text: /*-------------------------------------------------------------------------
   *
   * indexcmds.c
   *	  POSTGRES define and remove index code.
   *
   * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/commands/indexcmds.c
   *
   *-------------------------------------------------------------------------
   */
  
  #include "postgres.h"
  
  #include "access/amapi.h"
  #include "access/heapam.h"
  #include "access/htup_details.h"
  #include "access/reloptions.h"
  #include "access/sysattr.h"
  #include "access/tableam.h"
  #include "access/xact.h"
  #include "catalog/catalog.h"
  #include "catalog/index.h"
  #include "catalog/indexing.h"
  #include "catalog/pg_am.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_inherits.h"
  #include "catalog/pg_opclass.h"
  #include "catalog/pg_opfamily.h"
  #include "catalog/pg_tablespace.h"
  #include "catalog/pg_type.h"
  #include "commands/comment.h"
  #include "commands/dbcommands.h"
  #include "commands/defrem.h"
  #include "commands/event_trigger.h"
  #include "commands/progress.h"
  #include "commands/tablecmds.h"
  #include "commands/tablespace.h"
  #include "mb/pg_wchar.h"
  #include "miscadmin.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/optimizer.h"
  #include "parser/parse_coerce.h"
  #include "parser/parse_func.h"
  #include "parser/parse_oper.h"
  #include "partitioning/partdesc.h"
  #include "pgstat.h"
  #include "rewrite/rewriteManip.h"
  #include "storage/lmgr.h"
  #include "storage/proc.h"
  #include "storage/procarray.h"
  #include "storage/sinvaladt.h"
  #include "utils/acl.h"
  #include "utils/builtins.h"
  #include "utils/fmgroids.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/partcache.h"
  #include "utils/pg_rusage.h"
  #include "utils/regproc.h"
  #include "utils/snapmgr.h"
  #include "utils/syscache.h"
  
  
  /* non-export function prototypes */
  static void CheckPredicate(Expr *predicate);
  static void ComputeIndexAttrs(IndexInfo *indexInfo,
  							  Oid *typeOidP,
  							  Oid *collationOidP,
  							  Oid *classOidP,
  							  int16 *colOptionP,
  							  List *attList,
  							  List *exclusionOpNames,
  							  Oid relId,
  							  const char *accessMethodName, Oid accessMethodId,
  							  bool amcanorder,
  							  bool isconstraint);
  static char *ChooseIndexName(const char *tabname, Oid namespaceId,
  							 List *colnames, List *exclusionOpNames,
  							 bool primary, bool isconstraint);
  static char *ChooseIndexNameAddition(List *colnames);
  static List *ChooseIndexColumnNames(List *indexElems);
  static void RangeVarCallbackForReindexIndex(const RangeVar *relation,
  											Oid relId, Oid oldRelId, void *arg);
  static bool ReindexRelationConcurrently(Oid relationOid, int options);
  
  static void ReindexPartitions(Oid relid, int options, bool isTopLevel);
  static void ReindexMultipleInternal(List *relids, int options);
  static void reindex_error_callback(void *args);
  static void update_relispartition(Oid relationId, bool newval);
  static bool CompareOpclassOptions(Datum *opts1, Datum *opts2, int natts);
  
  /*
   * callback argument type for RangeVarCallbackForReindexIndex()
   */
  struct ReindexIndexCallbackState
  {
  	int			options;		/* options from statement */
  	Oid			locked_table_oid;	/* tracks previously locked table */
  };
  
  /*
   * callback arguments for reindex_error_callback()
   */
  typedef struct ReindexErrorInfo
  {
  	char	   *relname;
  	char	   *relnamespace;
  	char		relkind;
  } ReindexErrorInfo;
  
  /*
   * CheckIndexCompatible
   *		Determine whether an existing index definition is compatible with a
   *		prospective index definition, such that the existing index storage
   *		could become the storage of the new index, avoiding a rebuild.
   *
   * 'heapRelation': the relation the index would apply to.
   * 'accessMethodName': name of the AM to use.
   * 'attributeList': a list of IndexElem specifying columns and expressions
   *		to index on.
   * 'exclusionOpNames': list of names of exclusion-constraint operators,
   *		or NIL if not an exclusion constraint.
   *
   * This is tailored to the needs of ALTER TABLE ALTER TYPE, which recreates
   * any indexes that depended on a changing column from their pg_get_indexdef
   * or pg_get_constraintdef definitions.  We omit some of the sanity checks of
   * DefineIndex.  We assume that the old and new indexes have the same number
   * of columns and that if one has an expression column or predicate, both do.
   * Errors arising from the attribute list still apply.
   *
   * Most column type changes that can skip a table rewrite do not invalidate
   * indexes.  We acknowledge this when all operator classes, collations and
   * exclusion operators match.  Though we could further permit intra-opfamily
   * changes for btree and hash indexes, that adds subtle complexity with no
   * concrete benefit for core types. Note, that INCLUDE columns aren't
   * checked by this function, for them it's enough that table rewrite is
   * skipped.
   *
   * When a comparison or exclusion operator has a polymorphic input type, the
   * actual input types must also match.  This defends against the possibility
   * that operators could vary behavior in response to get_fn_expr_argtype().
   * At present, this hazard is theoretical: check_exclusion_constraint() and
   * all core index access methods decline to set fn_expr for such calls.
   *
   * We do not yet implement a test to verify compatibility of expression
   * columns or predicates, so assume any such index is incompatible.
   */
  bool
  CheckIndexCompatible(Oid oldId,
  					 const char *accessMethodName,
  					 List *attributeList,
  					 List *exclusionOpNames)
  {
  	bool		isconstraint;
  	Oid		   *typeObjectId;
  	Oid		   *collationObjectId;
  	Oid		   *classObjectId;
  	Oid			accessMethodId;
  	Oid			relationId;
  	HeapTuple	tuple;
  	Form_pg_index indexForm;
  	Form_pg_am	accessMethodForm;
  	IndexAmRoutine *amRoutine;
  	bool		amcanorder;
  	int16	   *coloptions;
  	IndexInfo  *indexInfo;
  	int			numberOfAttributes;
  	int			old_natts;
  	bool		isnull;
  	bool		ret = true;
  	oidvector  *old_indclass;
  	oidvector  *old_indcollation;
  	Relation	irel;
  	int			i;
  	Datum		d;
  
  	/* Caller should already have the relation locked in some way. */
  	relationId = IndexGetRelation(oldId, false);
  
  	/*
  	 * We can pretend isconstraint = false unconditionally.  It only serves to
  	 * decide the text of an error message that should never happen for us.
  	 */
  	isconstraint = false;
  
  	numberOfAttributes = list_length(attributeList);
  	Assert(numberOfAttributes > 0);
  	Assert(numberOfAttributes <= INDEX_MAX_KEYS);
  
  	/* look up the access method */
  	tuple = SearchSysCache1(AMNAME, PointerGetDatum(accessMethodName));
  	if (!HeapTupleIsValid(tuple))
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  				 errmsg("access method \"%s\" does not exist",
  						accessMethodName)));
  	accessMethodForm = (Form_pg_am) GETSTRUCT(tuple);
  	accessMethodId = accessMethodForm->oid;
  	amRoutine = GetIndexAmRoutine(accessMethodForm->amhandler);
  	ReleaseSysCache(tuple);
  
  	amcanorder = amRoutine->amcanorder;
  
  	/*
  	 * Compute the operator classes, collations, and exclusion operators for
  	 * the new index, so we can test whether it's compatible with the existing
  	 * one.  Note that ComputeIndexAttrs might fail here, but that's OK:
  	 * DefineIndex would have called this function with the same arguments
  	 * later on, and it would have failed then anyway.  Our attributeList
  	 * contains only key attributes, thus we're filling ii_NumIndexAttrs and
  	 * ii_NumIndexKeyAttrs with same value.
  	 */
  	indexInfo = makeIndexInfo(numberOfAttributes, numberOfAttributes,
  							  accessMethodId, NIL, NIL, false, false, false);
  	typeObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
  	collationObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
  	classObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
  	coloptions = (int16 *) palloc(numberOfAttributes * sizeof(int16));
  	ComputeIndexAttrs(indexInfo,
  					  typeObjectId, collationObjectId, classObjectId,
  					  coloptions, attributeList,
  					  exclusionOpNames, relationId,
  					  accessMethodName, accessMethodId,
  					  amcanorder, isconstraint);
  
  
  	/* Get the soon-obsolete pg_index tuple. */
  	tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(oldId));
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "cache lookup failed for index %u", oldId);
  	indexForm = (Form_pg_index) GETSTRUCT(tuple);
  
  	/*
  	 * We don't assess expressions or predicates; assume incompatibility.
  	 * Also, if the index is invalid for any reason, treat it as incompatible.
  	 */
  	if (!(heap_attisnull(tuple, Anum_pg_index_indpred, NULL) &&
  		  heap_attisnull(tuple, Anum_pg_index_indexprs, NULL) &&
  		  indexForm->indisvalid))
  	{
  		ReleaseSysCache(tuple);
  		return false;
  	}
  
  	/* Any change in operator class or collation breaks compatibility. */
  	old_natts = indexForm->indnkeyatts;
  	Assert(old_natts == numberOfAttributes);
  
  	d = SysCacheGetAttr(INDEXRELID, tuple, Anum_pg_index_indcollation, &isnull);
  	Assert(!isnull);
  	old_indcollation = (oidvector *) DatumGetPointer(d);
  
  	d = SysCacheGetAttr(INDEXRELID, tuple, Anum_pg_index_indclass, &isnull);
  	Assert(!isnull);
  	old_indclass = (oidvector *) DatumGetPointer(d);
  
  	ret = (memcmp(old_indclass->values, classObjectId,
  				  old_natts * sizeof(Oid)) == 0 &&
  		   memcmp(old_indcollation->values, collationObjectId,
  				  old_natts * sizeof(Oid)) == 0);
  
  	ReleaseSysCache(tuple);
  
  	if (!ret)
  		return false;
  
  	/* For polymorphic opcintype, column type changes break compatibility. */
  	irel = index_open(oldId, AccessShareLock);	/* caller probably has a lock */
  	for (i = 0; i < old_natts; i++)
  	{
  		if (IsPolymorphicType(get_opclass_input_type(classObjectId[i])) &&
  			TupleDescAttr(irel->rd_att, i)->atttypid != typeObjectId[i])
  		{
  			ret = false;
  			break;
  		}
  	}
  
  	/* Any change in opclass options break compatibility. */
  	if (ret)
  	{
  		Datum	   *opclassOptions = RelationGetIndexRawAttOptions(irel);
  
  		ret = CompareOpclassOptions(opclassOptions,
  									indexInfo->ii_OpclassOptions, old_natts);
  
  		if (opclassOptions)
  			pfree(opclassOptions);
  	}
  
  	/* Any change in exclusion operator selections breaks compatibility. */
  	if (ret && indexInfo->ii_ExclusionOps != NULL)
  	{
  		Oid		   *old_operators,
  				   *old_procs;
  		uint16	   *old_strats;
  
  		RelationGetExclusionInfo(irel, &old_operators, &old_procs, &old_strats);
  		ret = memcmp(old_operators, indexInfo->ii_ExclusionOps,
  					 old_natts * sizeof(Oid)) == 0;
  
  		/* Require an exact input type match for polymorphic operators. */
  		if (ret)
  		{
  			for (i = 0; i < old_natts && ret; i++)
  			{
  				Oid			left,
  							right;
  
  				op_input_types(indexInfo->ii_ExclusionOps[i], &left, &right);
  				if ((IsPolymorphicType(left) || IsPolymorphicType(right)) &&
  					TupleDescAttr(irel->rd_att, i)->atttypid != typeObjectId[i])
  				{
  					ret = false;
  					break;
  				}
  			}
  		}
  	}
  
  	index_close(irel, NoLock);
  	return ret;
  }
  
  /*
   * CompareOpclassOptions
   *
   * Compare per-column opclass options which are represented by arrays of text[]
   * datums.  Both elements of arrays and array themselves can be NULL.
   */
  static bool
  CompareOpclassOptions(Datum *opts1, Datum *opts2, int natts)
  {
  	int			i;
  
  	if (!opts1 && !opts2)
  		return true;
  
  	for (i = 0; i < natts; i++)
  	{
  		Datum		opt1 = opts1 ? opts1[i] : (Datum) 0;
  		Datum		opt2 = opts2 ? opts2[i] : (Datum) 0;
  
  		if (opt1 == (Datum) 0)
  		{
  			if (opt2 == (Datum) 0)
  				continue;
  			else
  				return false;
  		}
  		else if (opt2 == (Datum) 0)
  			return false;
  
  		/* Compare non-NULL text[] datums. */
  		if (!DatumGetBool(DirectFunctionCall2(array_eq, opt1, opt2)))
  			return false;
  	}
  
  	return true;
  }
  
  /*
   * WaitForOlderSnapshots
   *
   * Wait for transactions that might have an older snapshot than the given xmin
   * limit, because it might not contain tuples deleted just before it has
   * been taken. Obtain a list of VXIDs of such transactions, and wait for them
   * individually. This is used when building an index concurrently.
   *
   * We can exclude any running transactions that have xmin > the xmin given;
   * their oldest snapshot must be newer than our xmin limit.
   * We can also exclude any transactions that have xmin = zero, since they
   * evidently have no live snapshot at all (and any one they might be in
   * process of taking is certainly newer than ours).  Transactions in other
   * DBs can be ignored too, since they'll never even be able to see the
   * index being worked on.
   *
   * We can also exclude autovacuum processes and processes running manual
   * lazy VACUUMs, because they won't be fazed by missing index entries
   * either.  (Manual ANALYZEs, however, can't be excluded because they
   * might be within transactions that are going to do arbitrary operations
   * later.)
   *
   * Also, GetCurrentVirtualXIDs never reports our own vxid, so we need not
   * check for that.
   *
   * If a process goes idle-in-transaction with xmin zero, we do not need to
   * wait for it anymore, per the above argument.  We do not have the
   * infrastructure right now to stop waiting if that happens, but we can at
   * least avoid the folly of waiting when it is idle at the time we would
   * begin to wait.  We do this by repeatedly rechecking the output of
   * GetCurrentVirtualXIDs.  If, during any iteration, a particular vxid
   * doesn't show up in the output, we know we can forget about it.
   */
  static void
  WaitForOlderSnapshots(TransactionId limitXmin, bool progress)
  {
  	int			n_old_snapshots;
  	int			i;
  	VirtualTransactionId *old_snapshots;
  
  	old_snapshots = GetCurrentVirtualXIDs(limitXmin, true, false,
  										  PROC_IS_AUTOVACUUM | PROC_IN_VACUUM,
  										  &n_old_snapshots);
  	if (progress)
  		pgstat_progress_update_param(PROGRESS_WAITFOR_TOTAL, n_old_snapshots);
  
  	for (i = 0; i < n_old_snapshots; i++)
  	{
  		if (!VirtualTransactionIdIsValid(old_snapshots[i]))
  			continue;			/* found uninteresting in previous cycle */
  
  		if (i > 0)
  		{
  			/* see if anything's changed ... */
  			VirtualTransactionId *newer_snapshots;
  			int			n_newer_snapshots;
  			int			j;
  			int			k;
  
  			newer_snapshots = GetCurrentVirtualXIDs(limitXmin,
  													true, false,
  													PROC_IS_AUTOVACUUM | PROC_IN_VACUUM,
  													&n_newer_snapshots);
  			for (j = i; j < n_old_snapshots; j++)
  			{
  				if (!VirtualTransactionIdIsValid(old_snapshots[j]))
  					continue;	/* found uninteresting in previous cycle */
  				for (k = 0; k < n_newer_snapshots; k++)
  				{
  					if (VirtualTransactionIdEquals(old_snapshots[j],
  												   newer_snapshots[k]))
  						break;
  				}
  				if (k >= n_newer_snapshots) /* not there anymore */
  					SetInvalidVirtualTransactionId(old_snapshots[j]);
  			}
  			pfree(newer_snapshots);
  		}
  
  		if (VirtualTransactionIdIsValid(old_snapshots[i]))
  		{
  			/* If requested, publish who we're going to wait for. */
  			if (progress)
  			{
  				PGPROC	   *holder = BackendIdGetProc(old_snapshots[i].backendId);
  
  				if (holder)
  					pgstat_progress_update_param(PROGRESS_WAITFOR_CURRENT_PID,
  												 holder->pid);
  			}
  			VirtualXactLock(old_snapshots[i], true);
  		}
  
  		if (progress)
  			pgstat_progress_update_param(PROGRESS_WAITFOR_DONE, i + 1);
  	}
  }
  
  
  /*
   * DefineIndex
   *		Creates a new index.
   *
   * 'relationId': the OID of the heap relation on which the index is to be
   *		created
   * 'stmt': IndexStmt describing the properties of the new index.
   * 'indexRelationId': normally InvalidOid, but during bootstrap can be
   *		nonzero to specify a preselected OID for the index.
   * 'parentIndexId': the OID of the parent index; InvalidOid if not the child
   *		of a partitioned index.
   * 'parentConstraintId': the OID of the parent constraint; InvalidOid if not
   *		the child of a constraint (only used when recursing)
   * 'is_alter_table': this is due to an ALTER rather than a CREATE operation.
   * 'check_rights': check for CREATE rights in namespace and tablespace.  (This
   *		should be true except when ALTER is deleting/recreating an index.)
   * 'check_not_in_use': check for table not already in use in current session.
   *		This should be true unless caller is holding the table open, in which
   *		case the caller had better have checked it earlier.
   * 'skip_build': make the catalog entries but don't create the index files
   * 'quiet': suppress the NOTICE chatter ordinarily provided for constraints.
   *
   * Returns the object address of the created index.
   */
  ObjectAddress
  DefineIndex(Oid relationId,
  			IndexStmt *stmt,
  			Oid indexRelationId,
  			Oid parentIndexId,
  			Oid parentConstraintId,
  			bool is_alter_table,
  			bool check_rights,
  			bool check_not_in_use,
  			bool skip_build,
  			bool quiet)
  {
  	bool		concurrent;
  	char	   *indexRelationName;
  	char	   *accessMethodName;
  	Oid		   *typeObjectId;
  	Oid		   *collationObjectId;
  	Oid		   *classObjectId;
  	Oid			accessMethodId;
  	Oid			namespaceId;
  	Oid			tablespaceId;
  	Oid			createdConstraintId = InvalidOid;
  	List	   *indexColNames;
  	List	   *allIndexParams;
  	Relation	rel;
  	HeapTuple	tuple;
  	Form_pg_am	accessMethodForm;
  	IndexAmRoutine *amRoutine;
  	bool		amcanorder;
  	amoptions_function amoptions;
  	bool		partitioned;
  	Datum		reloptions;
  	int16	   *coloptions;
  	IndexInfo  *indexInfo;
  	bits16		flags;
  	bits16		constr_flags;
  	int			numberOfAttributes;
  	int			numberOfKeyAttributes;
  	TransactionId limitXmin;
  	ObjectAddress address;
  	LockRelId	heaprelid;
  	LOCKTAG		heaplocktag;
  	LOCKMODE	lockmode;
  	Snapshot	snapshot;
  	int			save_nestlevel = -1;
  	int			i;
  
  	/*
  	 * Some callers need us to run with an empty default_tablespace; this is a
  	 * necessary hack to be able to reproduce catalog state accurately when
  	 * recreating indexes after table-rewriting ALTER TABLE.
  	 */
  	if (stmt->reset_default_tblspc)
  	{
  		save_nestlevel = NewGUCNestLevel();
  		(void) set_config_option("default_tablespace", "",
  								 PGC_USERSET, PGC_S_SESSION,
  								 GUC_ACTION_SAVE, true, 0, false);
  	}
  
  	/*
  	 * Force non-concurrent build on temporary relations, even if CONCURRENTLY
  	 * was requested.  Other backends can't access a temporary relation, so
  	 * there's no harm in grabbing a stronger lock, and a non-concurrent DROP
  	 * is more efficient.  Do this before any use of the concurrent option is
  	 * done.
  	 */
  	if (stmt->concurrent && get_rel_persistence(relationId) != RELPERSISTENCE_TEMP)
  		concurrent = true;
  	else
  		concurrent = false;
  
  	/*
  	 * Start progress report.  If we're building a partition, this was already
  	 * done.
  	 */
  	if (!OidIsValid(parentIndexId))
  	{
  		pgstat_progress_start_command(PROGRESS_COMMAND_CREATE_INDEX,
  									  relationId);
  		pgstat_progress_update_param(PROGRESS_CREATEIDX_COMMAND,
  									 concurrent ?
  									 PROGRESS_CREATEIDX_COMMAND_CREATE_CONCURRENTLY :
  									 PROGRESS_CREATEIDX_COMMAND_CREATE);
  	}
  
  	/*
  	 * No index OID to report yet
  	 */
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_INDEX_OID,
  								 InvalidOid);
  
  	/*
  	 * count key attributes in index
  	 */
  	numberOfKeyAttributes = list_length(stmt->indexParams);
  
  	/*
  	 * Calculate the new list of index columns including both key columns and
  	 * INCLUDE columns.  Later we can determine which of these are key
  	 * columns, and which are just part of the INCLUDE list by checking the
  	 * list position.  A list item in a position less than ii_NumIndexKeyAttrs
  	 * is part of the key columns, and anything equal to and over is part of
  	 * the INCLUDE columns.
  	 */
  	allIndexParams = list_concat_copy(stmt->indexParams,
  									  stmt->indexIncludingParams);
  	numberOfAttributes = list_length(allIndexParams);
  
  	if (numberOfAttributes <= 0)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  				 errmsg("must specify at least one column")));
  	if (numberOfAttributes > INDEX_MAX_KEYS)
  		ereport(ERROR,
  				(errcode(ERRCODE_TOO_MANY_COLUMNS),
  				 errmsg("cannot use more than %d columns in an index",
  						INDEX_MAX_KEYS)));
  
  	/*
  	 * Only SELECT ... FOR UPDATE/SHARE are allowed while doing a standard
  	 * index build; but for concurrent builds we allow INSERT/UPDATE/DELETE
  	 * (but not VACUUM).
  	 *
  	 * NB: Caller is responsible for making sure that relationId refers to the
  	 * relation on which the index should be built; except in bootstrap mode,
  	 * this will typically require the caller to have already locked the
  	 * relation.  To avoid lock upgrade hazards, that lock should be at least
  	 * as strong as the one we take here.
  	 *
  	 * NB: If the lock strength here ever changes, code that is run by
  	 * parallel workers under the control of certain particular ambuild
  	 * functions will need to be updated, too.
  	 */
  	lockmode = concurrent ? ShareUpdateExclusiveLock : ShareLock;
  	rel = table_open(relationId, lockmode);
  
  	namespaceId = RelationGetNamespace(rel);
  
  	/* Ensure that it makes sense to index this kind of relation */
  	switch (rel->rd_rel->relkind)
  	{
  		case RELKIND_RELATION:
  		case RELKIND_MATVIEW:
  		case RELKIND_PARTITIONED_TABLE:
  			/* OK */
  			break;
  		case RELKIND_FOREIGN_TABLE:
  
  			/*
  			 * Custom error message for FOREIGN TABLE since the term is close
  			 * to a regular table and can confuse the user.
  			 */
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("cannot create index on foreign table \"%s\"",
  							RelationGetRelationName(rel))));
  			break;
  		default:
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("\"%s\" is not a table or materialized view",
  							RelationGetRelationName(rel))));
  			break;
  	}
  
  	/*
  	 * Establish behavior for partitioned tables, and verify sanity of
  	 * parameters.
  	 *
  	 * We do not build an actual index in this case; we only create a few
  	 * catalog entries.  The actual indexes are built by recursing for each
  	 * partition.
  	 */
  	partitioned = rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE;
  	if (partitioned)
  	{
  		/*
  		 * Note: we check 'stmt->concurrent' rather than 'concurrent', so that
  		 * the error is thrown also for temporary tables.  Seems better to be
  		 * consistent, even though we could do it on temporary table because
  		 * we're not actually doing it concurrently.
  		 */
  		if (stmt->concurrent)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot create index on partitioned table \"%s\" concurrently",
  							RelationGetRelationName(rel))));
  		if (stmt->excludeOpNames)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot create exclusion constraints on partitioned table \"%s\"",
  							RelationGetRelationName(rel))));
  	}
  
  	/*
  	 * Don't try to CREATE INDEX on temp tables of other backends.
  	 */
  	if (RELATION_IS_OTHER_TEMP(rel))
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("cannot create indexes on temporary tables of other sessions")));
  
  	/*
  	 * Unless our caller vouches for having checked this already, insist that
  	 * the table not be in use by our own session, either.  Otherwise we might
  	 * fail to make entries in the new index (for instance, if an INSERT or
  	 * UPDATE is in progress and has already made its list of target indexes).
  	 */
  	if (check_not_in_use)
  		CheckTableNotInUse(rel, "CREATE INDEX");
  
  	/*
  	 * Verify we (still) have CREATE rights in the rel's namespace.
  	 * (Presumably we did when the rel was created, but maybe not anymore.)
  	 * Skip check if caller doesn't want it.  Also skip check if
  	 * bootstrapping, since permissions machinery may not be working yet.
  	 */
  	if (check_rights && !IsBootstrapProcessingMode())
  	{
  		AclResult	aclresult;
  
  		aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
  										  ACL_CREATE);
  		if (aclresult != ACLCHECK_OK)
  			aclcheck_error(aclresult, OBJECT_SCHEMA,
  						   get_namespace_name(namespaceId));
  	}
  
  	/*
  	 * Select tablespace to use.  If not specified, use default tablespace
  	 * (which may in turn default to database's default).
  	 */
  	if (stmt->tableSpace)
  	{
  		tablespaceId = get_tablespace_oid(stmt->tableSpace, false);
  		if (partitioned && tablespaceId == MyDatabaseTableSpace)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cannot specify default tablespace for partitioned relations")));
  	}
  	else
  	{
  		tablespaceId = GetDefaultTablespace(rel->rd_rel->relpersistence,
  											partitioned);
  		/* note InvalidOid is OK in this case */
  	}
  
  	/* Check tablespace permissions */
  	if (check_rights &&
  		OidIsValid(tablespaceId) && tablespaceId != MyDatabaseTableSpace)
  	{
  		AclResult	aclresult;
  
  		aclresult = pg_tablespace_aclcheck(tablespaceId, GetUserId(),
  										   ACL_CREATE);
  		if (aclresult != ACLCHECK_OK)
  			aclcheck_error(aclresult, OBJECT_TABLESPACE,
  						   get_tablespace_name(tablespaceId));
  	}
  
  	/*
  	 * Force shared indexes into the pg_global tablespace.  This is a bit of a
  	 * hack but seems simpler than marking them in the BKI commands.  On the
  	 * other hand, if it's not shared, don't allow it to be placed there.
  	 */
  	if (rel->rd_rel->relisshared)
  		tablespaceId = GLOBALTABLESPACE_OID;
  	else if (tablespaceId == GLOBALTABLESPACE_OID)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("only shared relations can be placed in pg_global tablespace")));
  
  	/*
  	 * Choose the index column names.
  	 */
  	indexColNames = ChooseIndexColumnNames(allIndexParams);
  
  	/*
  	 * Select name for index if caller didn't specify
  	 */
  	indexRelationName = stmt->idxname;
  	if (indexRelationName == NULL)
  		indexRelationName = ChooseIndexName(RelationGetRelationName(rel),
  											namespaceId,
  											indexColNames,
  											stmt->excludeOpNames,
  											stmt->primary,
  											stmt->isconstraint);
  
  	/*
  	 * look up the access method, verify it can handle the requested features
  	 */
  	accessMethodName = stmt->accessMethod;
  	tuple = SearchSysCache1(AMNAME, PointerGetDatum(accessMethodName));
  	if (!HeapTupleIsValid(tuple))
  	{
  		/*
  		 * Hack to provide more-or-less-transparent updating of old RTREE
  		 * indexes to GiST: if RTREE is requested and not found, use GIST.
  		 */
  		if (strcmp(accessMethodName, "rtree") == 0)
  		{
  			ereport(NOTICE,
  					(errmsg("substituting access method \"gist\" for obsolete method \"rtree\"")));
  			accessMethodName = "gist";
  			tuple = SearchSysCache1(AMNAME, PointerGetDatum(accessMethodName));
  		}
  
  		if (!HeapTupleIsValid(tuple))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("access method \"%s\" does not exist",
  							accessMethodName)));
  	}
  	accessMethodForm = (Form_pg_am) GETSTRUCT(tuple);
  	accessMethodId = accessMethodForm->oid;
  	amRoutine = GetIndexAmRoutine(accessMethodForm->amhandler);
  
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_ACCESS_METHOD_OID,
  								 accessMethodId);
  
  	if (stmt->unique && !amRoutine->amcanunique)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("access method \"%s\" does not support unique indexes",
  						accessMethodName)));
  	if (stmt->indexIncludingParams != NIL && !amRoutine->amcaninclude)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("access method \"%s\" does not support included columns",
  						accessMethodName)));
  	if (numberOfAttributes > 1 && !amRoutine->amcanmulticol)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("access method \"%s\" does not support multicolumn indexes",
  						accessMethodName)));
  	if (stmt->excludeOpNames && amRoutine->amgettuple == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("access method \"%s\" does not support exclusion constraints",
  						accessMethodName)));
  
  	amcanorder = amRoutine->amcanorder;
  	amoptions = amRoutine->amoptions;
  
  	pfree(amRoutine);
  	ReleaseSysCache(tuple);
  
  	/*
  	 * Validate predicate, if given
  	 */
  	if (stmt->whereClause)
  		CheckPredicate((Expr *) stmt->whereClause);
  
  	/*
  	 * Parse AM-specific options, convert to text array form, validate.
  	 */
  	reloptions = transformRelOptions((Datum) 0, stmt->options,
  									 NULL, NULL, false, false);
  
  	(void) index_reloptions(amoptions, reloptions, true);
  
  	/*
  	 * Prepare arguments for index_create, primarily an IndexInfo structure.
  	 * Note that predicates must be in implicit-AND format.  In a concurrent
  	 * build, mark it not-ready-for-inserts.
  	 */
  	indexInfo = makeIndexInfo(numberOfAttributes,
  							  numberOfKeyAttributes,
  							  accessMethodId,
  							  NIL,	/* expressions, NIL for now */
  							  make_ands_implicit((Expr *) stmt->whereClause),
  							  stmt->unique,
  							  !concurrent,
  							  concurrent);
  
  	typeObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
  	collationObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
  	classObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
  	coloptions = (int16 *) palloc(numberOfAttributes * sizeof(int16));
  	ComputeIndexAttrs(indexInfo,
  					  typeObjectId, collationObjectId, classObjectId,
  					  coloptions, allIndexParams,
  					  stmt->excludeOpNames, relationId,
  					  accessMethodName, accessMethodId,
  					  amcanorder, stmt->isconstraint);
  
  	/*
  	 * Extra checks when creating a PRIMARY KEY index.
  	 */
  	if (stmt->primary)
  		index_check_primary_key(rel, indexInfo, is_alter_table, stmt);
  
  	/*
  	 * If this table is partitioned and we're creating a unique index or a
  	 * primary key, make sure that the partition key is a subset of the
  	 * index's columns.  Otherwise it would be possible to violate uniqueness
  	 * by putting values that ought to be unique in different partitions.
  	 *
  	 * We could lift this limitation if we had global indexes, but those have
  	 * their own problems, so this is a useful feature combination.
  	 */
  	if (partitioned && (stmt->unique || stmt->primary))
  	{
  		PartitionKey key = RelationGetPartitionKey(rel);
  		const char *constraint_type;
  		int			i;
  
  		if (stmt->primary)
  			constraint_type = "PRIMARY KEY";
  		else if (stmt->unique)
  			constraint_type = "UNIQUE";
  		else if (stmt->excludeOpNames != NIL)
  			constraint_type = "EXCLUDE";
  		else
  		{
  			elog(ERROR, "unknown constraint type");
  			constraint_type = NULL; /* keep compiler quiet */
  		}
  
  		/*
  		 * Verify that all the columns in the partition key appear in the
  		 * unique key definition, with the same notion of equality.
  		 */
  		for (i = 0; i < key->partnatts; i++)
  		{
  			bool		found = false;
  			int			eq_strategy;
  			Oid			ptkey_eqop;
  			int			j;
  
  			/*
  			 * Identify the equality operator associated with this partkey
  			 * column.  For list and range partitioning, partkeys use btree
  			 * operator classes; hash partitioning uses hash operator classes.
  			 * (Keep this in sync with ComputePartitionAttrs!)
  			 */
  			if (key->strategy == PARTITION_STRATEGY_HASH)
  				eq_strategy = HTEqualStrategyNumber;
  			else
  				eq_strategy = BTEqualStrategyNumber;
  
  			ptkey_eqop = get_opfamily_member(key->partopfamily[i],
  											 key->partopcintype[i],
  											 key->partopcintype[i],
  											 eq_strategy);
  			if (!OidIsValid(ptkey_eqop))
  				elog(ERROR, "missing operator %d(%u,%u) in partition opfamily %u",
  					 eq_strategy, key->partopcintype[i], key->partopcintype[i],
  					 key->partopfamily[i]);
  
  			/*
  			 * We'll need to be able to identify the equality operators
  			 * associated with index columns, too.  We know what to do with
  			 * btree opclasses; if there are ever any other index types that
  			 * support unique indexes, this logic will need extension.
  			 */
  			if (accessMethodId == BTREE_AM_OID)
  				eq_strategy = BTEqualStrategyNumber;
  			else
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot match partition key to an index using access method \"%s\"",
  								accessMethodName)));
  
  			/*
  			 * It may be possible to support UNIQUE constraints when partition
  			 * keys are expressions, but is it worth it?  Give up for now.
  			 */
  			if (key->partattrs[i] == 0)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("unsupported %s constraint with partition key definition",
  								constraint_type),
  						 errdetail("%s constraints cannot be used when partition keys include expressions.",
  								   constraint_type)));
  
  			/* Search the index column(s) for a match */
  			for (j = 0; j < indexInfo->ii_NumIndexKeyAttrs; j++)
  			{
  				if (key->partattrs[i] == indexInfo->ii_IndexAttrNumbers[j])
  				{
  					/* Matched the column, now what about the equality op? */
  					Oid			idx_opfamily;
  					Oid			idx_opcintype;
  
  					if (get_opclass_opfamily_and_input_type(classObjectId[j],
  															&idx_opfamily,
  															&idx_opcintype))
  					{
  						Oid			idx_eqop;
  
  						idx_eqop = get_opfamily_member(idx_opfamily,
  													   idx_opcintype,
  													   idx_opcintype,
  													   eq_strategy);
  						if (ptkey_eqop == idx_eqop)
  						{
  							found = true;
  							break;
  						}
  					}
  				}
  			}
  
  			if (!found)
  			{
  				Form_pg_attribute att;
  
  				att = TupleDescAttr(RelationGetDescr(rel),
  									key->partattrs[i] - 1);
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("unique constraint on partitioned table must include all partitioning columns"),
  						 errdetail("%s constraint on table \"%s\" lacks column \"%s\" which is part of the partition key.",
  								   constraint_type, RelationGetRelationName(rel),
  								   NameStr(att->attname))));
  			}
  		}
  	}
  
  
  	/*
  	 * We disallow indexes on system columns.  They would not necessarily get
  	 * updated correctly, and they don't seem useful anyway.
  	 */
  	for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
  	{
  		AttrNumber	attno = indexInfo->ii_IndexAttrNumbers[i];
  
  		if (attno < 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("index creation on system columns is not supported")));
  	}
  
  	/*
  	 * Also check for system columns used in expressions or predicates.
  	 */
  	if (indexInfo->ii_Expressions || indexInfo->ii_Predicate)
  	{
  		Bitmapset  *indexattrs = NULL;
  
  		pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs);
  		pull_varattnos((Node *) indexInfo->ii_Predicate, 1, &indexattrs);
  
  		for (i = FirstLowInvalidHeapAttributeNumber + 1; i < 0; i++)
  		{
  			if (bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
  							  indexattrs))
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("index creation on system columns is not supported")));
  		}
  	}
  
  	/*
  	 * Report index creation if appropriate (delay this till after most of the
  	 * error checks)
  	 */
  	if (stmt->isconstraint && !quiet)
  	{
  		const char *constraint_type;
  
  		if (stmt->primary)
  			constraint_type = "PRIMARY KEY";
  		else if (stmt->unique)
  			constraint_type = "UNIQUE";
  		else if (stmt->excludeOpNames != NIL)
  			constraint_type = "EXCLUDE";
  		else
  		{
  			elog(ERROR, "unknown constraint type");
  			constraint_type = NULL; /* keep compiler quiet */
  		}
  
  		ereport(DEBUG1,
  				(errmsg("%s %s will create implicit index \"%s\" for table \"%s\"",
  						is_alter_table ? "ALTER TABLE / ADD" : "CREATE TABLE /",
  						constraint_type,
  						indexRelationName, RelationGetRelationName(rel))));
  	}
  
  	/*
  	 * A valid stmt->oldNode implies that we already have a built form of the
  	 * index.  The caller should also decline any index build.
  	 */
  	Assert(!OidIsValid(stmt->oldNode) || (skip_build && !concurrent));
  
  	/*
  	 * Make the catalog entries for the index, including constraints. This
  	 * step also actually builds the index, except if caller requested not to
  	 * or in concurrent mode, in which case it'll be done later, or doing a
  	 * partitioned index (because those don't have storage).
  	 */
  	flags = constr_flags = 0;
  	if (stmt->isconstraint)
  		flags |= INDEX_CREATE_ADD_CONSTRAINT;
  	if (skip_build || concurrent || partitioned)
  		flags |= INDEX_CREATE_SKIP_BUILD;
  	if (stmt->if_not_exists)
  		flags |= INDEX_CREATE_IF_NOT_EXISTS;
  	if (concurrent)
  		flags |= INDEX_CREATE_CONCURRENT;
  	if (partitioned)
  		flags |= INDEX_CREATE_PARTITIONED;
  	if (stmt->primary)
  		flags |= INDEX_CREATE_IS_PRIMARY;
  
  	/*
  	 * If the table is partitioned, and recursion was declined but partitions
  	 * exist, mark the index as invalid.
  	 */
  	if (partitioned && stmt->relation && !stmt->relation->inh)
  	{
  		PartitionDesc pd = RelationGetPartitionDesc(rel);
  
  		if (pd->nparts != 0)
  			flags |= INDEX_CREATE_INVALID;
  	}
  
  	if (stmt->deferrable)
  		constr_flags |= INDEX_CONSTR_CREATE_DEFERRABLE;
  	if (stmt->initdeferred)
  		constr_flags |= INDEX_CONSTR_CREATE_INIT_DEFERRED;
  
  	indexRelationId =
  		index_create(rel, indexRelationName, indexRelationId, parentIndexId,
  					 parentConstraintId,
  					 stmt->oldNode, indexInfo, indexColNames,
  					 accessMethodId, tablespaceId,
  					 collationObjectId, classObjectId,
  					 coloptions, reloptions,
  					 flags, constr_flags,
  					 allowSystemTableMods, !check_rights,
  					 &createdConstraintId);
  
  	ObjectAddressSet(address, RelationRelationId, indexRelationId);
  
  	/*
  	 * Revert to original default_tablespace.  Must do this before any return
  	 * from this function, but after index_create, so this is a good time.
  	 */
  	if (save_nestlevel >= 0)
  		AtEOXact_GUC(true, save_nestlevel);
  
  	if (!OidIsValid(indexRelationId))
  	{
  		table_close(rel, NoLock);
  
  		/* If this is the top-level index, we're done */
  		if (!OidIsValid(parentIndexId))
  			pgstat_progress_end_command();
  
  		return address;
  	}
  
  	/* Add any requested comment */
  	if (stmt->idxcomment != NULL)
  		CreateComments(indexRelationId, RelationRelationId, 0,
  					   stmt->idxcomment);
  
  	if (partitioned)
  	{
  		/*
  		 * Unless caller specified to skip this step (via ONLY), process each
  		 * partition to make sure they all contain a corresponding index.
  		 *
  		 * If we're called internally (no stmt->relation), recurse always.
  		 */
  		if (!stmt->relation || stmt->relation->inh)
  		{
  			PartitionDesc partdesc = RelationGetPartitionDesc(rel);
  			int			nparts = partdesc->nparts;
  			Oid		   *part_oids = palloc(sizeof(Oid) * nparts);
  			bool		invalidate_parent = false;
  			TupleDesc	parentDesc;
  			Oid		   *opfamOids;
  
  			pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_TOTAL,
  										 nparts);
  
  			memcpy(part_oids, partdesc->oids, sizeof(Oid) * nparts);
  
  			parentDesc = RelationGetDescr(rel);
  			opfamOids = palloc(sizeof(Oid) * numberOfKeyAttributes);
  			for (i = 0; i < numberOfKeyAttributes; i++)
  				opfamOids[i] = get_opclass_family(classObjectId[i]);
  
  			/*
  			 * For each partition, scan all existing indexes; if one matches
  			 * our index definition and is not already attached to some other
  			 * parent index, attach it to the one we just created.
  			 *
  			 * If none matches, build a new index by calling ourselves
  			 * recursively with the same options (except for the index name).
  			 */
  			for (i = 0; i < nparts; i++)
  			{
  				Oid			childRelid = part_oids[i];
  				Relation	childrel;
  				List	   *childidxs;
  				ListCell   *cell;
  				AttrMap    *attmap;
  				bool		found = false;
  
  				childrel = table_open(childRelid, lockmode);
  
  				/*
  				 * Don't try to create indexes on foreign tables, though. Skip
  				 * those if a regular index, or fail if trying to create a
  				 * constraint index.
  				 */
  				if (childrel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
  				{
  					if (stmt->unique || stmt->primary)
  						ereport(ERROR,
  								(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  								 errmsg("cannot create unique index on partitioned table \"%s\"",
  										RelationGetRelationName(rel)),
  								 errdetail("Table \"%s\" contains partitions that are foreign tables.",
  										   RelationGetRelationName(rel))));
  
  					table_close(childrel, lockmode);
  					continue;
  				}
  
  				childidxs = RelationGetIndexList(childrel);
  				attmap =
  					build_attrmap_by_name(RelationGetDescr(childrel),
  										  parentDesc);
  
  				foreach(cell, childidxs)
  				{
  					Oid			cldidxid = lfirst_oid(cell);
  					Relation	cldidx;
  					IndexInfo  *cldIdxInfo;
  
  					/* this index is already partition of another one */
  					if (has_superclass(cldidxid))
  						continue;
  
  					cldidx = index_open(cldidxid, lockmode);
  					cldIdxInfo = BuildIndexInfo(cldidx);
  					if (CompareIndexInfo(cldIdxInfo, indexInfo,
  										 cldidx->rd_indcollation,
  										 collationObjectId,
  										 cldidx->rd_opfamily,
  										 opfamOids,
  										 attmap))
  					{
  						Oid			cldConstrOid = InvalidOid;
  
  						/*
  						 * Found a match.
  						 *
  						 * If this index is being created in the parent
  						 * because of a constraint, then the child needs to
  						 * have a constraint also, so look for one.  If there
  						 * is no such constraint, this index is no good, so
  						 * keep looking.
  						 */
  						if (createdConstraintId != InvalidOid)
  						{
  							cldConstrOid =
  								get_relation_idx_constraint_oid(childRelid,
  																cldidxid);
  							if (cldConstrOid == InvalidOid)
  							{
  								index_close(cldidx, lockmode);
  								continue;
  							}
  						}
  
  						/* Attach index to parent and we're done. */
  						IndexSetParentIndex(cldidx, indexRelationId);
  						if (createdConstraintId != InvalidOid)
  							ConstraintSetParentConstraint(cldConstrOid,
  														  createdConstraintId,
  														  childRelid);
  
  						if (!cldidx->rd_index->indisvalid)
  							invalidate_parent = true;
  
  						found = true;
  						/* keep lock till commit */
  						index_close(cldidx, NoLock);
  						break;
  					}
  
  					index_close(cldidx, lockmode);
  				}
  
  				list_free(childidxs);
  				table_close(childrel, NoLock);
  
  				/*
  				 * If no matching index was found, create our own.
  				 */
  				if (!found)
  				{
  					IndexStmt  *childStmt = copyObject(stmt);
  					bool		found_whole_row;
  					ListCell   *lc;
  
  					/*
  					 * We can't use the same index name for the child index,
  					 * so clear idxname to let the recursive invocation choose
  					 * a new name.  Likewise, the existing target relation
  					 * field is wrong, and if indexOid or oldNode are set,
  					 * they mustn't be applied to the child either.
  					 */
  					childStmt->idxname = NULL;
  					childStmt->relation = NULL;
  					childStmt->indexOid = InvalidOid;
  					childStmt->oldNode = InvalidOid;
  					childStmt->oldCreateSubid = InvalidSubTransactionId;
  					childStmt->oldFirstRelfilenodeSubid = InvalidSubTransactionId;
  
  					/*
  					 * Adjust any Vars (both in expressions and in the index's
  					 * WHERE clause) to match the partition's column numbering
  					 * in case it's different from the parent's.
  					 */
  					foreach(lc, childStmt->indexParams)
  					{
  						IndexElem  *ielem = lfirst(lc);
  
  						/*
  						 * If the index parameter is an expression, we must
  						 * translate it to contain child Vars.
  						 */
  						if (ielem->expr)
  						{
  							ielem->expr =
  								map_variable_attnos((Node *) ielem->expr,
  													1, 0, attmap,
  													InvalidOid,
  													&found_whole_row);
  							if (found_whole_row)
  								elog(ERROR, "cannot convert whole-row table reference");
  						}
  					}
  					childStmt->whereClause =
  						map_variable_attnos(stmt->whereClause, 1, 0,
  											attmap,
  											InvalidOid, &found_whole_row);
  					if (found_whole_row)
  						elog(ERROR, "cannot convert whole-row table reference");
  
  					DefineIndex(childRelid, childStmt,
  								InvalidOid, /* no predefined OID */
  								indexRelationId,	/* this is our child */
  								createdConstraintId,
  								is_alter_table, check_rights, check_not_in_use,
  								skip_build, quiet);
  				}
  
  				pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_DONE,
  											 i + 1);
  				free_attrmap(attmap);
  			}
  
  			/*
  			 * The pg_index row we inserted for this index was marked
  			 * indisvalid=true.  But if we attached an existing index that is
  			 * invalid, this is incorrect, so update our row to invalid too.
  			 */
  			if (invalidate_parent)
  			{
  				Relation	pg_index = table_open(IndexRelationId, RowExclusiveLock);
  				HeapTuple	tup,
  							newtup;
  
  				tup = SearchSysCache1(INDEXRELID,
  									  ObjectIdGetDatum(indexRelationId));
  				if (!HeapTupleIsValid(tup))
  					elog(ERROR, "cache lookup failed for index %u",
  						 indexRelationId);
  				newtup = heap_copytuple(tup);
  				((Form_pg_index) GETSTRUCT(newtup))->indisvalid = false;
  				CatalogTupleUpdate(pg_index, &tup->t_self, newtup);
  				ReleaseSysCache(tup);
  				table_close(pg_index, RowExclusiveLock);
  				heap_freetuple(newtup);
  			}
  		}
  
  		/*
  		 * Indexes on partitioned tables are not themselves built, so we're
  		 * done here.
  		 */
  		table_close(rel, NoLock);
  		if (!OidIsValid(parentIndexId))
  			pgstat_progress_end_command();
  		return address;
  	}
  
  	if (!concurrent)
  	{
  		/* Close the heap and we're done, in the non-concurrent case */
  		table_close(rel, NoLock);
  
  		/* If this is the top-level index, we're done. */
  		if (!OidIsValid(parentIndexId))
  			pgstat_progress_end_command();
  
  		return address;
  	}
  
  	/* save lockrelid and locktag for below, then close rel */
  	heaprelid = rel->rd_lockInfo.lockRelId;
  	SET_LOCKTAG_RELATION(heaplocktag, heaprelid.dbId, heaprelid.relId);
  	table_close(rel, NoLock);
  
  	/*
  	 * For a concurrent build, it's important to make the catalog entries
  	 * visible to other transactions before we start to build the index. That
  	 * will prevent them from making incompatible HOT updates.  The new index
  	 * will be marked not indisready and not indisvalid, so that no one else
  	 * tries to either insert into it or use it for queries.
  	 *
  	 * We must commit our current transaction so that the index becomes
  	 * visible; then start another.  Note that all the data structures we just
  	 * built are lost in the commit.  The only data we keep past here are the
  	 * relation IDs.
  	 *
  	 * Before committing, get a session-level lock on the table, to ensure
  	 * that neither it nor the index can be dropped before we finish. This
  	 * cannot block, even if someone else is waiting for access, because we
  	 * already have the same lock within our transaction.
  	 *
  	 * Note: we don't currently bother with a session lock on the index,
  	 * because there are no operations that could change its state while we
  	 * hold lock on the parent table.  This might need to change later.
  	 */
  	LockRelationIdForSession(&heaprelid, ShareUpdateExclusiveLock);
  
  	PopActiveSnapshot();
  	CommitTransactionCommand();
  	StartTransactionCommand();
  
  	/*
  	 * The index is now visible, so we can report the OID.
  	 */
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_INDEX_OID,
  								 indexRelationId);
  
  	/*
  	 * Phase 2 of concurrent index build (see comments for validate_index()
  	 * for an overview of how this works)
  	 *
  	 * Now we must wait until no running transaction could have the table open
  	 * with the old list of indexes.  Use ShareLock to consider running
  	 * transactions that hold locks that permit writing to the table.  Note we
  	 * do not need to worry about xacts that open the table for writing after
  	 * this point; they will see the new index when they open it.
  	 *
  	 * Note: the reason we use actual lock acquisition here, rather than just
  	 * checking the ProcArray and sleeping, is that deadlock is possible if
  	 * one of the transactions in question is blocked trying to acquire an
  	 * exclusive lock on our table.  The lock code will detect deadlock and
  	 * error out properly.
  	 */
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_1);
  	WaitForLockers(heaplocktag, ShareLock, true);
  
  	/*
  	 * At this moment we are sure that there are no transactions with the
  	 * table open for write that don't have this new index in their list of
  	 * indexes.  We have waited out all the existing transactions and any new
  	 * transaction will have the new index in its list, but the index is still
  	 * marked as "not-ready-for-inserts".  The index is consulted while
  	 * deciding HOT-safety though.  This arrangement ensures that no new HOT
  	 * chains can be created where the new tuple and the old tuple in the
  	 * chain have different index keys.
  	 *
  	 * We now take a new snapshot, and build the index using all tuples that
  	 * are visible in this snapshot.  We can be sure that any HOT updates to
  	 * these tuples will be compatible with the index, since any updates made
  	 * by transactions that didn't know about the index are now committed or
  	 * rolled back.  Thus, each visible tuple is either the end of its
  	 * HOT-chain or the extension of the chain is HOT-safe for this index.
  	 */
  
  	/* Set ActiveSnapshot since functions in the indexes may need it */
  	PushActiveSnapshot(GetTransactionSnapshot());
  
  	/* Perform concurrent build of index */
  	index_concurrently_build(relationId, indexRelationId);
  
  	/* we can do away with our snapshot */
  	PopActiveSnapshot();
  
  	/*
  	 * Commit this transaction to make the indisready update visible.
  	 */
  	CommitTransactionCommand();
  	StartTransactionCommand();
  
  	/*
  	 * Phase 3 of concurrent index build
  	 *
  	 * We once again wait until no transaction can have the table open with
  	 * the index marked as read-only for updates.
  	 */
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_2);
  	WaitForLockers(heaplocktag, ShareLock, true);
  
  	/*
  	 * Now take the "reference snapshot" that will be used by validate_index()
  	 * to filter candidate tuples.  Beware!  There might still be snapshots in
  	 * use that treat some transaction as in-progress that our reference
  	 * snapshot treats as committed.  If such a recently-committed transaction
  	 * deleted tuples in the table, we will not include them in the index; yet
  	 * those transactions which see the deleting one as still-in-progress will
  	 * expect such tuples to be there once we mark the index as valid.
  	 *
  	 * We solve this by waiting for all endangered transactions to exit before
  	 * we mark the index as valid.
  	 *
  	 * We also set ActiveSnapshot to this snap, since functions in indexes may
  	 * need a snapshot.
  	 */
  	snapshot = RegisterSnapshot(GetTransactionSnapshot());
  	PushActiveSnapshot(snapshot);
  
  	/*
  	 * Scan the index and the heap, insert any missing index entries.
  	 */
  	validate_index(relationId, indexRelationId, snapshot);
  
  	/*
  	 * Drop the reference snapshot.  We must do this before waiting out other
  	 * snapshot holders, else we will deadlock against other processes also
  	 * doing CREATE INDEX CONCURRENTLY, which would see our snapshot as one
  	 * they must wait for.  But first, save the snapshot's xmin to use as
  	 * limitXmin for GetCurrentVirtualXIDs().
  	 */
  	limitXmin = snapshot->xmin;
  
  	PopActiveSnapshot();
  	UnregisterSnapshot(snapshot);
  
  	/*
  	 * The snapshot subsystem could still contain registered snapshots that
  	 * are holding back our process's advertised xmin; in particular, if
  	 * default_transaction_isolation = serializable, there is a transaction
  	 * snapshot that is still active.  The CatalogSnapshot is likewise a
  	 * hazard.  To ensure no deadlocks, we must commit and start yet another
  	 * transaction, and do our wait before any snapshot has been taken in it.
  	 */
  	CommitTransactionCommand();
  	StartTransactionCommand();
  
  	/* We should now definitely not be advertising any xmin. */
  	Assert(MyProc->xmin == InvalidTransactionId);
  
  	/*
  	 * The index is now valid in the sense that it contains all currently
  	 * interesting tuples.  But since it might not contain tuples deleted just
  	 * before the reference snap was taken, we have to wait out any
  	 * transactions that might have older snapshots.
  	 */
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
  	WaitForOlderSnapshots(limitXmin, true);
  
  	/*
  	 * Index can now be marked valid -- update its pg_index entry
  	 */
  	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_VALID);
  
  	/*
  	 * The pg_index update will cause backends (including this one) to update
  	 * relcache entries for the index itself, but we should also send a
  	 * relcache inval on the parent table to force replanning of cached plans.
  	 * Otherwise existing sessions might fail to use the new index where it
  	 * would be useful.  (Note that our earlier commits did not create reasons
  	 * to replan; so relcache flush on the index itself was sufficient.)
  	 */
  	CacheInvalidateRelcacheByRelid(heaprelid.relId);
  
  	/*
  	 * Last thing to do is release the session-level lock on the parent table.
  	 */
  	UnlockRelationIdForSession(&heaprelid, ShareUpdateExclusiveLock);
  
  	pgstat_progress_end_command();
  
  	return address;
  }
  
  
  /*
   * CheckMutability
   *		Test whether given expression is mutable
   */
  static bool
  CheckMutability(Expr *expr)
  {
  	/*
  	 * First run the expression through the planner.  This has a couple of
  	 * important consequences.  First, function default arguments will get
  	 * inserted, which may affect volatility (consider "default now()").
  	 * Second, inline-able functions will get inlined, which may allow us to
  	 * conclude that the function is really less volatile than it's marked. As
  	 * an example, polymorphic functions must be marked with the most volatile
  	 * behavior that they have for any input type, but once we inline the
  	 * function we may be able to conclude that it's not so volatile for the
  	 * particular input type we're dealing with.
  	 *
  	 * We assume here that expression_planner() won't scribble on its input.
  	 */
  	expr = expression_planner(expr);
  
  	/* Now we can search for non-immutable functions */
  	return contain_mutable_functions((Node *) expr);
  }
  
  
  /*
   * CheckPredicate
   *		Checks that the given partial-index predicate is valid.
   *
   * This used to also constrain the form of the predicate to forms that
   * indxpath.c could do something with.  However, that seems overly
   * restrictive.  One useful application of partial indexes is to apply
   * a UNIQUE constraint across a subset of a table, and in that scenario
   * any evaluable predicate will work.  So accept any predicate here
   * (except ones requiring a plan), and let indxpath.c fend for itself.
   */
  static void
  CheckPredicate(Expr *predicate)
  {
  	/*
  	 * transformExpr() should have already rejected subqueries, aggregates,
  	 * and window functions, based on the EXPR_KIND_ for a predicate.
  	 */
  
  	/*
  	 * A predicate using mutable functions is probably wrong, for the same
  	 * reasons that we don't allow an index expression to use one.
  	 */
  	if (CheckMutability(predicate))
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  				 errmsg("functions in index predicate must be marked IMMUTABLE")));
  }
  
  /*
   * Compute per-index-column information, including indexed column numbers
   * or index expressions, opclasses and their options. Note, all output vectors
   * should be allocated for all columns, including "including" ones.
   */
  static void
  ComputeIndexAttrs(IndexInfo *indexInfo,
  				  Oid *typeOidP,
  				  Oid *collationOidP,
  				  Oid *classOidP,
  				  int16 *colOptionP,
  				  List *attList,	/* list of IndexElem's */
  				  List *exclusionOpNames,
  				  Oid relId,
  				  const char *accessMethodName,
  				  Oid accessMethodId,
  				  bool amcanorder,
  				  bool isconstraint)
  {
  	ListCell   *nextExclOp;
  	ListCell   *lc;
  	int			attn;
  	int			nkeycols = indexInfo->ii_NumIndexKeyAttrs;
  
  	/* Allocate space for exclusion operator info, if needed */
  	if (exclusionOpNames)
  	{
  		Assert(list_length(exclusionOpNames) == nkeycols);
  		indexInfo->ii_ExclusionOps = (Oid *) palloc(sizeof(Oid) * nkeycols);
  		indexInfo->ii_ExclusionProcs = (Oid *) palloc(sizeof(Oid) * nkeycols);
  		indexInfo->ii_ExclusionStrats = (uint16 *) palloc(sizeof(uint16) * nkeycols);
  		nextExclOp = list_head(exclusionOpNames);
  	}
  	else
  		nextExclOp = NULL;
  
  	/*
  	 * process attributeList
  	 */
  	attn = 0;
  	foreach(lc, attList)
  	{
  		IndexElem  *attribute = (IndexElem *) lfirst(lc);
  		Oid			atttype;
  		Oid			attcollation;
  
  		/*
  		 * Process the column-or-expression to be indexed.
  		 */
  		if (attribute->name != NULL)
  		{
  			/* Simple index attribute */
  			HeapTuple	atttuple;
  			Form_pg_attribute attform;
  
  			Assert(attribute->expr == NULL);
  			atttuple = SearchSysCacheAttName(relId, attribute->name);
  			if (!HeapTupleIsValid(atttuple))
  			{
  				/* difference in error message spellings is historical */
  				if (isconstraint)
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("column \"%s\" named in key does not exist",
  									attribute->name)));
  				else
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("column \"%s\" does not exist",
  									attribute->name)));
  			}
  			attform = (Form_pg_attribute) GETSTRUCT(atttuple);
  			indexInfo->ii_IndexAttrNumbers[attn] = attform->attnum;
  			atttype = attform->atttypid;
  			attcollation = attform->attcollation;
  			ReleaseSysCache(atttuple);
  		}
  		else
  		{
  			/* Index expression */
  			Node	   *expr = attribute->expr;
  
  			Assert(expr != NULL);
  
  			if (attn >= nkeycols)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("expressions are not supported in included columns")));
  			atttype = exprType(expr);
  			attcollation = exprCollation(expr);
  
  			/*
  			 * Strip any top-level COLLATE clause.  This ensures that we treat
  			 * "x COLLATE y" and "(x COLLATE y)" alike.
  			 */
  			while (IsA(expr, CollateExpr))
  				expr = (Node *) ((CollateExpr *) expr)->arg;
  
  			if (IsA(expr, Var) &&
  				((Var *) expr)->varattno != InvalidAttrNumber)
  			{
  				/*
  				 * User wrote "(column)" or "(column COLLATE something)".
  				 * Treat it like simple attribute anyway.
  				 */
  				indexInfo->ii_IndexAttrNumbers[attn] = ((Var *) expr)->varattno;
  			}
  			else
  			{
  				indexInfo->ii_IndexAttrNumbers[attn] = 0;	/* marks expression */
  				indexInfo->ii_Expressions = lappend(indexInfo->ii_Expressions,
  													expr);
  
  				/*
  				 * transformExpr() should have already rejected subqueries,
  				 * aggregates, and window functions, based on the EXPR_KIND_
  				 * for an index expression.
  				 */
  
  				/*
  				 * An expression using mutable functions is probably wrong,
  				 * since if you aren't going to get the same result for the
  				 * same data every time, it's not clear what the index entries
  				 * mean at all.
  				 */
  				if (CheckMutability((Expr *) expr))
  					ereport(ERROR,
  							(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  							 errmsg("functions in index expression must be marked IMMUTABLE")));
  			}
  		}
  
  		typeOidP[attn] = atttype;
  
  		/*
  		 * Included columns have no collation, no opclass and no ordering
  		 * options.
  		 */
  		if (attn >= nkeycols)
  		{
  			if (attribute->collation)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  						 errmsg("including column does not support a collation")));
  			if (attribute->opclass)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  						 errmsg("including column does not support an operator class")));
  			if (attribute->ordering != SORTBY_DEFAULT)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  						 errmsg("including column does not support ASC/DESC options")));
  			if (attribute->nulls_ordering != SORTBY_NULLS_DEFAULT)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
  						 errmsg("including column does not support NULLS FIRST/LAST options")));
  
  			classOidP[attn] = InvalidOid;
  			colOptionP[attn] = 0;
  			collationOidP[attn] = InvalidOid;
  			attn++;
  
  			continue;
  		}
  
  		/*
  		 * Apply collation override if any
  		 */
  		if (attribute->collation)
  			attcollation = get_collation_oid(attribute->collation, false);
  
  		/*
  		 * Check we have a collation iff it's a collatable type.  The only
  		 * expected failures here are (1) COLLATE applied to a noncollatable
  		 * type, or (2) index expression had an unresolved collation.  But we
  		 * might as well code this to be a complete consistency check.
  		 */
  		if (type_is_collatable(atttype))
  		{
  			if (!OidIsValid(attcollation))
  				ereport(ERROR,
  						(errcode(ERRCODE_INDETERMINATE_COLLATION),
  						 errmsg("could not determine which collation to use for index expression"),
  						 errhint("Use the COLLATE clause to set the collation explicitly.")));
  		}
  		else
  		{
  			if (OidIsValid(attcollation))
  				ereport(ERROR,
  						(errcode(ERRCODE_DATATYPE_MISMATCH),
  						 errmsg("collations are not supported by type %s",
  								format_type_be(atttype))));
  		}
  
  		collationOidP[attn] = attcollation;
  
  		/*
  		 * Identify the opclass to use.
  		 */
  		classOidP[attn] = ResolveOpClass(attribute->opclass,
  										 atttype,
  										 accessMethodName,
  										 accessMethodId);
  
  		/*
  		 * Identify the exclusion operator, if any.
  		 */
  		if (nextExclOp)
  		{
  			List	   *opname = (List *) lfirst(nextExclOp);
  			Oid			opid;
  			Oid			opfamily;
  			int			strat;
  
  			/*
  			 * Find the operator --- it must accept the column datatype
  			 * without runtime coercion (but binary compatibility is OK)
  			 */
  			opid = compatible_oper_opid(opname, atttype, atttype, false);
  
  			/*
  			 * Only allow commutative operators to be used in exclusion
  			 * constraints. If X conflicts with Y, but Y does not conflict
  			 * with X, bad things will happen.
  			 */
  			if (get_commutator(opid) != opid)
  				ereport(ERROR,
  						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  						 errmsg("operator %s is not commutative",
  								format_operator(opid)),
  						 errdetail("Only commutative operators can be used in exclusion constraints.")));
  
  			/*
  			 * Operator must be a member of the right opfamily, too
  			 */
  			opfamily = get_opclass_family(classOidP[attn]);
  			strat = get_op_opfamily_strategy(opid, opfamily);
  			if (strat == 0)
  			{
  				HeapTuple	opftuple;
  				Form_pg_opfamily opfform;
  
  				/*
  				 * attribute->opclass might not explicitly name the opfamily,
  				 * so fetch the name of the selected opfamily for use in the
  				 * error message.
  				 */
  				opftuple = SearchSysCache1(OPFAMILYOID,
  										   ObjectIdGetDatum(opfamily));
  				if (!HeapTupleIsValid(opftuple))
  					elog(ERROR, "cache lookup failed for opfamily %u",
  						 opfamily);
  				opfform = (Form_pg_opfamily) GETSTRUCT(opftuple);
  
  				ereport(ERROR,
  						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  						 errmsg("operator %s is not a member of operator family \"%s\"",
  								format_operator(opid),
  								NameStr(opfform->opfname)),
  						 errdetail("The exclusion operator must be related to the index operator class for the constraint.")));
  			}
  
  			indexInfo->ii_ExclusionOps[attn] = opid;
  			indexInfo->ii_ExclusionProcs[attn] = get_opcode(opid);
  			indexInfo->ii_ExclusionStrats[attn] = strat;
  			nextExclOp = lnext(exclusionOpNames, nextExclOp);
  		}
  
  		/*
  		 * Set up the per-column options (indoption field).  For now, this is
  		 * zero for any un-ordered index, while ordered indexes have DESC and
  		 * NULLS FIRST/LAST options.
  		 */
  		colOptionP[attn] = 0;
  		if (amcanorder)
  		{
  			/* default ordering is ASC */
  			if (attribute->ordering == SORTBY_DESC)
  				colOptionP[attn] |= INDOPTION_DESC;
  			/* default null ordering is LAST for ASC, FIRST for DESC */
  			if (attribute->nulls_ordering == SORTBY_NULLS_DEFAULT)
  			{
  				if (attribute->ordering == SORTBY_DESC)
  					colOptionP[attn] |= INDOPTION_NULLS_FIRST;
  			}
  			else if (attribute->nulls_ordering == SORTBY_NULLS_FIRST)
  				colOptionP[attn] |= INDOPTION_NULLS_FIRST;
  		}
  		else
  		{
  			/* index AM does not support ordering */
  			if (attribute->ordering != SORTBY_DEFAULT)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("access method \"%s\" does not support ASC/DESC options",
  								accessMethodName)));
  			if (attribute->nulls_ordering != SORTBY_NULLS_DEFAULT)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("access method \"%s\" does not support NULLS FIRST/LAST options",
  								accessMethodName)));
  		}
  
  		/* Set up the per-column opclass options (attoptions field). */
  		if (attribute->opclassopts)
  		{
  			Assert(attn < nkeycols);
  
  			if (!indexInfo->ii_OpclassOptions)
  				indexInfo->ii_OpclassOptions =
  					palloc0(sizeof(Datum) * indexInfo->ii_NumIndexAttrs);
  
  			indexInfo->ii_OpclassOptions[attn] =
  				transformRelOptions((Datum) 0, attribute->opclassopts,
  									NULL, NULL, false, false);
  		}
  
  		attn++;
  	}
  }
  
  /*
   * Resolve possibly-defaulted operator class specification
   *
   * Note: This is used to resolve operator class specifications in index and
   * partition key definitions.
   */
  Oid
  ResolveOpClass(List *opclass, Oid attrType,
  			   const char *accessMethodName, Oid accessMethodId)
  {
  	char	   *schemaname;
  	char	   *opcname;
  	HeapTuple	tuple;
  	Form_pg_opclass opform;
  	Oid			opClassId,
  				opInputType;
  
  	if (opclass == NIL)
  	{
  		/* no operator class specified, so find the default */
  		opClassId = GetDefaultOpClass(attrType, accessMethodId);
  		if (!OidIsValid(opClassId))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("data type %s has no default operator class for access method \"%s\"",
  							format_type_be(attrType), accessMethodName),
  					 errhint("You must specify an operator class for the index or define a default operator class for the data type.")));
  		return opClassId;
  	}
  
  	/*
  	 * Specific opclass name given, so look up the opclass.
  	 */
  
  	/* deconstruct the name list */
  	DeconstructQualifiedName(opclass, &schemaname, &opcname);
  
  	if (schemaname)
  	{
  		/* Look in specific schema only */
  		Oid			namespaceId;
  
  		namespaceId = LookupExplicitNamespace(schemaname, false);
  		tuple = SearchSysCache3(CLAAMNAMENSP,
  								ObjectIdGetDatum(accessMethodId),
  								PointerGetDatum(opcname),
  								ObjectIdGetDatum(namespaceId));
  	}
  	else
  	{
  		/* Unqualified opclass name, so search the search path */
  		opClassId = OpclassnameGetOpcid(accessMethodId, opcname);
  		if (!OidIsValid(opClassId))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
  							opcname, accessMethodName)));
  		tuple = SearchSysCache1(CLAOID, ObjectIdGetDatum(opClassId));
  	}
  
  	if (!HeapTupleIsValid(tuple))
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  				 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
  						NameListToString(opclass), accessMethodName)));
  
  	/*
  	 * Verify that the index operator class accepts this datatype.  Note we
  	 * will accept binary compatibility.
  	 */
  	opform = (Form_pg_opclass) GETSTRUCT(tuple);
  	opClassId = opform->oid;
  	opInputType = opform->opcintype;
  
  	if (!IsBinaryCoercible(attrType, opInputType))
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("operator class \"%s\" does not accept data type %s",
  						NameListToString(opclass), format_type_be(attrType))));
  
  	ReleaseSysCache(tuple);
  
  	return opClassId;
  }
  
  /*
   * GetDefaultOpClass
   *
   * Given the OIDs of a datatype and an access method, find the default
   * operator class, if any.  Returns InvalidOid if there is none.
   */
  Oid
  GetDefaultOpClass(Oid type_id, Oid am_id)
  {
  	Oid			result = InvalidOid;
  	int			nexact = 0;
  	int			ncompatible = 0;
  	int			ncompatiblepreferred = 0;
  	Relation	rel;
  	ScanKeyData skey[1];
  	SysScanDesc scan;
  	HeapTuple	tup;
  	TYPCATEGORY tcategory;
  
  	/* If it's a domain, look at the base type instead */
  	type_id = getBaseType(type_id);
  
  	tcategory = TypeCategory(type_id);
  
  	/*
  	 * We scan through all the opclasses available for the access method,
  	 * looking for one that is marked default and matches the target type
  	 * (either exactly or binary-compatibly, but prefer an exact match).
  	 *
  	 * We could find more than one binary-compatible match.  If just one is
  	 * for a preferred type, use that one; otherwise we fail, forcing the user
  	 * to specify which one he wants.  (The preferred-type special case is a
  	 * kluge for varchar: it's binary-compatible to both text and bpchar, so
  	 * we need a tiebreaker.)  If we find more than one exact match, then
  	 * someone put bogus entries in pg_opclass.
  	 */
  	rel = table_open(OperatorClassRelationId, AccessShareLock);
  
  	ScanKeyInit(&skey[0],
  				Anum_pg_opclass_opcmethod,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(am_id));
  
  	scan = systable_beginscan(rel, OpclassAmNameNspIndexId, true,
  							  NULL, 1, skey);
  
  	while (HeapTupleIsValid(tup = systable_getnext(scan)))
  	{
  		Form_pg_opclass opclass = (Form_pg_opclass) GETSTRUCT(tup);
  
  		/* ignore altogether if not a default opclass */
  		if (!opclass->opcdefault)
  			continue;
  		if (opclass->opcintype == type_id)
  		{
  			nexact++;
  			result = opclass->oid;
  		}
  		else if (nexact == 0 &&
  				 IsBinaryCoercible(type_id, opclass->opcintype))
  		{
  			if (IsPreferredType(tcategory, opclass->opcintype))
  			{
  				ncompatiblepreferred++;
  				result = opclass->oid;
  			}
  			else if (ncompatiblepreferred == 0)
  			{
  				ncompatible++;
  				result = opclass->oid;
  			}
  		}
  	}
  
  	systable_endscan(scan);
  
  	table_close(rel, AccessShareLock);
  
  	/* raise error if pg_opclass contains inconsistent data */
  	if (nexact > 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_DUPLICATE_OBJECT),
  				 errmsg("there are multiple default operator classes for data type %s",
  						format_type_be(type_id))));
  
  	if (nexact == 1 ||
  		ncompatiblepreferred == 1 ||
  		(ncompatiblepreferred == 0 && ncompatible == 1))
  		return result;
  
  	return InvalidOid;
  }
  
  /*
   *	makeObjectName()
   *
   *	Create a name for an implicitly created index, sequence, constraint,
   *	extended statistics, etc.
   *
   *	The parameters are typically: the original table name, the original field
   *	name, and a "type" string (such as "seq" or "pkey").    The field name
   *	and/or type can be NULL if not relevant.
   *
   *	The result is a palloc'd string.
   *
   *	The basic result we want is "name1_name2_label", omitting "_name2" or
   *	"_label" when those parameters are NULL.  However, we must generate
   *	a name with less than NAMEDATALEN characters!  So, we truncate one or
   *	both names if necessary to make a short-enough string.  The label part
   *	is never truncated (so it had better be reasonably short).
   *
   *	The caller is responsible for checking uniqueness of the generated
   *	name and retrying as needed; retrying will be done by altering the
   *	"label" string (which is why we never truncate that part).
   */
  char *
  makeObjectName(const char *name1, const char *name2, const char *label)
  {
  	char	   *name;
  	int			overhead = 0;	/* chars needed for label and underscores */
  	int			availchars;		/* chars available for name(s) */
  	int			name1chars;		/* chars allocated to name1 */
  	int			name2chars;		/* chars allocated to name2 */
  	int			ndx;
  
  	name1chars = strlen(name1);
  	if (name2)
  	{
  		name2chars = strlen(name2);
  		overhead++;				/* allow for separating underscore */
  	}
  	else
  		name2chars = 0;
  	if (label)
  		overhead += strlen(label) + 1;
  
  	availchars = NAMEDATALEN - 1 - overhead;
  	Assert(availchars > 0);		/* else caller chose a bad label */
  
  	/*
  	 * If we must truncate,  preferentially truncate the longer name. This
  	 * logic could be expressed without a loop, but it's simple and obvious as
  	 * a loop.
  	 */
  	while (name1chars + name2chars > availchars)
  	{
  		if (name1chars > name2chars)
  			name1chars--;
  		else
  			name2chars--;
  	}
  
  	name1chars = pg_mbcliplen(name1, name1chars, name1chars);
  	if (name2)
  		name2chars = pg_mbcliplen(name2, name2chars, name2chars);
  
  	/* Now construct the string using the chosen lengths */
  	name = palloc(name1chars + name2chars + overhead + 1);
  	memcpy(name, name1, name1chars);
  	ndx = name1chars;
  	if (name2)
  	{
  		name[ndx++] = '_';
  		memcpy(name + ndx, name2, name2chars);
  		ndx += name2chars;
  	}
  	if (label)
  	{
  		name[ndx++] = '_';
  		strcpy(name + ndx, label);
  	}
  	else
  		name[ndx] = '\0';
  
  	return name;
  }
  
  /*
   * Select a nonconflicting name for a new relation.  This is ordinarily
   * used to choose index names (which is why it's here) but it can also
   * be used for sequences, or any autogenerated relation kind.
   *
   * name1, name2, and label are used the same way as for makeObjectName(),
   * except that the label can't be NULL; digits will be appended to the label
   * if needed to create a name that is unique within the specified namespace.
   *
   * If isconstraint is true, we also avoid choosing a name matching any
   * existing constraint in the same namespace.  (This is stricter than what
   * Postgres itself requires, but the SQL standard says that constraint names
   * should be unique within schemas, so we follow that for autogenerated
   * constraint names.)
   *
   * Note: it is theoretically possible to get a collision anyway, if someone
   * else chooses the same name concurrently.  This is fairly unlikely to be
   * a problem in practice, especially if one is holding an exclusive lock on
   * the relation identified by name1.  However, if choosing multiple names
   * within a single command, you'd better create the new object and do
   * CommandCounterIncrement before choosing the next one!
   *
   * Returns a palloc'd string.
   */
  char *
  ChooseRelationName(const char *name1, const char *name2,
  				   const char *label, Oid namespaceid,
  				   bool isconstraint)
  {
  	int			pass = 0;
  	char	   *relname = NULL;
  	char		modlabel[NAMEDATALEN];
  
  	/* try the unmodified label first */
  	strlcpy(modlabel, label, sizeof(modlabel));
  
  	for (;;)
  	{
  		relname = makeObjectName(name1, name2, modlabel);
  
  		if (!OidIsValid(get_relname_relid(relname, namespaceid)))
  		{
  			if (!isconstraint ||
  				!ConstraintNameExists(relname, namespaceid))
  				break;
  		}
  
  		/* found a conflict, so try a new name component */
  		pfree(relname);
  		snprintf(modlabel, sizeof(modlabel), "%s%d", label, ++pass);
  	}
  
  	return relname;
  }
  
  /*
   * Select the name to be used for an index.
   *
   * The argument list is pretty ad-hoc :-(
   */
  static char *
  ChooseIndexName(const char *tabname, Oid namespaceId,
  				List *colnames, List *exclusionOpNames,
  				bool primary, bool isconstraint)
  {
  	char	   *indexname;
  
  	if (primary)
  	{
  		/* the primary key's name does not depend on the specific column(s) */
  		indexname = ChooseRelationName(tabname,
  									   NULL,
  									   "pkey",
  									   namespaceId,
  									   true);
  	}
  	else if (exclusionOpNames != NIL)
  	{
  		indexname = ChooseRelationName(tabname,
  									   ChooseIndexNameAddition(colnames),
  									   "excl",
  									   namespaceId,
  									   true);
  	}
  	else if (isconstraint)
  	{
  		indexname = ChooseRelationName(tabname,
  									   ChooseIndexNameAddition(colnames),
  									   "key",
  									   namespaceId,
  									   true);
  	}
  	else
  	{
  		indexname = ChooseRelationName(tabname,
  									   ChooseIndexNameAddition(colnames),
  									   "idx",
  									   namespaceId,
  									   false);
  	}
  
  	return indexname;
  }
  
  /*
   * Generate "name2" for a new index given the list of column names for it
   * (as produced by ChooseIndexColumnNames).  This will be passed to
   * ChooseRelationName along with the parent table name and a suitable label.
   *
   * We know that less than NAMEDATALEN characters will actually be used,
   * so we can truncate the result once we've generated that many.
   *
   * XXX See also ChooseForeignKeyConstraintNameAddition and
   * ChooseExtendedStatisticNameAddition.
   */
  static char *
  ChooseIndexNameAddition(List *colnames)
  {
  	char		buf[NAMEDATALEN * 2];
  	int			buflen = 0;
  	ListCell   *lc;
  
  	buf[0] = '\0';
  	foreach(lc, colnames)
  	{
  		const char *name = (const char *) lfirst(lc);
  
  		if (buflen > 0)
  			buf[buflen++] = '_';	/* insert _ between names */
  
  		/*
  		 * At this point we have buflen <= NAMEDATALEN.  name should be less
  		 * than NAMEDATALEN already, but use strlcpy for paranoia.
  		 */
  		strlcpy(buf + buflen, name, NAMEDATALEN);
  		buflen += strlen(buf + buflen);
  		if (buflen >= NAMEDATALEN)
  			break;
  	}
  	return pstrdup(buf);
  }
  
  /*
   * Select the actual names to be used for the columns of an index, given the
   * list of IndexElems for the columns.  This is mostly about ensuring the
   * names are unique so we don't get a conflicting-attribute-names error.
   *
   * Returns a List of plain strings (char *, not String nodes).
   */
  static List *
  ChooseIndexColumnNames(List *indexElems)
  {
  	List	   *result = NIL;
  	ListCell   *lc;
  
  	foreach(lc, indexElems)
  	{
  		IndexElem  *ielem = (IndexElem *) lfirst(lc);
  		const char *origname;
  		const char *curname;
  		int			i;
  		char		buf[NAMEDATALEN];
  
  		/* Get the preliminary name from the IndexElem */
  		if (ielem->indexcolname)
  			origname = ielem->indexcolname; /* caller-specified name */
  		else if (ielem->name)
  			origname = ielem->name; /* simple column reference */
  		else
  			origname = "expr";	/* default name for expression */
  
  		/* If it conflicts with any previous column, tweak it */
  		curname = origname;
  		for (i = 1;; i++)
  		{
  			ListCell   *lc2;
  			char		nbuf[32];
  			int			nlen;
  
  			foreach(lc2, result)
  			{
  				if (strcmp(curname, (char *) lfirst(lc2)) == 0)
  					break;
  			}
  			if (lc2 == NULL)
  				break;			/* found nonconflicting name */
  
  			sprintf(nbuf, "%d", i);
  
  			/* Ensure generated names are shorter than NAMEDATALEN */
  			nlen = pg_mbcliplen(origname, strlen(origname),
  								NAMEDATALEN - 1 - strlen(nbuf));
  			memcpy(buf, origname, nlen);
  			strcpy(buf + nlen, nbuf);
  			curname = buf;
  		}
  
  		/* And attach to the result list */
  		result = lappend(result, pstrdup(curname));
  	}
  	return result;
  }
  
  /*
   * ReindexIndex
   *		Recreate a specific index.
   */
  void
  ReindexIndex(RangeVar *indexRelation, int options, bool isTopLevel)
  {
  	struct ReindexIndexCallbackState state;
  	Oid			indOid;
  	char		persistence;
  	char		relkind;
  
  	/*
  	 * Find and lock index, and check permissions on table; use callback to
  	 * obtain lock on table first, to avoid deadlock hazard.  The lock level
  	 * used here must match the index lock obtained in reindex_index().
  	 *
  	 * If it's a temporary index, we will perform a non-concurrent reindex,
  	 * even if CONCURRENTLY was requested.  In that case, reindex_index() will
  	 * upgrade the lock, but that's OK, because other sessions can't hold
  	 * locks on our temporary table.
  	 */
  	state.options = options;
  	state.locked_table_oid = InvalidOid;
  	indOid = RangeVarGetRelidExtended(indexRelation,
  									  (options & REINDEXOPT_CONCURRENTLY) != 0 ?
  									  ShareUpdateExclusiveLock : AccessExclusiveLock,
  									  0,
  									  RangeVarCallbackForReindexIndex,
  									  &state);
  
  	/*
  	 * Obtain the current persistence and kind of the existing index.  We
  	 * already hold a lock on the index.
  	 */
  	persistence = get_rel_persistence(indOid);
  	relkind = get_rel_relkind(indOid);
  
  	if (relkind == RELKIND_PARTITIONED_INDEX)
  		ReindexPartitions(indOid, options, isTopLevel);
  	else if ((options & REINDEXOPT_CONCURRENTLY) != 0 &&
  			 persistence != RELPERSISTENCE_TEMP)
  		ReindexRelationConcurrently(indOid, options);
  	else
  		reindex_index(indOid, false, persistence,
  					  options | REINDEXOPT_REPORT_PROGRESS);
  }
  
  /*
   * Check permissions on table before acquiring relation lock; also lock
   * the heap before the RangeVarGetRelidExtended takes the index lock, to avoid
   * deadlocks.
   */
  static void
  RangeVarCallbackForReindexIndex(const RangeVar *relation,
  								Oid relId, Oid oldRelId, void *arg)
  {
  	char		relkind;
  	struct ReindexIndexCallbackState *state = arg;
  	LOCKMODE	table_lockmode;
  
  	/*
  	 * Lock level here should match table lock in reindex_index() for
  	 * non-concurrent case and table locks used by index_concurrently_*() for
  	 * concurrent case.
  	 */
  	table_lockmode = ((state->options & REINDEXOPT_CONCURRENTLY) != 0) ?
  		ShareUpdateExclusiveLock : ShareLock;
  
  	/*
  	 * If we previously locked some other index's heap, and the name we're
  	 * looking up no longer refers to that relation, release the now-useless
  	 * lock.
  	 */
  	if (relId != oldRelId && OidIsValid(oldRelId))
  	{
  		UnlockRelationOid(state->locked_table_oid, table_lockmode);
  		state->locked_table_oid = InvalidOid;
  	}
  
  	/* If the relation does not exist, there's nothing more to do. */
  	if (!OidIsValid(relId))
  		return;
  
  	/*
  	 * If the relation does exist, check whether it's an index.  But note that
  	 * the relation might have been dropped between the time we did the name
  	 * lookup and now.  In that case, there's nothing to do.
  	 */
  	relkind = get_rel_relkind(relId);
  	if (!relkind)
  		return;
  	if (relkind != RELKIND_INDEX &&
  		relkind != RELKIND_PARTITIONED_INDEX)
  		ereport(ERROR,
  				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  				 errmsg("\"%s\" is not an index", relation->relname)));
  
  	/* Check permissions */
  	if (!pg_class_ownercheck(relId, GetUserId()))
  		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_INDEX, relation->relname);
  
  	/* Lock heap before index to avoid deadlock. */
  	if (relId != oldRelId)
  	{
  		Oid			table_oid = IndexGetRelation(relId, true);
  
  		/*
  		 * If the OID isn't valid, it means the index was concurrently
  		 * dropped, which is not a problem for us; just return normally.
  		 */
  		if (OidIsValid(table_oid))
  		{
  			LockRelationOid(table_oid, table_lockmode);
  			state->locked_table_oid = table_oid;
  		}
  	}
  }
  
  /*
   * ReindexTable
   *		Recreate all indexes of a table (and of its toast table, if any)
   */
  Oid
  ReindexTable(RangeVar *relation, int options, bool isTopLevel)
  {
  	Oid			heapOid;
  	bool		result;
  
  	/*
  	 * The lock level used here should match reindex_relation().
  	 *
  	 * If it's a temporary table, we will perform a non-concurrent reindex,
  	 * even if CONCURRENTLY was requested.  In that case, reindex_relation()
  	 * will upgrade the lock, but that's OK, because other sessions can't hold
  	 * locks on our temporary table.
  	 */
  	heapOid = RangeVarGetRelidExtended(relation,
  									   (options & REINDEXOPT_CONCURRENTLY) != 0 ?
  									   ShareUpdateExclusiveLock : ShareLock,
  									   0,
  									   RangeVarCallbackOwnsTable, NULL);
  
  	if (get_rel_relkind(heapOid) == RELKIND_PARTITIONED_TABLE)
  		ReindexPartitions(heapOid, options, isTopLevel);
  	else if ((options & REINDEXOPT_CONCURRENTLY) != 0 &&
  			 get_rel_persistence(heapOid) != RELPERSISTENCE_TEMP)
  	{
  		result = ReindexRelationConcurrently(heapOid, options);
  
  		if (!result)
  			ereport(NOTICE,
  					(errmsg("table \"%s\" has no indexes that can be reindexed concurrently",
  							relation->relname)));
  	}
  	else
  	{
  		result = reindex_relation(heapOid,
  								  REINDEX_REL_PROCESS_TOAST |
  								  REINDEX_REL_CHECK_CONSTRAINTS,
  								  options | REINDEXOPT_REPORT_PROGRESS);
  		if (!result)
  			ereport(NOTICE,
  					(errmsg("table \"%s\" has no indexes to reindex",
  							relation->relname)));
  	}
  
  	return heapOid;
  }
  
  /*
   * ReindexMultipleTables
   *		Recreate indexes of tables selected by objectName/objectKind.
   *
   * To reduce the probability of deadlocks, each table is reindexed in a
   * separate transaction, so we can release the lock on it right away.
   * That means this must not be called within a user transaction block!
   */
  void
  ReindexMultipleTables(const char *objectName, ReindexObjectType objectKind,
  					  int options)
  {
  	Oid			objectOid;
  	Relation	relationRelation;
  	TableScanDesc scan;
  	ScanKeyData scan_keys[1];
  	HeapTuple	tuple;
  	MemoryContext private_context;
  	MemoryContext old;
  	List	   *relids = NIL;
  	int			num_keys;
  	bool		concurrent_warning = false;
  
  	AssertArg(objectName);
  	Assert(objectKind == REINDEX_OBJECT_SCHEMA ||
  		   objectKind == REINDEX_OBJECT_SYSTEM ||
  		   objectKind == REINDEX_OBJECT_DATABASE);
  
  	if (objectKind == REINDEX_OBJECT_SYSTEM &&
  		(options & REINDEXOPT_CONCURRENTLY) != 0)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("cannot reindex system catalogs concurrently")));
  
  	/*
  	 * Get OID of object to reindex, being the database currently being used
  	 * by session for a database or for system catalogs, or the schema defined
  	 * by caller. At the same time do permission checks that need different
  	 * processing depending on the object type.
  	 */
  	if (objectKind == REINDEX_OBJECT_SCHEMA)
  	{
  		objectOid = get_namespace_oid(objectName, false);
  
  		if (!pg_namespace_ownercheck(objectOid, GetUserId()))
  			aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SCHEMA,
  						   objectName);
  	}
  	else
  	{
  		objectOid = MyDatabaseId;
  
  		if (strcmp(objectName, get_database_name(objectOid)) != 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("can only reindex the currently open database")));
  		if (!pg_database_ownercheck(objectOid, GetUserId()))
  			aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_DATABASE,
  						   objectName);
  	}
  
  	/*
  	 * Create a memory context that will survive forced transaction commits we
  	 * do below.  Since it is a child of PortalContext, it will go away
  	 * eventually even if we suffer an error; there's no need for special
  	 * abort cleanup logic.
  	 */
  	private_context = AllocSetContextCreate(PortalContext,
  											"ReindexMultipleTables",
  											ALLOCSET_SMALL_SIZES);
  
  	/*
  	 * Define the search keys to find the objects to reindex. For a schema, we
  	 * select target relations using relnamespace, something not necessary for
  	 * a database-wide operation.
  	 */
  	if (objectKind == REINDEX_OBJECT_SCHEMA)
  	{
  		num_keys = 1;
  		ScanKeyInit(&scan_keys[0],
  					Anum_pg_class_relnamespace,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(objectOid));
  	}
  	else
  		num_keys = 0;
  
  	/*
  	 * Scan pg_class to build a list of the relations we need to reindex.
  	 *
  	 * We only consider plain relations and materialized views here (toast
  	 * rels will be processed indirectly by reindex_relation).
  	 */
  	relationRelation = table_open(RelationRelationId, AccessShareLock);
  	scan = table_beginscan_catalog(relationRelation, num_keys, scan_keys);
  	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
  	{
  		Form_pg_class classtuple = (Form_pg_class) GETSTRUCT(tuple);
  		Oid			relid = classtuple->oid;
  
  		/*
  		 * Only regular tables and matviews can have indexes, so ignore any
  		 * other kind of relation.
  		 *
  		 * Partitioned tables/indexes are skipped but matching leaf partitions
  		 * are processed.
  		 */
  		if (classtuple->relkind != RELKIND_RELATION &&
  			classtuple->relkind != RELKIND_MATVIEW)
  			continue;
  
  		/* Skip temp tables of other backends; we can't reindex them at all */
  		if (classtuple->relpersistence == RELPERSISTENCE_TEMP &&
  			!isTempNamespace(classtuple->relnamespace))
  			continue;
  
  		/* Check user/system classification, and optionally skip */
  		if (objectKind == REINDEX_OBJECT_SYSTEM &&
  			!IsSystemClass(relid, classtuple))
  			continue;
  
  		/*
  		 * The table can be reindexed if the user is superuser, the table
  		 * owner, or the database/schema owner (but in the latter case, only
  		 * if it's not a shared relation).  pg_class_ownercheck includes the
  		 * superuser case, and depending on objectKind we already know that
  		 * the user has permission to run REINDEX on this database or schema
  		 * per the permission checks at the beginning of this routine.
  		 */
  		if (classtuple->relisshared &&
  			!pg_class_ownercheck(relid, GetUserId()))
  			continue;
  
  		/*
  		 * Skip system tables, since index_create() would reject indexing them
  		 * concurrently (and it would likely fail if we tried).
  		 */
  		if ((options & REINDEXOPT_CONCURRENTLY) != 0 &&
  			IsCatalogRelationOid(relid))
  		{
  			if (!concurrent_warning)
  				ereport(WARNING,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  						 errmsg("cannot reindex system catalogs concurrently, skipping all")));
  			concurrent_warning = true;
  			continue;
  		}
  
  		/* Save the list of relation OIDs in private context */
  		old = MemoryContextSwitchTo(private_context);
  
  		/*
  		 * We always want to reindex pg_class first if it's selected to be
  		 * reindexed.  This ensures that if there is any corruption in
  		 * pg_class' indexes, they will be fixed before we process any other
  		 * tables.  This is critical because reindexing itself will try to
  		 * update pg_class.
  		 */
  		if (relid == RelationRelationId)
  			relids = lcons_oid(relid, relids);
  		else
  			relids = lappend_oid(relids, relid);
  
  		MemoryContextSwitchTo(old);
  	}
  	table_endscan(scan);
  	table_close(relationRelation, AccessShareLock);
  
  	/*
  	 * Process each relation listed in a separate transaction.  Note that this
  	 * commits and then starts a new transaction immediately.
  	 */
  	ReindexMultipleInternal(relids, options);
  
  	MemoryContextDelete(private_context);
  }
  
  /*
   * Error callback specific to ReindexPartitions().
   */
  static void
  reindex_error_callback(void *arg)
  {
  	ReindexErrorInfo *errinfo = (ReindexErrorInfo *) arg;
  
  	Assert(errinfo->relkind == RELKIND_PARTITIONED_INDEX ||
  		   errinfo->relkind == RELKIND_PARTITIONED_TABLE);
  
  	if (errinfo->relkind == RELKIND_PARTITIONED_TABLE)
  		errcontext("while reindexing partitioned table \"%s.%s\"",
  				   errinfo->relnamespace, errinfo->relname);
  	else if (errinfo->relkind == RELKIND_PARTITIONED_INDEX)
  		errcontext("while reindexing partitioned index \"%s.%s\"",
  				   errinfo->relnamespace, errinfo->relname);
  }
  
  /*
   * ReindexPartitions
   *
   * Reindex a set of partitions, per the partitioned index or table given
   * by the caller.
   */
  static void
  ReindexPartitions(Oid relid, int options, bool isTopLevel)
  {
  	List	   *partitions = NIL;
  	char		relkind = get_rel_relkind(relid);
  	char	   *relname = get_rel_name(relid);
  	char	   *relnamespace = get_namespace_name(get_rel_namespace(relid));
  	MemoryContext reindex_context;
  	List	   *inhoids;
  	ListCell   *lc;
  	ErrorContextCallback errcallback;
  	ReindexErrorInfo errinfo;
  
  	Assert(relkind == RELKIND_PARTITIONED_INDEX ||
  		   relkind == RELKIND_PARTITIONED_TABLE);
  
  	/*
  	 * Check if this runs in a transaction block, with an error callback to
  	 * provide more context under which a problem happens.
  	 */
  	errinfo.relname = pstrdup(relname);
  	errinfo.relnamespace = pstrdup(relnamespace);
  	errinfo.relkind = relkind;
  	errcallback.callback = reindex_error_callback;
  	errcallback.arg = (void *) &errinfo;
  	errcallback.previous = error_context_stack;
  	error_context_stack = &errcallback;
  
  	PreventInTransactionBlock(isTopLevel,
  							  relkind == RELKIND_PARTITIONED_TABLE ?
  							  "REINDEX TABLE" : "REINDEX INDEX");
  
  	/* Pop the error context stack */
  	error_context_stack = errcallback.previous;
  
  	/*
  	 * Create special memory context for cross-transaction storage.
  	 *
  	 * Since it is a child of PortalContext, it will go away eventually even
  	 * if we suffer an error so there is no need for special abort cleanup
  	 * logic.
  	 */
  	reindex_context = AllocSetContextCreate(PortalContext, "Reindex",
  											ALLOCSET_DEFAULT_SIZES);
  
  	/* ShareLock is enough to prevent schema modifications */
  	inhoids = find_all_inheritors(relid, ShareLock, NULL);
  
  	/*
  	 * The list of relations to reindex are the physical partitions of the
  	 * tree so discard any partitioned table or index.
  	 */
  	foreach(lc, inhoids)
  	{
  		Oid			partoid = lfirst_oid(lc);
  		char		partkind = get_rel_relkind(partoid);
  		MemoryContext old_context;
  
  		/*
  		 * This discards partitioned tables, partitioned indexes and foreign
  		 * tables.
  		 */
  		if (!RELKIND_HAS_STORAGE(partkind))
  			continue;
  
  		Assert(partkind == RELKIND_INDEX ||
  			   partkind == RELKIND_RELATION);
  
  		/* Save partition OID */
  		old_context = MemoryContextSwitchTo(reindex_context);
  		partitions = lappend_oid(partitions, partoid);
  		MemoryContextSwitchTo(old_context);
  	}
  
  	/*
  	 * Process each partition listed in a separate transaction.  Note that
  	 * this commits and then starts a new transaction immediately.
  	 */
  	ReindexMultipleInternal(partitions, options);
  
  	/*
  	 * Clean up working storage --- note we must do this after
  	 * StartTransactionCommand, else we might be trying to delete the active
  	 * context!
  	 */
  	MemoryContextDelete(reindex_context);
  }
  
  /*
   * ReindexMultipleInternal
   *
   * Reindex a list of relations, each one being processed in its own
   * transaction.  This commits the existing transaction immediately,
   * and starts a new transaction when finished.
   */
  static void
  ReindexMultipleInternal(List *relids, int options)
  {
  	ListCell   *l;
  
  	PopActiveSnapshot();
  	CommitTransactionCommand();
  
  	foreach(l, relids)
  	{
  		Oid			relid = lfirst_oid(l);
  		char		relkind;
  		char		relpersistence;
  
  		StartTransactionCommand();
  
  		/* functions in indexes may want a snapshot set */
  		PushActiveSnapshot(GetTransactionSnapshot());
  
  		/* check if the relation still exists */
  		if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relid)))
  		{
  			PopActiveSnapshot();
  			CommitTransactionCommand();
  			continue;
  		}
  
  		relkind = get_rel_relkind(relid);
  		relpersistence = get_rel_persistence(relid);
  
  		/*
  		 * Partitioned tables and indexes can never be processed directly, and
  		 * a list of their leaves should be built first.
  		 */
  		Assert(relkind != RELKIND_PARTITIONED_INDEX &&
  			   relkind != RELKIND_PARTITIONED_TABLE);
  
  		if ((options & REINDEXOPT_CONCURRENTLY) != 0 &&
  			relpersistence != RELPERSISTENCE_TEMP)
  		{
  			(void) ReindexRelationConcurrently(relid,
  											   options |
  											   REINDEXOPT_MISSING_OK);
  			/* ReindexRelationConcurrently() does the verbose output */
  		}
  		else if (relkind == RELKIND_INDEX)
  		{
  			reindex_index(relid, false, relpersistence,
  						  options |
  						  REINDEXOPT_REPORT_PROGRESS |
  						  REINDEXOPT_MISSING_OK);
  			PopActiveSnapshot();
  			/* reindex_index() does the verbose output */
  		}
  		else
  		{
  			bool		result;
  
  			result = reindex_relation(relid,
  									  REINDEX_REL_PROCESS_TOAST |
  									  REINDEX_REL_CHECK_CONSTRAINTS,
  									  options |
  									  REINDEXOPT_REPORT_PROGRESS |
  									  REINDEXOPT_MISSING_OK);
  
  			if (result && (options & REINDEXOPT_VERBOSE))
  				ereport(INFO,
  						(errmsg("table \"%s.%s\" was reindexed",
  								get_namespace_name(get_rel_namespace(relid)),
  								get_rel_name(relid))));
  
  			PopActiveSnapshot();
  		}
  
  		CommitTransactionCommand();
  	}
  
  	StartTransactionCommand();
  }
  
  
  /*
   * ReindexRelationConcurrently - process REINDEX CONCURRENTLY for given
   * relation OID
   *
   * 'relationOid' can either belong to an index, a table or a materialized
   * view.  For tables and materialized views, all its indexes will be rebuilt,
   * excluding invalid indexes and any indexes used in exclusion constraints,
   * but including its associated toast table indexes.  For indexes, the index
   * itself will be rebuilt.
   *
   * The locks taken on parent tables and involved indexes are kept until the
   * transaction is committed, at which point a session lock is taken on each
   * relation.  Both of these protect against concurrent schema changes.
   *
   * Returns true if any indexes have been rebuilt (including toast table's
   * indexes, when relevant), otherwise returns false.
   *
   * NOTE: This cannot be used on temporary relations.  A concurrent build would
   * cause issues with ON COMMIT actions triggered by the transactions of the
   * concurrent build.  Temporary relations are not subject to concurrent
   * concerns, so there's no need for the more complicated concurrent build,
   * anyway, and a non-concurrent reindex is more efficient.
   */
  static bool
  ReindexRelationConcurrently(Oid relationOid, int options)
  {
  	List	   *heapRelationIds = NIL;
  	List	   *indexIds = NIL;
  	List	   *newIndexIds = NIL;
  	List	   *relationLocks = NIL;
  	List	   *lockTags = NIL;
  	ListCell   *lc,
  			   *lc2;
  	MemoryContext private_context;
  	MemoryContext oldcontext;
  	char		relkind;
  	char	   *relationName = NULL;
  	char	   *relationNamespace = NULL;
  	PGRUsage	ru0;
  	const int	progress_index[] = {
  		PROGRESS_CREATEIDX_COMMAND,
  		PROGRESS_CREATEIDX_PHASE,
  		PROGRESS_CREATEIDX_INDEX_OID,
  		PROGRESS_CREATEIDX_ACCESS_METHOD_OID
  	};
  	int64		progress_vals[4];
  
  	/*
  	 * Create a memory context that will survive forced transaction commits we
  	 * do below.  Since it is a child of PortalContext, it will go away
  	 * eventually even if we suffer an error; there's no need for special
  	 * abort cleanup logic.
  	 */
  	private_context = AllocSetContextCreate(PortalContext,
  											"ReindexConcurrent",
  											ALLOCSET_SMALL_SIZES);
  
  	if (options & REINDEXOPT_VERBOSE)
  	{
  		/* Save data needed by REINDEX VERBOSE in private context */
  		oldcontext = MemoryContextSwitchTo(private_context);
  
  		relationName = get_rel_name(relationOid);
  		relationNamespace = get_namespace_name(get_rel_namespace(relationOid));
  
  		pg_rusage_init(&ru0);
  
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	relkind = get_rel_relkind(relationOid);
  
  	/*
  	 * Extract the list of indexes that are going to be rebuilt based on the
  	 * relation Oid given by caller.
  	 */
  	switch (relkind)
  	{
  		case RELKIND_RELATION:
  		case RELKIND_MATVIEW:
  		case RELKIND_TOASTVALUE:
  			{
  				/*
  				 * In the case of a relation, find all its indexes including
  				 * toast indexes.
  				 */
  				Relation	heapRelation;
  
  				/* Save the list of relation OIDs in private context */
  				oldcontext = MemoryContextSwitchTo(private_context);
  
  				/* Track this relation for session locks */
  				heapRelationIds = lappend_oid(heapRelationIds, relationOid);
  
  				MemoryContextSwitchTo(oldcontext);
  
  				if (IsCatalogRelationOid(relationOid))
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("cannot reindex system catalogs concurrently")));
  
  				/* Open relation to get its indexes */
  				if ((options & REINDEXOPT_MISSING_OK) != 0)
  				{
  					heapRelation = try_table_open(relationOid,
  												  ShareUpdateExclusiveLock);
  					/* leave if relation does not exist */
  					if (!heapRelation)
  						break;
  				}
  				else
  					heapRelation = table_open(relationOid,
  											  ShareUpdateExclusiveLock);
  
  				/* Add all the valid indexes of relation to list */
  				foreach(lc, RelationGetIndexList(heapRelation))
  				{
  					Oid			cellOid = lfirst_oid(lc);
  					Relation	indexRelation = index_open(cellOid,
  														   ShareUpdateExclusiveLock);
  
  					if (!indexRelation->rd_index->indisvalid)
  						ereport(WARNING,
  								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  								 errmsg("cannot reindex invalid index \"%s.%s\" concurrently, skipping",
  										get_namespace_name(get_rel_namespace(cellOid)),
  										get_rel_name(cellOid))));
  					else if (indexRelation->rd_index->indisexclusion)
  						ereport(WARNING,
  								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  								 errmsg("cannot reindex exclusion constraint index \"%s.%s\" concurrently, skipping",
  										get_namespace_name(get_rel_namespace(cellOid)),
  										get_rel_name(cellOid))));
  					else
  					{
  						/* Save the list of relation OIDs in private context */
  						oldcontext = MemoryContextSwitchTo(private_context);
  
  						indexIds = lappend_oid(indexIds, cellOid);
  
  						MemoryContextSwitchTo(oldcontext);
  					}
  
  					index_close(indexRelation, NoLock);
  				}
  
  				/* Also add the toast indexes */
  				if (OidIsValid(heapRelation->rd_rel->reltoastrelid))
  				{
  					Oid			toastOid = heapRelation->rd_rel->reltoastrelid;
  					Relation	toastRelation = table_open(toastOid,
  														   ShareUpdateExclusiveLock);
  
  					/* Save the list of relation OIDs in private context */
  					oldcontext = MemoryContextSwitchTo(private_context);
  
  					/* Track this relation for session locks */
  					heapRelationIds = lappend_oid(heapRelationIds, toastOid);
  
  					MemoryContextSwitchTo(oldcontext);
  
  					foreach(lc2, RelationGetIndexList(toastRelation))
  					{
  						Oid			cellOid = lfirst_oid(lc2);
  						Relation	indexRelation = index_open(cellOid,
  															   ShareUpdateExclusiveLock);
  
  						if (!indexRelation->rd_index->indisvalid)
  							ereport(WARNING,
  									(errcode(ERRCODE_INDEX_CORRUPTED),
  									 errmsg("cannot reindex invalid index \"%s.%s\" concurrently, skipping",
  											get_namespace_name(get_rel_namespace(cellOid)),
  											get_rel_name(cellOid))));
  						else
  						{
  							/*
  							 * Save the list of relation OIDs in private
  							 * context
  							 */
  							oldcontext = MemoryContextSwitchTo(private_context);
  
  							indexIds = lappend_oid(indexIds, cellOid);
  
  							MemoryContextSwitchTo(oldcontext);
  						}
  
  						index_close(indexRelation, NoLock);
  					}
  
  					table_close(toastRelation, NoLock);
  				}
  
  				table_close(heapRelation, NoLock);
  				break;
  			}
  		case RELKIND_INDEX:
  			{
  				Oid			heapId = IndexGetRelation(relationOid,
  													  (options & REINDEXOPT_MISSING_OK) != 0);
  				Relation	heapRelation;
  
  				/* if relation is missing, leave */
  				if (!OidIsValid(heapId))
  					break;
  
  				if (IsCatalogRelationOid(heapId))
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("cannot reindex system catalogs concurrently")));
  
  				/*
  				 * Don't allow reindex for an invalid index on TOAST table, as
  				 * if rebuilt it would not be possible to drop it.  Match
  				 * error message in reindex_index().
  				 */
  				if (IsToastNamespace(get_rel_namespace(relationOid)) &&
  					!get_index_isvalid(relationOid))
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("cannot reindex invalid index on TOAST table")));
  
  				/*
  				 * Check if parent relation can be locked and if it exists,
  				 * this needs to be done at this stage as the list of indexes
  				 * to rebuild is not complete yet, and REINDEXOPT_MISSING_OK
  				 * should not be used once all the session locks are taken.
  				 */
  				if ((options & REINDEXOPT_MISSING_OK) != 0)
  				{
  					heapRelation = try_table_open(heapId,
  												  ShareUpdateExclusiveLock);
  					/* leave if relation does not exist */
  					if (!heapRelation)
  						break;
  				}
  				else
  					heapRelation = table_open(heapId,
  											  ShareUpdateExclusiveLock);
  				table_close(heapRelation, NoLock);
  
  				/* Save the list of relation OIDs in private context */
  				oldcontext = MemoryContextSwitchTo(private_context);
  
  				/* Track the heap relation of this index for session locks */
  				heapRelationIds = list_make1_oid(heapId);
  
  				/*
  				 * Save the list of relation OIDs in private context.  Note
  				 * that invalid indexes are allowed here.
  				 */
  				indexIds = lappend_oid(indexIds, relationOid);
  
  				MemoryContextSwitchTo(oldcontext);
  				break;
  			}
  
  		case RELKIND_PARTITIONED_TABLE:
  		case RELKIND_PARTITIONED_INDEX:
  		default:
  			/* Return error if type of relation is not supported */
  			ereport(ERROR,
  					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
  					 errmsg("cannot reindex this type of relation concurrently")));
  			break;
  	}
  
  	/*
  	 * Definitely no indexes, so leave.  Any checks based on
  	 * REINDEXOPT_MISSING_OK should be done only while the list of indexes to
  	 * work on is built as the session locks taken before this transaction
  	 * commits will make sure that they cannot be dropped by a concurrent
  	 * session until this operation completes.
  	 */
  	if (indexIds == NIL)
  	{
  		PopActiveSnapshot();
  		return false;
  	}
  
  	Assert(heapRelationIds != NIL);
  
  	/*-----
  	 * Now we have all the indexes we want to process in indexIds.
  	 *
  	 * The phases now are:
  	 *
  	 * 1. create new indexes in the catalog
  	 * 2. build new indexes
  	 * 3. let new indexes catch up with tuples inserted in the meantime
  	 * 4. swap index names
  	 * 5. mark old indexes as dead
  	 * 6. drop old indexes
  	 *
  	 * We process each phase for all indexes before moving to the next phase,
  	 * for efficiency.
  	 */
  
  	/*
  	 * Phase 1 of REINDEX CONCURRENTLY
  	 *
  	 * Create a new index with the same properties as the old one, but it is
  	 * only registered in catalogs and will be built later.  Then get session
  	 * locks on all involved tables.  See analogous code in DefineIndex() for
  	 * more detailed comments.
  	 */
  
  	foreach(lc, indexIds)
  	{
  		char	   *concurrentName;
  		Oid			indexId = lfirst_oid(lc);
  		Oid			newIndexId;
  		Relation	indexRel;
  		Relation	heapRel;
  		Relation	newIndexRel;
  		LockRelId  *lockrelid;
  
  		indexRel = index_open(indexId, ShareUpdateExclusiveLock);
  		heapRel = table_open(indexRel->rd_index->indrelid,
  							 ShareUpdateExclusiveLock);
  
  		/* This function shouldn't be called for temporary relations. */
  		if (indexRel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
  			elog(ERROR, "cannot reindex a temporary table concurrently");
  
  		pgstat_progress_start_command(PROGRESS_COMMAND_CREATE_INDEX,
  									  RelationGetRelid(heapRel));
  		progress_vals[0] = PROGRESS_CREATEIDX_COMMAND_REINDEX_CONCURRENTLY;
  		progress_vals[1] = 0;	/* initializing */
  		progress_vals[2] = indexId;
  		progress_vals[3] = indexRel->rd_rel->relam;
  		pgstat_progress_update_multi_param(4, progress_index, progress_vals);
  
  		/* Choose a temporary relation name for the new index */
  		concurrentName = ChooseRelationName(get_rel_name(indexId),
  											NULL,
  											"ccnew",
  											get_rel_namespace(indexRel->rd_index->indrelid),
  											false);
  
  		/* Create new index definition based on given index */
  		newIndexId = index_concurrently_create_copy(heapRel,
  													indexId,
  													concurrentName);
  
  		/*
  		 * Now open the relation of the new index, a session-level lock is
  		 * also needed on it.
  		 */
  		newIndexRel = index_open(newIndexId, ShareUpdateExclusiveLock);
  
  		/*
  		 * Save the list of OIDs and locks in private context
  		 */
  		oldcontext = MemoryContextSwitchTo(private_context);
  
  		newIndexIds = lappend_oid(newIndexIds, newIndexId);
  
  		/*
  		 * Save lockrelid to protect each relation from drop then close
  		 * relations. The lockrelid on parent relation is not taken here to
  		 * avoid multiple locks taken on the same relation, instead we rely on
  		 * parentRelationIds built earlier.
  		 */
  		lockrelid = palloc(sizeof(*lockrelid));
  		*lockrelid = indexRel->rd_lockInfo.lockRelId;
  		relationLocks = lappend(relationLocks, lockrelid);
  		lockrelid = palloc(sizeof(*lockrelid));
  		*lockrelid = newIndexRel->rd_lockInfo.lockRelId;
  		relationLocks = lappend(relationLocks, lockrelid);
  
  		MemoryContextSwitchTo(oldcontext);
  
  		index_close(indexRel, NoLock);
  		index_close(newIndexRel, NoLock);
  		table_close(heapRel, NoLock);
  	}
  
  	/*
  	 * Save the heap lock for following visibility checks with other backends
  	 * might conflict with this session.
  	 */
  	foreach(lc, heapRelationIds)
  	{
  		Relation	heapRelation = table_open(lfirst_oid(lc), ShareUpdateExclusiveLock);
  		LockRelId  *lockrelid;
  		LOCKTAG    *heaplocktag;
  
  		/* Save the list of locks in private context */
  		oldcontext = MemoryContextSwitchTo(private_context);
  
  		/* Add lockrelid of heap relation to the list of locked relations */
  		lockrelid = palloc(sizeof(*lockrelid));
  		*lockrelid = heapRelation->rd_lockInfo.lockRelId;
  		relationLocks = lappend(relationLocks, lockrelid);
  
  		heaplocktag = (LOCKTAG *) palloc(sizeof(LOCKTAG));
  
  		/* Save the LOCKTAG for this parent relation for the wait phase */
  		SET_LOCKTAG_RELATION(*heaplocktag, lockrelid->dbId, lockrelid->relId);
  		lockTags = lappend(lockTags, heaplocktag);
  
  		MemoryContextSwitchTo(oldcontext);
  
  		/* Close heap relation */
  		table_close(heapRelation, NoLock);
  	}
  
  	/* Get a session-level lock on each table. */
  	foreach(lc, relationLocks)
  	{
  		LockRelId  *lockrelid = (LockRelId *) lfirst(lc);
  
  		LockRelationIdForSession(lockrelid, ShareUpdateExclusiveLock);
  	}
  
  	PopActiveSnapshot();
  	CommitTransactionCommand();
  	StartTransactionCommand();
  
  	/*
  	 * Phase 2 of REINDEX CONCURRENTLY
  	 *
  	 * Build the new indexes in a separate transaction for each index to avoid
  	 * having open transactions for an unnecessary long time.  But before
  	 * doing that, wait until no running transactions could have the table of
  	 * the index open with the old list of indexes.  See "phase 2" in
  	 * DefineIndex() for more details.
  	 */
  
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_1);
  	WaitForLockersMultiple(lockTags, ShareLock, true);
  	CommitTransactionCommand();
  
  	foreach(lc, newIndexIds)
  	{
  		Relation	newIndexRel;
  		Oid			newIndexId = lfirst_oid(lc);
  		Oid			heapId;
  		Oid			indexam;
  
  		/* Start new transaction for this index's concurrent build */
  		StartTransactionCommand();
  
  		/*
  		 * Check for user-requested abort.  This is inside a transaction so as
  		 * xact.c does not issue a useless WARNING, and ensures that
  		 * session-level locks are cleaned up on abort.
  		 */
  		CHECK_FOR_INTERRUPTS();
  
  		/* Set ActiveSnapshot since functions in the indexes may need it */
  		PushActiveSnapshot(GetTransactionSnapshot());
  
  		/*
  		 * Index relation has been closed by previous commit, so reopen it to
  		 * get its information.
  		 */
  		newIndexRel = index_open(newIndexId, ShareUpdateExclusiveLock);
  		heapId = newIndexRel->rd_index->indrelid;
  		indexam = newIndexRel->rd_rel->relam;
  		index_close(newIndexRel, NoLock);
  
  		/*
  		 * Update progress for the index to build, with the correct parent
  		 * table involved.
  		 */
  		pgstat_progress_start_command(PROGRESS_COMMAND_CREATE_INDEX, heapId);
  		progress_vals[0] = PROGRESS_CREATEIDX_COMMAND_REINDEX_CONCURRENTLY;
  		progress_vals[1] = PROGRESS_CREATEIDX_PHASE_BUILD;
  		progress_vals[2] = newIndexId;
  		progress_vals[3] = indexam;
  		pgstat_progress_update_multi_param(4, progress_index, progress_vals);
  
  		/* Perform concurrent build of new index */
  		index_concurrently_build(heapId, newIndexId);
  
  		PopActiveSnapshot();
  		CommitTransactionCommand();
  	}
  	StartTransactionCommand();
  
  	/*
  	 * Phase 3 of REINDEX CONCURRENTLY
  	 *
  	 * During this phase the old indexes catch up with any new tuples that
  	 * were created during the previous phase.  See "phase 3" in DefineIndex()
  	 * for more details.
  	 */
  
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_2);
  	WaitForLockersMultiple(lockTags, ShareLock, true);
  	CommitTransactionCommand();
  
  	foreach(lc, newIndexIds)
  	{
  		Oid			newIndexId = lfirst_oid(lc);
  		Oid			heapId;
  		TransactionId limitXmin;
  		Snapshot	snapshot;
  		Relation	newIndexRel;
  		Oid			indexam;
  
  		StartTransactionCommand();
  
  		/*
  		 * Check for user-requested abort.  This is inside a transaction so as
  		 * xact.c does not issue a useless WARNING, and ensures that
  		 * session-level locks are cleaned up on abort.
  		 */
  		CHECK_FOR_INTERRUPTS();
  
  		/*
  		 * Take the "reference snapshot" that will be used by validate_index()
  		 * to filter candidate tuples.
  		 */
  		snapshot = RegisterSnapshot(GetTransactionSnapshot());
  		PushActiveSnapshot(snapshot);
  
  		/*
  		 * Index relation has been closed by previous commit, so reopen it to
  		 * get its information.
  		 */
  		newIndexRel = index_open(newIndexId, ShareUpdateExclusiveLock);
  		heapId = newIndexRel->rd_index->indrelid;
  		indexam = newIndexRel->rd_rel->relam;
  		index_close(newIndexRel, NoLock);
  
  		/*
  		 * Update progress for the index to build, with the correct parent
  		 * table involved.
  		 */
  		pgstat_progress_start_command(PROGRESS_COMMAND_CREATE_INDEX, heapId);
  		progress_vals[0] = PROGRESS_CREATEIDX_COMMAND_REINDEX_CONCURRENTLY;
  		progress_vals[1] = PROGRESS_CREATEIDX_PHASE_VALIDATE_IDXSCAN;
  		progress_vals[2] = newIndexId;
  		progress_vals[3] = indexam;
  		pgstat_progress_update_multi_param(4, progress_index, progress_vals);
  
  		validate_index(heapId, newIndexId, snapshot);
  
  		/*
  		 * We can now do away with our active snapshot, we still need to save
  		 * the xmin limit to wait for older snapshots.
  		 */
  		limitXmin = snapshot->xmin;
  
  		PopActiveSnapshot();
  		UnregisterSnapshot(snapshot);
  
  		/*
  		 * To ensure no deadlocks, we must commit and start yet another
  		 * transaction, and do our wait before any snapshot has been taken in
  		 * it.
  		 */
  		CommitTransactionCommand();
  		StartTransactionCommand();
  
  		/*
  		 * The index is now valid in the sense that it contains all currently
  		 * interesting tuples.  But since it might not contain tuples deleted
  		 * just before the reference snap was taken, we have to wait out any
  		 * transactions that might have older snapshots.
  		 */
  		pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  									 PROGRESS_CREATEIDX_PHASE_WAIT_3);
  		WaitForOlderSnapshots(limitXmin, true);
  
  		CommitTransactionCommand();
  	}
  
  	/*
  	 * Phase 4 of REINDEX CONCURRENTLY
  	 *
  	 * Now that the new indexes have been validated, swap each new index with
  	 * its corresponding old index.
  	 *
  	 * We mark the new indexes as valid and the old indexes as not valid at
  	 * the same time to make sure we only get constraint violations from the
  	 * indexes with the correct names.
  	 */
  
  	StartTransactionCommand();
  
  	forboth(lc, indexIds, lc2, newIndexIds)
  	{
  		char	   *oldName;
  		Oid			oldIndexId = lfirst_oid(lc);
  		Oid			newIndexId = lfirst_oid(lc2);
  		Oid			heapId;
  
  		/*
  		 * Check for user-requested abort.  This is inside a transaction so as
  		 * xact.c does not issue a useless WARNING, and ensures that
  		 * session-level locks are cleaned up on abort.
  		 */
  		CHECK_FOR_INTERRUPTS();
  
  		heapId = IndexGetRelation(oldIndexId, false);
  
  		/* Choose a relation name for old index */
  		oldName = ChooseRelationName(get_rel_name(oldIndexId),
  									 NULL,
  									 "ccold",
  									 get_rel_namespace(heapId),
  									 false);
  
  		/*
  		 * Swap old index with the new one.  This also marks the new one as
  		 * valid and the old one as not valid.
  		 */
  		index_concurrently_swap(newIndexId, oldIndexId, oldName);
  
  		/*
  		 * Invalidate the relcache for the table, so that after this commit
  		 * all sessions will refresh any cached plans that might reference the
  		 * index.
  		 */
  		CacheInvalidateRelcacheByRelid(heapId);
  
  		/*
  		 * CCI here so that subsequent iterations see the oldName in the
  		 * catalog and can choose a nonconflicting name for their oldName.
  		 * Otherwise, this could lead to conflicts if a table has two indexes
  		 * whose names are equal for the first NAMEDATALEN-minus-a-few
  		 * characters.
  		 */
  		CommandCounterIncrement();
  	}
  
  	/* Commit this transaction and make index swaps visible */
  	CommitTransactionCommand();
  	StartTransactionCommand();
  
  	/*
  	 * Phase 5 of REINDEX CONCURRENTLY
  	 *
  	 * Mark the old indexes as dead.  First we must wait until no running
  	 * transaction could be using the index for a query.  See also
  	 * index_drop() for more details.
  	 */
  
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
  	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
  
  	foreach(lc, indexIds)
  	{
  		Oid			oldIndexId = lfirst_oid(lc);
  		Oid			heapId;
  
  		/*
  		 * Check for user-requested abort.  This is inside a transaction so as
  		 * xact.c does not issue a useless WARNING, and ensures that
  		 * session-level locks are cleaned up on abort.
  		 */
  		CHECK_FOR_INTERRUPTS();
  
  		heapId = IndexGetRelation(oldIndexId, false);
  		index_concurrently_set_dead(heapId, oldIndexId);
  	}
  
  	/* Commit this transaction to make the updates visible. */
  	CommitTransactionCommand();
  	StartTransactionCommand();
  
  	/*
  	 * Phase 6 of REINDEX CONCURRENTLY
  	 *
  	 * Drop the old indexes.
  	 */
  
  	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
  								 PROGRESS_CREATEIDX_PHASE_WAIT_5);
  	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
  
  	PushActiveSnapshot(GetTransactionSnapshot());
  
  	{
  		ObjectAddresses *objects = new_object_addresses();
  
  		foreach(lc, indexIds)
  		{
  			Oid			oldIndexId = lfirst_oid(lc);
  			ObjectAddress object;
  
  			object.classId = RelationRelationId;
  			object.objectId = oldIndexId;
  			object.objectSubId = 0;
  
  			add_exact_object_address(&object, objects);
  		}
  
  		/*
  		 * Use PERFORM_DELETION_CONCURRENT_LOCK so that index_drop() uses the
  		 * right lock level.
  		 */
  		performMultipleDeletions(objects, DROP_RESTRICT,
  								 PERFORM_DELETION_CONCURRENT_LOCK | PERFORM_DELETION_INTERNAL);
  	}
  
  	PopActiveSnapshot();
  	CommitTransactionCommand();
  
  	/*
  	 * Finally, release the session-level lock on the table.
  	 */
  	foreach(lc, relationLocks)
  	{
  		LockRelId  *lockrelid = (LockRelId *) lfirst(lc);
  
  		UnlockRelationIdForSession(lockrelid, ShareUpdateExclusiveLock);
  	}
  
  	/* Start a new transaction to finish process properly */
  	StartTransactionCommand();
  
  	/* Log what we did */
  	if (options & REINDEXOPT_VERBOSE)
  	{
  		if (relkind == RELKIND_INDEX)
  			ereport(INFO,
  					(errmsg("index \"%s.%s\" was reindexed",
  							relationNamespace, relationName),
  					 errdetail("%s.",
  							   pg_rusage_show(&ru0))));
  		else
  		{
  			foreach(lc, newIndexIds)
  			{
  				Oid			indOid = lfirst_oid(lc);
  
  				ereport(INFO,
  						(errmsg("index \"%s.%s\" was reindexed",
  								get_namespace_name(get_rel_namespace(indOid)),
  								get_rel_name(indOid))));
  				/* Don't show rusage here, since it's not per index. */
  			}
  
  			ereport(INFO,
  					(errmsg("table \"%s.%s\" was reindexed",
  							relationNamespace, relationName),
  					 errdetail("%s.",
  							   pg_rusage_show(&ru0))));
  		}
  	}
  
  	MemoryContextDelete(private_context);
  
  	pgstat_progress_end_command();
  
  	return true;
  }
  
  /*
   * Insert or delete an appropriate pg_inherits tuple to make the given index
   * be a partition of the indicated parent index.
   *
   * This also corrects the pg_depend information for the affected index.
   */
  void
  IndexSetParentIndex(Relation partitionIdx, Oid parentOid)
  {
  	Relation	pg_inherits;
  	ScanKeyData key[2];
  	SysScanDesc scan;
  	Oid			partRelid = RelationGetRelid(partitionIdx);
  	HeapTuple	tuple;
  	bool		fix_dependencies;
  
  	/* Make sure this is an index */
  	Assert(partitionIdx->rd_rel->relkind == RELKIND_INDEX ||
  		   partitionIdx->rd_rel->relkind == RELKIND_PARTITIONED_INDEX);
  
  	/*
  	 * Scan pg_inherits for rows linking our index to some parent.
  	 */
  	pg_inherits = relation_open(InheritsRelationId, RowExclusiveLock);
  	ScanKeyInit(&key[0],
  				Anum_pg_inherits_inhrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(partRelid));
  	ScanKeyInit(&key[1],
  				Anum_pg_inherits_inhseqno,
  				BTEqualStrategyNumber, F_INT4EQ,
  				Int32GetDatum(1));
  	scan = systable_beginscan(pg_inherits, InheritsRelidSeqnoIndexId, true,
  							  NULL, 2, key);
  	tuple = systable_getnext(scan);
  
  	if (!HeapTupleIsValid(tuple))
  	{
  		if (parentOid == InvalidOid)
  		{
  			/*
  			 * No pg_inherits row, and no parent wanted: nothing to do in this
  			 * case.
  			 */
  			fix_dependencies = false;
  		}
  		else
  		{
  			Datum		values[Natts_pg_inherits];
  			bool		isnull[Natts_pg_inherits];
  
  			/*
  			 * No pg_inherits row exists, and we want a parent for this index,
  			 * so insert it.
  			 */
  			values[Anum_pg_inherits_inhrelid - 1] = ObjectIdGetDatum(partRelid);
  			values[Anum_pg_inherits_inhparent - 1] =
  				ObjectIdGetDatum(parentOid);
  			values[Anum_pg_inherits_inhseqno - 1] = Int32GetDatum(1);
  			memset(isnull, false, sizeof(isnull));
  
  			tuple = heap_form_tuple(RelationGetDescr(pg_inherits),
  									values, isnull);
  			CatalogTupleInsert(pg_inherits, tuple);
  
  			fix_dependencies = true;
  		}
  	}
  	else
  	{
  		Form_pg_inherits inhForm = (Form_pg_inherits) GETSTRUCT(tuple);
  
  		if (parentOid == InvalidOid)
  		{
  			/*
  			 * There exists a pg_inherits row, which we want to clear; do so.
  			 */
  			CatalogTupleDelete(pg_inherits, &tuple->t_self);
  			fix_dependencies = true;
  		}
  		else
  		{
  			/*
  			 * A pg_inherits row exists.  If it's the same we want, then we're
  			 * good; if it differs, that amounts to a corrupt catalog and
  			 * should not happen.
  			 */
  			if (inhForm->inhparent != parentOid)
  			{
  				/* unexpected: we should not get called in this case */
  				elog(ERROR, "bogus pg_inherit row: inhrelid %u inhparent %u",
  					 inhForm->inhrelid, inhForm->inhparent);
  			}
  
  			/* already in the right state */
  			fix_dependencies = false;
  		}
  	}
  
  	/* done with pg_inherits */
  	systable_endscan(scan);
  	relation_close(pg_inherits, RowExclusiveLock);
  
  	/* set relhassubclass if an index partition has been added to the parent */
  	if (OidIsValid(parentOid))
  		SetRelationHasSubclass(parentOid, true);
  
  	/* set relispartition correctly on the partition */
  	update_relispartition(partRelid, OidIsValid(parentOid));
  
  	if (fix_dependencies)
  	{
  		/*
  		 * Insert/delete pg_depend rows.  If setting a parent, add PARTITION
  		 * dependencies on the parent index and the table; if removing a
  		 * parent, delete PARTITION dependencies.
  		 */
  		if (OidIsValid(parentOid))
  		{
  			ObjectAddress partIdx;
  			ObjectAddress parentIdx;
  			ObjectAddress partitionTbl;
  
  			ObjectAddressSet(partIdx, RelationRelationId, partRelid);
  			ObjectAddressSet(parentIdx, RelationRelationId, parentOid);
  			ObjectAddressSet(partitionTbl, RelationRelationId,
  							 partitionIdx->rd_index->indrelid);
  			recordDependencyOn(&partIdx, &parentIdx,
  							   DEPENDENCY_PARTITION_PRI);
  			recordDependencyOn(&partIdx, &partitionTbl,
  							   DEPENDENCY_PARTITION_SEC);
  		}
  		else
  		{
  			deleteDependencyRecordsForClass(RelationRelationId, partRelid,
  											RelationRelationId,
  											DEPENDENCY_PARTITION_PRI);
  			deleteDependencyRecordsForClass(RelationRelationId, partRelid,
  											RelationRelationId,
  											DEPENDENCY_PARTITION_SEC);
  		}
  
  		/* make our updates visible */
  		CommandCounterIncrement();
  	}
  }
  
  /*
   * Subroutine of IndexSetParentIndex to update the relispartition flag of the
   * given index to the given value.
   */
  static void
  update_relispartition(Oid relationId, bool newval)
  {
  	HeapTuple	tup;
  	Relation	classRel;
  
  	classRel = table_open(RelationRelationId, RowExclusiveLock);
  	tup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relationId));
  	if (!HeapTupleIsValid(tup))
  		elog(ERROR, "cache lookup failed for relation %u", relationId);
  	Assert(((Form_pg_class) GETSTRUCT(tup))->relispartition != newval);
  	((Form_pg_class) GETSTRUCT(tup))->relispartition = newval;
  	CatalogTupleUpdate(classRel, &tup->t_self, tup);
  	heap_freetuple(tup);
  	table_close(classRel, RowExclusiveLock);
  }
  