof(Oid),
  					   fp);
  
  			/* next, write the vector of opcintype OIDs */
  			write_item(rel->rd_opcintype,
  					   relform->relnatts * sizeof(Oid),
  					   fp);
  
  			/* next, write the vector of support procedure OIDs */
  			write_item(rel->rd_support,
  					   relform->relnatts * (rel->rd_indam->amsupport * sizeof(RegProcedure)),
  					   fp);
  
  			/* next, write the vector of collation OIDs */
  			write_item(rel->rd_indcollation,
  					   relform->relnatts * sizeof(Oid),
  					   fp);
  
  			/* finally, write the vector of indoption values */
  			write_item(rel->rd_indoption,
  					   relform->relnatts * sizeof(int16),
  					   fp);
  
  			Assert(rel->rd_opcoptions);
  
  			/* finally, write the vector of opcoptions values */
  			for (i = 0; i < relform->relnatts; i++)
  			{
  				bytea	   *opt = rel->rd_opcoptions[i];
  
  				write_item(opt, opt ? VARSIZE(opt) : 0, fp);
  			}
  		}
  	}
  
  	if (FreeFile(fp))
  		elog(FATAL, "could not write init file");
  
  	/*
  	 * Now we have to check whether the data we've so painstakingly
  	 * accumulated is already obsolete due to someone else's just-committed
  	 * catalog changes.  If so, we just delete the temp file and leave it to
  	 * the next backend to try again.  (Our own relcache entries will be
  	 * updated by SI message processing, but we can't be sure whether what we
  	 * wrote out was up-to-date.)
  	 *
  	 * This mustn't run concurrently with the code that unlinks an init file
  	 * and sends SI messages, so grab a serialization lock for the duration.
  	 */
  	LWLockAcquire(RelCacheInitLock, LW_EXCLUSIVE);
  
  	/* Make sure we have seen all incoming SI messages */
  	AcceptInvalidationMessages();
  
  	/*
  	 * If we have received any SI relcache invals since backend start, assume
  	 * we may have written out-of-date data.
  	 */
  	if (relcacheInvalsReceived == 0L)
  	{
  		/*
  		 * OK, rename the temp file to its final name, deleting any
  		 * previously-existing init file.
  		 *
  		 * Note: a failure here is possible under Cygwin, if some other
  		 * backend is holding open an unlinked-but-not-yet-gone init file. So
  		 * treat this as a noncritical failure; just remove the useless temp
  		 * file on failure.
  		 */
  		if (rename(tempfilename, finalfilename) < 0)
  			unlink(tempfilename);
  	}
  	else
  	{
  		/* Delete the already-obsolete temp file */
  		unlink(tempfilename);
  	}
  
  	LWLockRelease(RelCacheInitLock);
  }
  
  /* write a chunk of data preceded by its length */
  static void
  write_item(const void *data, Size len, FILE *fp)
  {
  	if (fwrite(&len, 1, sizeof(len), fp) != sizeof(len))
  		elog(FATAL, "could not write init file");
  	if (fwrite(data, 1, len, fp) != len)
  		elog(FATAL, "could not write init file");
  }
  
  /*
   * Determine whether a given relation (identified by OID) is one of the ones
   * we should store in a relcache init file.
   *
   * We must cache all nailed rels, and for efficiency we should cache every rel
   * that supports a syscache.  The former set is almost but not quite a subset
   * of the latter. The special cases are relations where
   * RelationCacheInitializePhase2/3 chooses to nail for efficiency reasons, but
   * which do not support any syscache.
   */
  bool
  RelationIdIsInInitFile(Oid relationId)
  {
  	if (relationId == SharedSecLabelRelationId ||
  		relationId == TriggerRelidNameIndexId ||
  		relationId == DatabaseNameIndexId ||
  		relationId == SharedSecLabelObjectIndexId)
  	{
  		/*
  		 * If this Assert fails, we don't need the applicable special case
  		 * anymore.
  		 */
  		Assert(!RelationSupportsSysCache(relationId));
  		return true;
  	}
  	return RelationSupportsSysCache(relationId);
  }
  
  /*
   * Invalidate (remove) the init file during commit of a transaction that
   * changed one or more of the relation cache entries that are kept in the
   * local init file.
   *
   * To be safe against concurrent inspection or rewriting of the init file,
   * we must take RelCacheInitLock, then remove the old init file, then send
   * the SI messages that include relcache inval for such relations, and then
   * release RelCacheInitLock.  This serializes the whole affair against
   * write_relcache_init_file, so that we can be sure that any other process
   * that's concurrently trying to create a new init file won't move an
   * already-stale version into place after we unlink.  Also, because we unlink
   * before sending the SI messages, a backend that's currently starting cannot
   * read the now-obsolete init file and then miss the SI messages that will
   * force it to update its relcache entries.  (This works because the backend
   * startup sequence gets into the sinval array before trying to load the init
   * file.)
   *
   * We take the lock and do the unlink in RelationCacheInitFilePreInvalidate,
   * then release the lock in RelationCacheInitFilePostInvalidate.  Caller must
   * send any pending SI messages between those calls.
   */
  void
  RelationCacheInitFilePreInvalidate(void)
  {
  	char		localinitfname[MAXPGPATH];
  	char		sharedinitfname[MAXPGPATH];
  
  	if (DatabasePath)
  		snprintf(localinitfname, sizeof(localinitfname), "%s/%s",
  				 DatabasePath, RELCACHE_INIT_FILENAME);
  	snprintf(sharedinitfname, sizeof(sharedinitfname), "global/%s",
  			 RELCACHE_INIT_FILENAME);
  
  	LWLockAcquire(RelCacheInitLock, LW_EXCLUSIVE);
  
  	/*
  	 * The files might not be there if no backend has been started since the
  	 * last removal.  But complain about failures other than ENOENT with
  	 * ERROR.  Fortunately, it's not too late to abort the transaction if we
  	 * can't get rid of the would-be-obsolete init file.
  	 */
  	if (DatabasePath)
  		unlink_initfile(localinitfname, ERROR);
  	unlink_initfile(sharedinitfname, ERROR);
  }
  
  void
  RelationCacheInitFilePostInvalidate(void)
  {
  	LWLockRelease(RelCacheInitLock);
  }
  
  /*
   * Remove the init files during postmaster startup.
   *
   * We used to keep the init files across restarts, but that is unsafe in PITR
   * scenarios, and even in simple crash-recovery cases there are windows for
   * the init files to become out-of-sync with the database.  So now we just
   * remove them during startup and expect the first backend launch to rebuild
   * them.  Of course, this has to happen in each database of the cluster.
   */
  void
  RelationCacheInitFileRemove(void)
  {
  	const char *tblspcdir = "pg_tblspc";
  	DIR		   *dir;
  	struct dirent *de;
  	char		path[MAXPGPATH + 10 + sizeof(TABLESPACE_VERSION_DIRECTORY)];
  
  	snprintf(path, sizeof(path), "global/%s",
  			 RELCACHE_INIT_FILENAME);
  	unlink_initfile(path, LOG);
  
  	/* Scan everything in the default tablespace */
  	RelationCacheInitFileRemoveInDir("base");
  
  	/* Scan the tablespace link directory to find non-default tablespaces */
  	dir = AllocateDir(tblspcdir);
  
  	while ((de = ReadDirExtended(dir, tblspcdir, LOG)) != NULL)
  	{
  		if (strspn(de->d_name, "0123456789") == strlen(de->d_name))
  		{
  			/* Scan the tablespace dir for per-database dirs */
  #ifdef ADB
  			/* Postgres-XC tablespaces include node name in path */
  			snprintf(path, sizeof(path), "%s/%s/%s_%s",
  					 tblspcdir, de->d_name, TABLESPACE_VERSION_DIRECTORY, PGXCNodeName);
  #else
  			snprintf(path, sizeof(path), "%s/%s/%s",
  					 tblspcdir, de->d_name, TABLESPACE_VERSION_DIRECTORY);
  #endif
  			RelationCacheInitFileRemoveInDir(path);
  		}
  	}
  
  	FreeDir(dir);
  }
  
  /* Process one per-tablespace directory for RelationCacheInitFileRemove */
  static void
  RelationCacheInitFileRemoveInDir(const char *tblspcpath)
  {
  	DIR		   *dir;
  	struct dirent *de;
  	char		initfilename[MAXPGPATH * 2];
  
  	/* Scan the tablespace directory to find per-database directories */
  	dir = AllocateDir(tblspcpath);
  
  	while ((de = ReadDirExtended(dir, tblspcpath, LOG)) != NULL)
  	{
  		if (strspn(de->d_name, "0123456789") == strlen(de->d_name))
  		{
  			/* Try to remove the init file in each database */
  			snprintf(initfilename, sizeof(initfilename), "%s/%s/%s",
  					 tblspcpath, de->d_name, RELCACHE_INIT_FILENAME);
  			unlink_initfile(initfilename, LOG);
  		}
  	}
  
  	FreeDir(dir);
  }
  
  static void
  unlink_initfile(const char *initfilename, int elevel)
  {
  	if (unlink(initfilename) < 0)
  	{
  		/* It might not be there, but log any error other than ENOENT */
  		if (errno != ENOENT)
  			ereport(elevel,
  					(errcode_for_file_access(),
  					 errmsg("could not remove cache file \"%s\": %m",
  							initfilename)));
  	}
  }
  