text: /*-------------------------------------------------------------------------
   *
   * index.c
   *	  code to create and destroy POSTGRES index relations
   *
   * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/catalog/index.c
   *
   *
   * INTERFACE ROUTINES
   *		index_create()			- Create a cataloged index relation
   *		index_drop()			- Removes index relation from catalogs
   *		BuildIndexInfo()		- Prepare to insert index tuples
   *		FormIndexDatum()		- Construct datum vector for one index tuple
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include <unistd.h>
  
  #include "access/amapi.h"
  #include "access/multixact.h"
  #include "access/relscan.h"
  #include "access/reloptions.h"
  #include "access/sysattr.h"
  #include "access/transam.h"
  #include "access/visibilitymap.h"
  #include "access/xact.h"
  #include "bootstrap/bootstrap.h"
  #include "catalog/binary_upgrade.h"
  #include "catalog/catalog.h"
  #include "catalog/dependency.h"
  #include "catalog/heap.h"
  #include "catalog/index.h"
  #include "catalog/objectaccess.h"
  #include "catalog/pg_am.h"
  #include "catalog/pg_collation.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_depend.h"
  #include "catalog/pg_inherits.h"
  #include "catalog/pg_operator.h"
  #include "catalog/pg_opclass.h"
  #include "catalog/pg_tablespace.h"
  #include "catalog/pg_trigger.h"
  #include "catalog/pg_type.h"
  #include "catalog/storage.h"
  #include "commands/tablecmds.h"
  #include "commands/event_trigger.h"
  #include "commands/trigger.h"
  #include "executor/executor.h"
  #include "miscadmin.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/clauses.h"
  #include "optimizer/planner.h"
  #include "parser/parser.h"
  #include "rewrite/rewriteManip.h"
  #include "storage/bufmgr.h"
  #include "storage/lmgr.h"
  #include "storage/predicate.h"
  #include "storage/procarray.h"
  #include "storage/smgr.h"
  #include "utils/builtins.h"
  #include "utils/fmgroids.h"
  #include "utils/guc.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/pg_rusage.h"
  #include "utils/syscache.h"
  #include "utils/tuplesort.h"
  #include "utils/snapmgr.h"
  #include "utils/tqual.h"
  
  /*  YB includes. */
  #include "commands/ybccmds.h"
  #include "pg_yb_utils.h"
  
  /* Potentially set by pg_upgrade_support functions */
  Oid			binary_upgrade_next_index_pg_class_oid = InvalidOid;
  
  /* state info for validate_index bulkdelete callback */
  typedef struct
  {
  	Tuplesortstate *tuplesort;	/* for sorting the index TIDs */
  	/* statistics (for debug purposes only): */
  	double		htups,
  				itups,
  				tups_inserted;
  } v_i_state;
  
  /*
   * Pointer-free representation of variables used when reindexing system
   * catalogs; we use this to propagate those values to parallel workers.
   */
  typedef struct
  {
  	Oid			currentlyReindexedHeap;
  	Oid			currentlyReindexedIndex;
  	int			numPendingReindexedIndexes;
  	Oid			pendingReindexedIndexes[FLEXIBLE_ARRAY_MEMBER];
  } SerializedReindexState;
  
  /* non-export function prototypes */
  static bool relationHasPrimaryKey(Relation rel);
  static TupleDesc ConstructTupleDescriptor(Relation heapRelation,
  						 IndexInfo *indexInfo,
  						 List *indexColNames,
  						 Oid accessMethodObjectId,
  						 Oid *collationObjectId,
  						 Oid *classObjectId);
  static void InitializeAttributeOids(Relation indexRelation,
  						int numatts, Oid indexoid);
  static void AppendAttributeTuples(Relation indexRelation, int numatts);
  static void UpdateIndexRelation(Oid indexoid, Oid heapoid,
  					Oid parentIndexId,
  					IndexInfo *indexInfo,
  					Oid *collationOids,
  					Oid *classOids,
  					int16 *coloptions,
  					bool primary,
  					bool isexclusion,
  					bool immediate,
  					bool isvalid,
  					bool isready);
  static void index_update_stats(Relation rel,
  				   bool hasindex,
  				   double reltuples);
  static double IndexBuildHeapRangeScanInternal(Relation heapRelation,
  											  Relation indexRelation,
  											  IndexInfo *indexInfo,
  											  bool allow_sync,
  											  bool anyvisible,
  											  BlockNumber start_blockno,
  											  BlockNumber numblocks,
  											  IndexBuildCallback callback,
  											  void *callback_state,
  											  HeapScanDesc scan,
  											  uint64_t *read_time,
  											  RowBounds *row_bounds);
  static void IndexCheckExclusion(Relation heapRelation,
  					Relation indexRelation,
  					IndexInfo *indexInfo);
  static inline int64 itemptr_encode(ItemPointer itemptr);
  static inline void itemptr_decode(ItemPointer itemptr, int64 encoded);
  static bool validate_index_callback(ItemPointer itemptr, void *opaque);
  static void validate_index_heapscan(Relation heapRelation,
  						Relation indexRelation,
  						IndexInfo *indexInfo,
  						Snapshot snapshot,
  						v_i_state *state);
  static bool ReindexIsCurrentlyProcessingIndex(Oid indexOid);
  static void SetReindexProcessing(Oid heapOid, Oid indexOid);
  static void ResetReindexProcessing(void);
  static void SetReindexPending(List *indexes);
  static void RemoveReindexPending(Oid indexOid);
  static void ResetReindexPending(void);
  
  
  /*
   * relationHasPrimaryKey
   *		See whether an existing relation has a primary key.
   *
   * Caller must have suitable lock on the relation.
   *
   * Note: we intentionally do not check IndexIsValid here; that's because this
   * is used to enforce the rule that there can be only one indisprimary index,
   * and we want that to be true even if said index is invalid.
   */
  static bool
  relationHasPrimaryKey(Relation rel)
  {
  	bool		result = false;
  	List	   *indexoidlist;
  	ListCell   *indexoidscan;
  
  	/*
  	 * Get the list of index OIDs for the table from the relcache, and look up
  	 * each one in the pg_index syscache until we find one marked primary key
  	 * (hopefully there isn't more than one such).
  	 */
  	indexoidlist = RelationGetIndexList(rel);
  
  	foreach(indexoidscan, indexoidlist)
  	{
  		Oid			indexoid = lfirst_oid(indexoidscan);
  		HeapTuple	indexTuple;
  
  		indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
  		if (!HeapTupleIsValid(indexTuple))	/* should not happen */
  			elog(ERROR, "cache lookup failed for index %u", indexoid);
  		result = ((Form_pg_index) GETSTRUCT(indexTuple))->indisprimary;
  		ReleaseSysCache(indexTuple);
  		if (result)
  			break;
  	}
  
  	list_free(indexoidlist);
  
  	return result;
  }
  
  /*
   * index_check_primary_key
   *		Apply special checks needed before creating a PRIMARY KEY index
   *
   * This processing used to be in DefineIndex(), but has been split out
   * so that it can be applied during ALTER TABLE ADD PRIMARY KEY USING INDEX.
   *
   * We check for a pre-existing primary key, and that all columns of the index
   * are simple column references (not expressions), and that all those
   * columns are marked NOT NULL.  If they aren't (which can only happen during
   * ALTER TABLE ADD CONSTRAINT, since the parser forces such columns to be
   * created NOT NULL during CREATE TABLE), do an ALTER SET NOT NULL to mark
   * them so --- or fail if they are not in fact nonnull.
   *
   * As of PG v10, the SET NOT NULL is applied to child tables as well, so
   * that the behavior is like a manual SET NOT NULL.
   *
   * Caller had better have at least ShareLock on the table, else the not-null
   * checking isn't trustworthy.
   */
  void
  index_check_primary_key(Relation heapRel,
  						IndexInfo *indexInfo,
  						bool is_alter_table,
  						IndexStmt *stmt)
  {
  	List	   *cmds;
  	int			i;
  
  	/*
  	 * If ALTER TABLE and CREATE TABLE .. PARTITION OF, check that there isn't
  	 * already a PRIMARY KEY.  In CREATE TABLE for an ordinary relations, we
  	 * have faith that the parser rejected multiple pkey clauses; and CREATE
  	 * INDEX doesn't have a way to say PRIMARY KEY, so it's no problem either.
  	 */
  	if ((is_alter_table || heapRel->rd_rel->relispartition) &&
  		relationHasPrimaryKey(heapRel))
  	{
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  				 errmsg("multiple primary keys for table \"%s\" are not allowed",
  						RelationGetRelationName(heapRel))));
  	}
  
  	/*
  	 * Check that all of the attributes in a primary key are marked as not
  	 * null, otherwise attempt to ALTER TABLE .. SET NOT NULL
  	 */
  	cmds = NIL;
  	for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
  	{
  		AttrNumber	attnum = indexInfo->ii_IndexAttrNumbers[i];
  		HeapTuple	atttuple;
  		Form_pg_attribute attform;
  
  		if (attnum == 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("primary keys cannot be expressions")));
  
  		/* System attributes are never null, so no need to check */
  		if (attnum < 0)
  			continue;
  
  		atttuple = SearchSysCache2(ATTNUM,
  								   ObjectIdGetDatum(RelationGetRelid(heapRel)),
  								   Int16GetDatum(attnum));
  		if (!HeapTupleIsValid(atttuple))
  			elog(ERROR, "cache lookup failed for attribute %d of relation %u",
  				 attnum, RelationGetRelid(heapRel));
  		attform = (Form_pg_attribute) GETSTRUCT(atttuple);
  
  		if (!attform->attnotnull)
  		{
  			/* Add a subcommand to make this one NOT NULL */
  			AlterTableCmd *cmd = makeNode(AlterTableCmd);
  
  			cmd->subtype = AT_SetNotNull;
  			cmd->name = pstrdup(NameStr(attform->attname));
  			cmds = lappend(cmds, cmd);
  		}
  
  		ReleaseSysCache(atttuple);
  	}
  
  	/*
  	 * XXX: possible future improvement: when being called from ALTER TABLE,
  	 * it would be more efficient to merge this with the outer ALTER TABLE, so
  	 * as to avoid two scans.  But that seems to complicate DefineIndex's API
  	 * unduly.
  	 */
  	if (cmds)
  	{
  		EventTriggerAlterTableStart((Node *) stmt);
  		AlterTableInternal(RelationGetRelid(heapRel), cmds, true);
  		EventTriggerAlterTableEnd();
  	}
  }
  
  /*
   *		ConstructTupleDescriptor
   *
   * Build an index tuple descriptor for a new index
   */
  static TupleDesc
  ConstructTupleDescriptor(Relation heapRelation,
  						 IndexInfo *indexInfo,
  						 List *indexColNames,
  						 Oid accessMethodObjectId,
  						 Oid *collationObjectId,
  						 Oid *classObjectId)
  {
  	int			numatts = indexInfo->ii_NumIndexAttrs;
  	int			numkeyatts = indexInfo->ii_NumIndexKeyAttrs;
  	ListCell   *colnames_item = list_head(indexColNames);
  	ListCell   *indexpr_item = list_head(indexInfo->ii_Expressions);
  	IndexAmRoutine *amroutine;
  	TupleDesc	heapTupDesc;
  	TupleDesc	indexTupDesc;
  	int			natts;			/* #atts in heap rel --- for error checks */
  	int			i;
  
  	/* We need access to the index AM's API struct */
  	amroutine = GetIndexAmRoutineByAmId(accessMethodObjectId, false);
  
  	/* ... and to the table's tuple descriptor */
  	heapTupDesc = RelationGetDescr(heapRelation);
  	natts = RelationGetForm(heapRelation)->relnatts;
  
  	/*
  	 * allocate the new tuple descriptor
  	 */
  	indexTupDesc = CreateTemplateTupleDesc(numatts, false);
  
  	/*
  	 * For simple index columns, we copy the pg_attribute row from the parent
  	 * relation and modify it as necessary.  For expressions we have to cons
  	 * up a pg_attribute row the hard way.
  	 */
  	for (i = 0; i < numatts; i++)
  	{
  		AttrNumber	atnum = indexInfo->ii_IndexAttrNumbers[i];
  		Form_pg_attribute to = TupleDescAttr(indexTupDesc, i);
  		HeapTuple	tuple;
  		Form_pg_type typeTup;
  		Form_pg_opclass opclassTup;
  		Oid			keyType;
  
  		if (atnum != 0)
  		{
  			/* Simple index column */
  			Form_pg_attribute from;
  
  			if (atnum < 0)
  			{
  				/*
  				 * here we are indexing on a system attribute (-1...-n)
  				 */
  				from = SystemAttributeDefinition(atnum,
  												 heapRelation->rd_rel->relhasoids);
  			}
  			else
  			{
  				/*
  				 * here we are indexing on a normal attribute (1...n)
  				 */
  				if (atnum > natts)	/* safety check */
  					elog(ERROR, "invalid column number %d", atnum);
  				from = TupleDescAttr(heapTupDesc,
  									 AttrNumberGetAttrOffset(atnum));
  			}
  
  			/*
  			 * now that we've determined the "from", let's copy the tuple desc
  			 * data...
  			 */
  			memcpy(to, from, ATTRIBUTE_FIXED_PART_SIZE);
  
  			/*
  			 * Fix the stuff that should not be the same as the underlying
  			 * attr
  			 */
  			to->attnum = i + 1;
  
  			to->attstattarget = -1;
  			to->attcacheoff = -1;
  			to->attnotnull = false;
  			to->atthasdef = false;
  			to->atthasmissing = false;
  			to->attidentity = '\0';
  			to->attislocal = true;
  			to->attinhcount = 0;
  			to->attcollation = (i < numkeyatts) ?
  				collationObjectId[i] : InvalidOid;
  		}
  		else
  		{
  			/* Expressional index */
  			Node	   *indexkey;
  
  			MemSet(to, 0, ATTRIBUTE_FIXED_PART_SIZE);
  
  			if (indexpr_item == NULL)	/* shouldn't happen */
  				elog(ERROR, "too few entries in indexprs list");
  			indexkey = (Node *) lfirst(indexpr_item);
  			indexpr_item = lnext(indexpr_item);
  
  			/*
  			 * Lookup the expression type in pg_type for the type length etc.
  			 */
  			keyType = exprType(indexkey);
  			tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(keyType));
  			if (!HeapTupleIsValid(tuple))
  				elog(ERROR, "cache lookup failed for type %u", keyType);
  			typeTup = (Form_pg_type) GETSTRUCT(tuple);
  
  			/*
  			 * Assign some of the attributes values. Leave the rest as 0.
  			 */
  			to->attnum = i + 1;
  			to->atttypid = keyType;
  			to->attlen = typeTup->typlen;
  			to->attbyval = typeTup->typbyval;
  			to->attstorage = typeTup->typstorage;
  			to->attalign = typeTup->typalign;
  			to->attstattarget = -1;
  			to->attcacheoff = -1;
  			to->atttypmod = exprTypmod(indexkey);
  			to->attislocal = true;
  			to->attcollation = (i < numkeyatts) ?
  				collationObjectId[i] : InvalidOid;
  
  			ReleaseSysCache(tuple);
  
  			/*
  			 * Make sure the expression yields a type that's safe to store in
  			 * an index.  We need this defense because we have index opclasses
  			 * for pseudo-types such as "record", and the actually stored type
  			 * had better be safe; eg, a named composite type is okay, an
  			 * anonymous record type is not.  The test is the same as for
  			 * whether a table column is of a safe type (which is why we
  			 * needn't check for the non-expression case).
  			 */
  			CheckAttributeType(NameStr(to->attname),
  							   to->atttypid, to->attcollation,
  							   NIL, false);
  		}
  
  		/*
  		 * We do not yet have the correct relation OID for the index, so just
  		 * set it invalid for now.  InitializeAttributeOids() will fix it
  		 * later.
  		 */
  		to->attrelid = InvalidOid;
  
  		/*
  		 * Set the attribute name as specified by caller.
  		 */
  		if (colnames_item == NULL)	/* shouldn't happen */
  			elog(ERROR, "too few entries in colnames list");
  		namestrcpy(&to->attname, (const char *) lfirst(colnames_item));
  		colnames_item = lnext(colnames_item);
  
  		/*
  		 * Check the opclass and index AM to see if either provides a keytype
  		 * (overriding the attribute type).  Opclass (if exists) takes
  		 * precedence.
  		 */
  		keyType = amroutine->amkeytype;
  
  		/*
  		 * Code below is concerned to the opclasses which are not used with
  		 * the included columns.
  		 */
  		if (i < indexInfo->ii_NumIndexKeyAttrs)
  		{
  			tuple = SearchSysCache1(CLAOID, ObjectIdGetDatum(classObjectId[i]));
  			if (!HeapTupleIsValid(tuple))
  				elog(ERROR, "cache lookup failed for opclass %u",
  					 classObjectId[i]);
  			opclassTup = (Form_pg_opclass) GETSTRUCT(tuple);
  			if (OidIsValid(opclassTup->opckeytype))
  				keyType = opclassTup->opckeytype;
  
  			/*
  			 * If keytype is specified as ANYELEMENT, and opcintype is
  			 * ANYARRAY, then the attribute type must be an array (else it'd
  			 * not have matched this opclass); use its element type.
  			 */
  			if (keyType == ANYELEMENTOID && opclassTup->opcintype == ANYARRAYOID)
  			{
  				keyType = get_base_element_type(to->atttypid);
  				if (!OidIsValid(keyType))
  					elog(ERROR, "could not get element type of array type %u",
  						 to->atttypid);
  			}
  
  			ReleaseSysCache(tuple);
  		}
  
  		/*
  		 * If a key type different from the heap value is specified, update
  		 * the type-related fields in the index tupdesc.
  		 */
  		if (OidIsValid(keyType) && keyType != to->atttypid)
  		{
  			tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(keyType));
  			if (!HeapTupleIsValid(tuple))
  				elog(ERROR, "cache lookup failed for type %u", keyType);
  			typeTup = (Form_pg_type) GETSTRUCT(tuple);
  
  			to->atttypid = keyType;
  			to->atttypmod = -1;
  			to->attlen = typeTup->typlen;
  			to->attbyval = typeTup->typbyval;
  			to->attalign = typeTup->typalign;
  			to->attstorage = typeTup->typstorage;
  
  			ReleaseSysCache(tuple);
  		}
  	}
  
  	pfree(amroutine);
  
  	return indexTupDesc;
  }
  
  /* ----------------------------------------------------------------
   *		InitializeAttributeOids
   * ----------------------------------------------------------------
   */
  static void
  InitializeAttributeOids(Relation indexRelation,
  						int numatts,
  						Oid indexoid)
  {
  	TupleDesc	tupleDescriptor;
  	int			i;
  
  	tupleDescriptor = RelationGetDescr(indexRelation);
  
  	for (i = 0; i < numatts; i += 1)
  		TupleDescAttr(tupleDescriptor, i)->attrelid = indexoid;
  }
  
  /* ----------------------------------------------------------------
   *		AppendAttributeTuples
   * ----------------------------------------------------------------
   */
  static void
  AppendAttributeTuples(Relation indexRelation, int numatts)
  {
  	Relation	pg_attribute;
  	CatalogIndexState indstate;
  	TupleDesc	indexTupDesc;
  	int			i;
  
  	/*
  	 * open the attribute relation and its indexes
  	 */
  	pg_attribute = heap_open(AttributeRelationId, RowExclusiveLock);
  
  	indstate = CatalogOpenIndexes(pg_attribute);
  
  	/*
  	 * insert data from new index's tupdesc into pg_attribute
  	 */
  	indexTupDesc = RelationGetDescr(indexRelation);
  
  	for (i = 0; i < numatts; i++)
  	{
  		Form_pg_attribute attr = TupleDescAttr(indexTupDesc, i);
  
  		/*
  		 * There used to be very grotty code here to set these fields, but I
  		 * think it's unnecessary.  They should be set already.
  		 */
  		Assert(attr->attnum == i + 1);
  		Assert(attr->attcacheoff == -1);
  
  		InsertPgAttributeTuple(pg_attribute, attr, indstate);
  	}
  
  	CatalogCloseIndexes(indstate);
  
  	heap_close(pg_attribute, RowExclusiveLock);
  }
  
  /* ----------------------------------------------------------------
   *		UpdateIndexRelation
   *
   * Construct and insert a new entry in the pg_index catalog
   * ----------------------------------------------------------------
   */
  static void
  UpdateIndexRelation(Oid indexoid,
  					Oid heapoid,
  					Oid parentIndexOid,
  					IndexInfo *indexInfo,
  					Oid *collationOids,
  					Oid *classOids,
  					int16 *coloptions,
  					bool primary,
  					bool isexclusion,
  					bool immediate,
  					bool isvalid,
  					bool isready)
  {
  	int2vector *indkey;
  	oidvector  *indcollation;
  	oidvector  *indclass;
  	int2vector *indoption;
  	Datum		exprsDatum;
  	Datum		predDatum;
  	Datum		values[Natts_pg_index];
  	bool		nulls[Natts_pg_index];
  	Relation	pg_index;
  	HeapTuple	tuple;
  	int			i;
  
  	/*
  	 * Copy the index key, opclass, and indoption info into arrays (should we
  	 * make the caller pass them like this to start with?)
  	 */
  	indkey = buildint2vector(NULL, indexInfo->ii_NumIndexAttrs);
  	for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
  		indkey->values[i] = indexInfo->ii_IndexAttrNumbers[i];
  	indcollation = buildoidvector(collationOids, indexInfo->ii_NumIndexKeyAttrs);
  	indclass = buildoidvector(classOids, indexInfo->ii_NumIndexKeyAttrs);
  	indoption = buildint2vector(coloptions, indexInfo->ii_NumIndexKeyAttrs);
  
  	/*
  	 * Convert the index expressions (if any) to a text datum
  	 */
  	if (indexInfo->ii_Expressions != NIL)
  	{
  		char	   *exprsString;
  
  		exprsString = nodeToString(indexInfo->ii_Expressions);
  		exprsDatum = CStringGetTextDatum(exprsString);
  		pfree(exprsString);
  	}
  	else
  		exprsDatum = (Datum) 0;
  
  	/*
  	 * Convert the index predicate (if any) to a text datum.  Note we convert
  	 * implicit-AND format to normal explicit-AND for storage.
  	 */
  	if (indexInfo->ii_Predicate != NIL)
  	{
  		char	   *predString;
  
  		predString = nodeToString(make_ands_explicit(indexInfo->ii_Predicate));
  		predDatum = CStringGetTextDatum(predString);
  		pfree(predString);
  	}
  	else
  		predDatum = (Datum) 0;
  
  	/*
  	 * open the system catalog index relation
  	 */
  	pg_index = heap_open(IndexRelationId, RowExclusiveLock);
  
  	/*
  	 * Build a pg_index tuple
  	 */
  	MemSet(nulls, false, sizeof(nulls));
  
  	values[Anum_pg_index_indexrelid - 1] = ObjectIdGetDatum(indexoid);
  	values[Anum_pg_index_indrelid - 1] = ObjectIdGetDatum(heapoid);
  	values[Anum_pg_index_indnatts - 1] = Int16GetDatum(indexInfo->ii_NumIndexAttrs);
  	values[Anum_pg_index_indnkeyatts - 1] = Int16GetDatum(indexInfo->ii_NumIndexKeyAttrs);
  	values[Anum_pg_index_indisunique - 1] = BoolGetDatum(indexInfo->ii_Unique);
  	values[Anum_pg_index_indisprimary - 1] = BoolGetDatum(primary);
  	values[Anum_pg_index_indisexclusion - 1] = BoolGetDatum(isexclusion);
  	values[Anum_pg_index_indimmediate - 1] = BoolGetDatum(immediate);
  	values[Anum_pg_index_indisclustered - 1] = BoolGetDatum(false);
  	values[Anum_pg_index_indisvalid - 1] = BoolGetDatum(isvalid);
  	values[Anum_pg_index_indcheckxmin - 1] = BoolGetDatum(false);
  	values[Anum_pg_index_indisready - 1] = BoolGetDatum(isready);
  	values[Anum_pg_index_indislive - 1] = BoolGetDatum(true);
  	values[Anum_pg_index_indisreplident - 1] = BoolGetDatum(false);
  	values[Anum_pg_index_indkey - 1] = PointerGetDatum(indkey);
  	values[Anum_pg_index_indcollation - 1] = PointerGetDatum(indcollation);
  	values[Anum_pg_index_indclass - 1] = PointerGetDatum(indclass);
  	values[Anum_pg_index_indoption - 1] = PointerGetDatum(indoption);
  	values[Anum_pg_index_indexprs - 1] = exprsDatum;
  	if (exprsDatum == (Datum) 0)
  		nulls[Anum_pg_index_indexprs - 1] = true;
  	values[Anum_pg_index_indpred - 1] = predDatum;
  	if (predDatum == (Datum) 0)
  		nulls[Anum_pg_index_indpred - 1] = true;
  
  	tuple = heap_form_tuple(RelationGetDescr(pg_index), values, nulls);
  
  	/*
  	 * insert the tuple into the pg_index catalog
  	 */
  	CatalogTupleInsert(pg_index, tuple);
  
  	/*
  	 * close the relation and free the tuple
  	 */
  	heap_close(pg_index, RowExclusiveLock);
  	heap_freetuple(tuple);
  }
  
  
  /*
   * index_create
   *
   * heapRelation: table to build index on (suitably locked by caller)
   * indexRelationName: what it say
   * indexRelationId: normally, pass InvalidOid to let this routine
   *		generate an OID for the index.  During bootstrap this may be
   *		nonzero to specify a preselected OID.
   * parentIndexRelid: if creating an index partition, the OID of the
   *		parent index; otherwise InvalidOid.
   * parentConstraintId: if creating a constraint on a partition, the OID
   *		of the constraint in the parent; otherwise InvalidOid.
   * relFileNode: normally, pass InvalidOid to get new storage.  May be
   *		nonzero to attach an existing valid build.
   * indexInfo: same info executor uses to insert into the index
   * indexColNames: column names to use for index (List of char *)
   * accessMethodObjectId: OID of index AM to use
   * tableSpaceId: OID of tablespace to use
   * collationObjectId: array of collation OIDs, one per index column
   * classObjectId: array of index opclass OIDs, one per index column
   * coloptions: array of per-index-column indoption settings
   * reloptions: AM-specific options
   * flags: bitmask that can include any combination of these bits:
   *		INDEX_CREATE_IS_PRIMARY
   *			the index is a primary key
   *		INDEX_CREATE_ADD_CONSTRAINT:
   *			invoke index_constraint_create also
   *		INDEX_CREATE_SKIP_BUILD:
   *			skip the index_build() step for the moment; caller must do it
   *			later (typically via reindex_index())
   *		INDEX_CREATE_CONCURRENT:
   *			do not lock the table against writers.  The index will be
   *			marked "invalid" and the caller must take additional steps
   *			to fix it up.
   *		INDEX_CREATE_IF_NOT_EXISTS:
   *			do not throw an error if a relation with the same name
   *			already exists.
   *		INDEX_CREATE_PARTITIONED:
   *			create a partitioned index (table must be partitioned)
   * constr_flags: flags passed to index_constraint_create
   *		(only if INDEX_CREATE_ADD_CONSTRAINT is set)
   * allow_system_table_mods: allow table to be a system catalog
   * is_internal: if true, post creation hook for new index
   * constraintId: if not NULL, receives OID of created constraint
   *
   * Returns the OID of the created index.
   */
  Oid
  index_create(Relation heapRelation,
  			 const char *indexRelationName,
  			 Oid indexRelationId,
  			 Oid parentIndexRelid,
  			 Oid parentConstraintId,
  			 Oid relFileNode,
  			 IndexInfo *indexInfo,
  			 List *indexColNames,
  			 Oid accessMethodObjectId,
  			 Oid tableSpaceId,
  			 Oid *collationObjectId,
  			 Oid *classObjectId,
  			 int16 *coloptions,
  			 Datum reloptions,
  			 bits16 flags,
  			 bits16 constr_flags,
  			 bool allow_system_table_mods,
  			 bool is_internal,
  			 Oid *constraintId,
  			 OptSplit *split_options,
  			 const bool skip_index_backfill,
  			 Oid tablegroupId)
  {
  	Oid			heapRelationId = RelationGetRelid(heapRelation);
  	Relation	pg_class;
  	Relation	indexRelation;
  	TupleDesc	indexTupDesc;
  	bool		shared_relation;
  	bool		mapped_relation;
  	bool		is_exclusion;
  	Oid			namespaceId;
  	int			i;
  	char		relpersistence;
  	bool		isprimary = (flags & INDEX_CREATE_IS_PRIMARY) != 0;
  	bool		invalid = (flags & INDEX_CREATE_INVALID) != 0;
  	bool		concurrent = (flags & INDEX_CREATE_CONCURRENT) != 0;
  	bool		partitioned = (flags & INDEX_CREATE_PARTITIONED) != 0;
  	char		relkind;
  
  	/* constraint flags can only be set when a constraint is requested */
  	Assert((constr_flags == 0) ||
  		   ((flags & INDEX_CREATE_ADD_CONSTRAINT) != 0));
  	/* partitioned indexes must never be "built" by themselves */
  	Assert(!partitioned || (flags & INDEX_CREATE_SKIP_BUILD));
  
  	relkind = partitioned ? RELKIND_PARTITIONED_INDEX : RELKIND_INDEX;
  	is_exclusion = (indexInfo->ii_ExclusionOps != NULL);
  
  	pg_class = heap_open(RelationRelationId, RowExclusiveLock);
  
  	/*
  	 * The index will be in the same namespace as its parent table, and is
  	 * shared across databases if and only if the parent is.  Likewise, it
  	 * will use the relfilenode map if and only if the parent does; and it
  	 * inherits the parent's relpersistence.
  	 */
  	namespaceId = RelationGetNamespace(heapRelation);
  	shared_relation = heapRelation->rd_rel->relisshared;
  	mapped_relation = RelationIsMapped(heapRelation);
  	relpersistence = heapRelation->rd_rel->relpersistence;
  
  	/*
  	 * check parameters
  	 */
  	if (indexInfo->ii_NumIndexAttrs < 1)
  		elog(ERROR, "must index at least one column");
  
  	if (!allow_system_table_mods &&
  		IsSystemRelation(heapRelation) &&
  		IsNormalProcessingMode())
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("user-defined indexes on system catalog tables are not supported")));
  
  	/*
  	 * concurrent index build on a system catalog is unsafe because we tend to
  	 * release locks before committing in catalogs
  	 */
  	if (concurrent &&
  		IsSystemRelation(heapRelation))
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("concurrent index creation on system catalog tables is not supported")));
  
  	/*
  	 * This case is currently not supported, but there's no way to ask for it
  	 * in the grammar anyway, so it can't happen.
  	 */
  	if (concurrent && is_exclusion)
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg_internal("concurrent index creation for exclusion constraints is not supported")));
  
  	/*
  	 * We cannot allow indexing a shared relation after initdb (because
  	 * there's no way to make the entry in other databases' pg_class).
  	 */
  	if (shared_relation && !IsBootstrapProcessingMode())
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
  				 errmsg("shared indexes cannot be created after initdb")));
  
  	/*
  	 * Shared relations must be in pg_global, too (last-ditch check)
  	 */
  	if (shared_relation && tableSpaceId != GLOBALTABLESPACE_OID)
  		elog(ERROR, "shared relations must be placed in pg_global tablespace");
  
  	/*
  	 * In YB mode, during bootstrap, a relation lookup by name will be a full-table scan
  	 * and slow because secondary indexes are not available yet. So we will skip this
  	 * duplicate name check as it will error later anyway when the indexes are created.
  	 */
  	if (!IsYugaByteEnabled() || !IsBootstrapProcessingMode())
  	{
  		/*
  		 * Check for duplicate name (both as to the index, and as to the
  		 * associated constraint if any).  Such cases would fail on the relevant
  		 * catalogs' unique indexes anyway, but we prefer to give a friendlier
  		 * error message.
  		 */
  		if (get_relname_relid(indexRelationName, namespaceId))
  		{
  			if ((flags & INDEX_CREATE_IF_NOT_EXISTS) != 0)
  			{
  				ereport(NOTICE,
  						(errcode(ERRCODE_DUPLICATE_TABLE),
  						 errmsg("relation \"%s\" already exists, skipping",
  								indexRelationName)));
  				heap_close(pg_class, RowExclusiveLock);
  				return InvalidOid;
  			}
  
  			ereport(ERROR,
  					(errcode(ERRCODE_DUPLICATE_TABLE),
  					 errmsg("relation \"%s\" already exists",
  							indexRelationName)));
  		}
  	}
  
  	if ((flags & INDEX_CREATE_ADD_CONSTRAINT) != 0 &&
  		ConstraintNameIsUsed(CONSTRAINT_RELATION, heapRelationId,
  							 indexRelationName))
  	{
  		/*
  		 * INDEX_CREATE_IF_NOT_EXISTS does not apply here, since the
  		 * conflicting constraint is not an index.
  		 */
  		ereport(ERROR,
  				(errcode(ERRCODE_DUPLICATE_OBJECT),
  				 errmsg("constraint \"%s\" for relation \"%s\" already exists",
  						indexRelationName, RelationGetRelationName(heapRelation))));
  	}
  
  	/*
  	 * construct tuple descriptor for index tuples
  	 */
  	indexTupDesc = ConstructTupleDescriptor(heapRelation,
  											indexInfo,
  											indexColNames,
  											accessMethodObjectId,
  											collationObjectId,
  											classObjectId);
  
  	/*
  	 * Allocate an OID for the index, unless we were told what to use.
  	 *
  	 * The OID will be the relfilenode as well, so make sure it doesn't
  	 * collide with either pg_class OIDs or existing physical files.
  	 */
  	if (!OidIsValid(indexRelationId))
  	{
  		/* Use binary-upgrade override for pg_class.oid/relfilenode? */
  		if (IsBinaryUpgrade)
  		{
  			if (!OidIsValid(binary_upgrade_next_index_pg_class_oid))
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  						 errmsg("pg_class index OID value not set when in binary upgrade mode")));
  
  			indexRelationId = binary_upgrade_next_index_pg_class_oid;
  			binary_upgrade_next_index_pg_class_oid = InvalidOid;
  		}
  		else
  		{
  			indexRelationId =
  				GetNewRelFileNode(tableSpaceId, pg_class, relpersistence);
  		}
  	}
  
  	/*
  	 * create the index relation's relcache entry and, if necessary, the
  	 * physical disk file. (If we fail further down, it's the smgr's
  	 * responsibility to remove the disk file again, if any.)
  	 */
  	indexRelation = heap_create(indexRelationName,
  								namespaceId,
  								tableSpaceId,
  								indexRelationId,
  								relFileNode,
  								indexTupDesc,
  								relkind,
  								relpersistence,
  								shared_relation,
  								mapped_relation,
  								allow_system_table_mods);
  
  	Assert(indexRelationId == RelationGetRelid(indexRelation));
  
  	/*
  	 * Create index in YugaByte only if it is a secondary index. Primary key is
  	 * an implicit part of the base table in YugaByte and doesn't need to be created.
  	 */
  	if (IsYBRelation(indexRelation) && !isprimary)
  	{
  		YBCCreateIndex(indexRelationName,
  					   indexInfo,
  					   indexTupDesc,
  					   coloptions,
  					   reloptions,
  					   indexRelationId,
  					   heapRelation,
  					   split_options,
  					   skip_index_backfill,
  					   tablegroupId);
  	}
  
  	/*
  	 * Obtain exclusive lock on it.  Although no other transactions can see it
  	 * until we commit, this prevents deadlock-risk complaints from lock
  	 * manager in cases such as CLUSTER.
  	 */
  	LockRelation(indexRelation, AccessExclusiveLock);
  
  	/*
  	 * Fill in fields of the index's pg_class entry that are not set correctly
  	 * by heap_create.
  	 *
  	 * XXX should have a cleaner way to create cataloged indexes
  	 */
  	indexRelation->rd_rel->relowner = heapRelation->rd_rel->relowner;
  	indexRelation->rd_rel->relam = accessMethodObjectId;
  	indexRelation->rd_rel->relhasoids = false;
  	indexRelation->rd_rel->relispartition = OidIsValid(parentIndexRelid);
  
  	/*
  	 * store index's pg_class entry
  	 */
  	InsertPgClassTuple(pg_class, indexRelation,
  					   RelationGetRelid(indexRelation),
  					   (Datum) 0,
  					   reloptions);
  
  	/* done with pg_class */
  	heap_close(pg_class, RowExclusiveLock);
  
  	/*
  	 * now update the object id's of all the attribute tuple forms in the
  	 * index relation's tuple descriptor
  	 */
  	InitializeAttributeOids(indexRelation,
  							indexInfo->ii_NumIndexAttrs,
  							indexRelationId);
  
  	/*
  	 * append ATTRIBUTE tuples for the index
  	 */
  	AppendAttributeTuples(indexRelation, indexInfo->ii_NumIndexAttrs);
  
  	/* ----------------
  	 *	  update pg_index
  	 *	  (append INDEX tuple)
  	 *
  	 *	  Note that this stows away a representation of "predicate".
  	 *	  (Or, could define a rule to maintain the predicate) --Nels, Feb '92
  	 * ----------------
  	 */
  	UpdateIndexRelation(indexRelationId, heapRelationId, parentIndexRelid,
  						indexInfo,
  						collationObjectId, classObjectId, coloptions,
  						isprimary, is_exclusion,
  						(constr_flags & INDEX_CONSTR_CREATE_DEFERRABLE) == 0,
  						!concurrent && !invalid,
  						!concurrent);
  
  	/*
  	 * Register relcache invalidation on the indexes' heap relation, to
  	 * maintain consistency of its index list
  	 */
  	CacheInvalidateRelcache(heapRelation);
  
  	/* update pg_inherits, if needed */
  	if (OidIsValid(parentIndexRelid))
  		StoreSingleInheritance(indexRelationId, parentIndexRelid, 1);
  
  	/*
  	 * Register constraint and dependencies for the index.
  	 *
  	 * If the index is from a CONSTRAINT clause, construct a pg_constraint
  	 * entry.  The index will be linked to the constraint, which in turn is
  	 * linked to the table.  If it's not a CONSTRAINT, we need to make a
  	 * dependency directly on the table.
  	 *
  	 * We don't need a dependency on the namespace, because there'll be an
  	 * indirect dependency via our parent table.
  	 *
  	 * During bootstrap we can't register any dependencies, and we don't try
  	 * to make a constraint either.
  	 */
  	if (!IsBootstrapProcessingMode())
  	{
  		ObjectAddress myself,
  					referenced;
  
  		myself.classId = RelationRelationId;
  		myself.objectId = indexRelationId;
  		myself.objectSubId = 0;
  
  		if ((flags & INDEX_CREATE_ADD_CONSTRAINT) != 0)
  		{
  			char		constraintType;
  			ObjectAddress localaddr;
  
  			if (isprimary)
  				constraintType = CONSTRAINT_PRIMARY;
  			else if (indexInfo->ii_Unique)
  				constraintType = CONSTRAINT_UNIQUE;
  			else if (is_exclusion)
  				constraintType = CONSTRAINT_EXCLUSION;
  			else
  			{
  				elog(ERROR, "constraint must be PRIMARY, UNIQUE or EXCLUDE");
  				constraintType = 0; /* keep compiler quiet */
  			}
  
  			localaddr = index_constraint_create(heapRelation,
  												indexRelationId,
  												parentConstraintId,
  												indexInfo,
  												indexRelationName,
  												constraintType,
  												constr_flags,
  												allow_system_table_mods,
  												is_internal);
  			if (constraintId)
  				*constraintId = localaddr.objectId;
  		}
  		else
  		{
  			bool		have_simple_col = false;
  			DependencyType deptype;
  
  			deptype = OidIsValid(parentIndexRelid) ? DEPENDENCY_INTERNAL_AUTO : DEPENDENCY_AUTO;
  
  			/* Create auto dependencies on simply-referenced columns */
  			for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
  			{
  				if (indexInfo->ii_IndexAttrNumbers[i] != 0)
  				{
  					referenced.classId = RelationRelationId;
  					referenced.objectId = heapRelationId;
  					referenced.objectSubId = indexInfo->ii_IndexAttrNumbers[i];
  
  					recordDependencyOn(&myself, &referenced, deptype);
  
  					have_simple_col = true;
  				}
  			}
  
  			/*
  			 * If there are no simply-referenced columns, give the index an
  			 * auto dependency on the whole table.  In most cases, this will
  			 * be redundant, but it might not be if the index expressions and
  			 * predicate contain no Vars or only whole-row Vars.
  			 */
  			if (!have_simple_col)
  			{
  				referenced.classId = RelationRelationId;
  				referenced.objectId = heapRelationId;
  				referenced.objectSubId = 0;
  
  				recordDependencyOn(&myself, &referenced, deptype);
  			}
  		}
  
  		/* Store dependency on parent index, if any */
  		if (OidIsValid(parentIndexRelid))
  		{
  			referenced.classId = RelationRelationId;
  			referenced.objectId = parentIndexRelid;
  			referenced.objectSubId = 0;
  
  			recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL_AUTO);
  		}
  
  		/* Store dependency on collations */
  		/* The default collation is pinned, so don't bother recording it */
  		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
  		{
  			if (OidIsValid(collationObjectId[i]) &&
  				collationObjectId[i] != DEFAULT_COLLATION_OID)
  			{
  				referenced.classId = CollationRelationId;
  				referenced.objectId = collationObjectId[i];
  				referenced.objectSubId = 0;
  
  				recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  			}
  		}
  
  		/* Store dependency on operator classes */
  		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
  		{
  			referenced.classId = OperatorClassRelationId;
  			referenced.objectId = classObjectId[i];
  			referenced.objectSubId = 0;
  
  			recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  		}
  
  		/* Store dependencies on anything mentioned in index expressions */
  		if (indexInfo->ii_Expressions)
  		{
  			recordDependencyOnSingleRelExpr(&myself,
  											(Node *) indexInfo->ii_Expressions,
  											heapRelationId,
  											DEPENDENCY_NORMAL,
  											DEPENDENCY_AUTO, false);
  		}
  
  		/* Store dependencies on anything mentioned in predicate */
  		if (indexInfo->ii_Predicate)
  		{
  			recordDependencyOnSingleRelExpr(&myself,
  											(Node *) indexInfo->ii_Predicate,
  											heapRelationId,
  											DEPENDENCY_NORMAL,
  											DEPENDENCY_AUTO, false);
  		}
  	}
  	else
  	{
  		/* Bootstrap mode - assert we weren't asked for constraint support */
  		Assert((flags & INDEX_CREATE_ADD_CONSTRAINT) == 0);
  	}
  
  	/* Post creation hook for new index */
  	InvokeObjectPostCreateHookArg(RelationRelationId,
  								  indexRelationId, 0, is_internal);
  
  	/*
  	 * Advance the command counter so that we can see the newly-entered
  	 * catalog tuples for the index.
  	 */
  	CommandCounterIncrement();
  
  	/*
  	 * In bootstrap mode, we have to fill in the index strategy structure with
  	 * information from the catalogs.  If we aren't bootstrapping, then the
  	 * relcache entry has already been rebuilt thanks to sinval update during
  	 * CommandCounterIncrement.
  	 */
  	if (IsBootstrapProcessingMode() || IsYugaByteEnabled())
  		RelationInitIndexAccessInfo(indexRelation);
  	else
  		Assert(indexRelation->rd_indexcxt != NULL);
  
  	indexRelation->rd_index->indnkeyatts = indexInfo->ii_NumIndexKeyAttrs;
  
  	/*
  	 * If this is bootstrap (initdb) time, then we don't actually fill in the
  	 * index yet.  We'll be creating more indexes and classes later, so we
  	 * delay filling them in until just before we're done with bootstrapping.
  	 * Similarly, if the caller specified to skip the build then filling the
  	 * index is delayed till later (ALTER TABLE can save work in some cases
  	 * with this).  Otherwise, we call the AM routine that constructs the
  	 * index.
  	 */
  	if (IsBootstrapProcessingMode())
  	{
  		index_register(heapRelationId, indexRelationId, indexInfo);
  	}
  	else if ((flags & INDEX_CREATE_SKIP_BUILD) != 0)
  	{
  		/*
  		 * Caller is responsible for filling the index later on.  However,
  		 * we'd better make sure that the heap relation is correctly marked as
  		 * having an index.
  		 */
  		index_update_stats(heapRelation,
  						   true,
  						   -1.0);
  		/* Make the above update visible */
  		CommandCounterIncrement();
  	}
  	else
  	{
  		index_build(heapRelation, indexRelation, indexInfo, isprimary, false,
  					true);
  	}
  
  	/*
  	 * Close the index; but we keep the lock that we acquired above until end
  	 * of transaction.  Closing the heap is caller's responsibility.
  	 */
  	index_close(indexRelation, NoLock);
  
  	return indexRelationId;
  }
  
  /*
   * index_constraint_create
   *
   * Set up a constraint associated with an index.  Return the new constraint's
   * address.
   *
   * heapRelation: table owning the index (must be suitably locked by caller)
   * indexRelationId: OID of the index
   * parentConstraintId: if constraint is on a partition, the OID of the
   *		constraint in the parent.
   * indexInfo: same info executor uses to insert into the index
   * constraintName: what it say (generally, should match name of index)
   * constraintType: one of CONSTRAINT_PRIMARY, CONSTRAINT_UNIQUE, or
   *		CONSTRAINT_EXCLUSION
   * flags: bitmask that can include any combination of these bits:
   *		INDEX_CONSTR_CREATE_MARK_AS_PRIMARY: index is a PRIMARY KEY
   *		INDEX_CONSTR_CREATE_DEFERRABLE: constraint is DEFERRABLE
   *		INDEX_CONSTR_CREATE_INIT_DEFERRED: constraint is INITIALLY DEFERRED
   *		INDEX_CONSTR_CREATE_UPDATE_INDEX: update the pg_index row
   *		INDEX_CONSTR_CREATE_REMOVE_OLD_DEPS: remove existing dependencies
   *			of index on table's columns
   * allow_system_table_mods: allow table to be a system catalog
   * is_internal: index is constructed due to internal process
   */
  ObjectAddress
  index_constraint_create(Relation heapRelation,
  						Oid indexRelationId,
  						Oid parentConstraintId,
  						IndexInfo *indexInfo,
  						const char *constraintName,
  						char constraintType,
  						bits16 constr_flags,
  						bool allow_system_table_mods,
  						bool is_internal)
  {
  	Oid			namespaceId = RelationGetNamespace(heapRelation);
  	ObjectAddress myself,
  				referenced;
  	Oid			conOid;
  	bool		deferrable;
  	bool		initdeferred;
  	bool		mark_as_primary;
  	bool		islocal;
  	bool		noinherit;
  	int			inhcount;
  
  	deferrable = (constr_flags & INDEX_CONSTR_CREATE_DEFERRABLE) != 0;
  	initdeferred = (constr_flags & INDEX_CONSTR_CREATE_INIT_DEFERRED) != 0;
  	mark_as_primary = (constr_flags & INDEX_CONSTR_CREATE_MARK_AS_PRIMARY) != 0;
  
  	/* constraint creation support doesn't work while bootstrapping */
  	Assert(!IsBootstrapProcessingMode());
  
  	/* enforce system-table restriction */
  	if (!allow_system_table_mods &&
  		IsSystemRelation(heapRelation) &&
  		IsNormalProcessingMode())
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("user-defined indexes on system catalog tables are not supported")));
  
  	/* primary/unique constraints shouldn't have any expressions */
  	if (indexInfo->ii_Expressions &&
  		constraintType != CONSTRAINT_EXCLUSION)
  		elog(ERROR, "constraints cannot have index expressions");
  
  	/*
  	 * If we're manufacturing a constraint for a pre-existing index, we need
  	 * to get rid of the existing auto dependencies for the index (the ones
  	 * that index_create() would have made instead of calling this function).
  	 *
  	 * Note: this code would not necessarily do the right thing if the index
  	 * has any expressions or predicate, but we'd never be turning such an
  	 * index into a UNIQUE or PRIMARY KEY constraint.
  	 */
  	if (constr_flags & INDEX_CONSTR_CREATE_REMOVE_OLD_DEPS)
  		deleteDependencyRecordsForClass(RelationRelationId, indexRelationId,
  										RelationRelationId, DEPENDENCY_AUTO);
  
  	if (OidIsValid(parentConstraintId))
  	{
  		islocal = false;
  		inhcount = 1;
  		noinherit = false;
  	}
  	else
  	{
  		islocal = true;
  		inhcount = 0;
  		noinherit = true;
  	}
  
  	/*
  	 * Construct a pg_constraint entry.
  	 */
  	conOid = CreateConstraintEntry(constraintName,
  								   namespaceId,
  								   constraintType,
  								   deferrable,
  								   initdeferred,
  								   true,
  								   parentConstraintId,
  								   RelationGetRelid(heapRelation),
  								   indexInfo->ii_IndexAttrNumbers,
  								   indexInfo->ii_NumIndexKeyAttrs,
  								   indexInfo->ii_NumIndexAttrs,
  								   InvalidOid,	/* no domain */
  								   indexRelationId, /* index OID */
  								   InvalidOid,	/* no foreign key */
  								   NULL,
  								   NULL,
  								   NULL,
  								   NULL,
  								   0,
  								   ' ',
  								   ' ',
  								   ' ',
  								   indexInfo->ii_ExclusionOps,
  								   NULL,	/* no check constraint */
  								   NULL,
  								   NULL,
  								   islocal,
  								   inhcount,
  								   noinherit,
  								   is_internal);
  
  	/*
  	 * Register the index as internally dependent on the constraint.
  	 *
  	 * Note that the constraint has a dependency on the table, so we don't
  	 * need (or want) any direct dependency from the index to the table.
  	 */
  	myself.classId = RelationRelationId;
  	myself.objectId = indexRelationId;
  	myself.objectSubId = 0;
  
  	referenced.classId = ConstraintRelationId;
  	referenced.objectId = conOid;
  	referenced.objectSubId = 0;
  
  	recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL);
  
  	/*
  	 * Also, if this is a constraint on a partition, mark it as depending on
  	 * the constraint in the parent.
  	 */
  	if (OidIsValid(parentConstraintId))
  	{
  		ObjectAddress parentConstr;
  
  		ObjectAddressSet(parentConstr, ConstraintRelationId, parentConstraintId);
  		recordDependencyOn(&referenced, &parentConstr, DEPENDENCY_INTERNAL_AUTO);
  	}
  
  	/*
  	 * If the constraint is deferrable, create the deferred uniqueness
  	 * checking trigger.  (The trigger will be given an internal dependency on
  	 * the constraint by CreateTrigger.)
  	 */
  	if (deferrable)
  	{
  		CreateTrigStmt *trigger;
  
  		trigger = makeNode(CreateTrigStmt);
  		trigger->trigname = (constraintType == CONSTRAINT_PRIMARY) ?
  			"PK_ConstraintTrigger" :
  			"Unique_ConstraintTrigger";
  		trigger->relation = NULL;
  		trigger->funcname = SystemFuncName("unique_key_recheck");
  		trigger->args = NIL;
  		trigger->row = true;
  		trigger->timing = TRIGGER_TYPE_AFTER;
  		trigger->events = TRIGGER_TYPE_INSERT | TRIGGER_TYPE_UPDATE;
  		trigger->columns = NIL;
  		trigger->whenClause = NULL;
  		trigger->isconstraint = true;
  		trigger->deferrable = true;
  		trigger->initdeferred = initdeferred;
  		trigger->constrrel = NULL;
  
  		(void) CreateTrigger(trigger, NULL, RelationGetRelid(heapRelation),
  							 InvalidOid, conOid, indexRelationId, InvalidOid,
  							 InvalidOid, NULL, true, false);
  	}
  
  	/*
  	 * If needed, mark the index as primary and/or deferred in pg_index.
  	 *
  	 * Note: When making an existing index into a constraint, caller must have
  	 * a table lock that prevents concurrent table updates; otherwise, there
  	 * is a risk that concurrent readers of the table will miss seeing this
  	 * index at all.
  	 */
  	if ((constr_flags & INDEX_CONSTR_CREATE_UPDATE_INDEX) &&
  		(mark_as_primary || deferrable))
  	{
  		Relation	pg_index;
  		HeapTuple	indexTuple;
  		Form_pg_index indexForm;
  		bool		dirty = false;
  
  		pg_index = heap_open(IndexRelationId, RowExclusiveLock);
  
  		indexTuple = SearchSysCacheCopy1(INDEXRELID,
  										 ObjectIdGetDatum(indexRelationId));
  		if (!HeapTupleIsValid(indexTuple))
  			elog(ERROR, "cache lookup failed for index %u", indexRelationId);
  		indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
  
  		if (mark_as_primary && !indexForm->indisprimary)
  		{
  			indexForm->indisprimary = true;
  			dirty = true;
  		}
  
  		if (deferrable && indexForm->indimmediate)
  		{
  			indexForm->indimmediate = false;
  			dirty = true;
  		}
  
  		if (dirty)
  		{
  			CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
  
  			InvokeObjectPostAlterHookArg(IndexRelationId, indexRelationId, 0,
  										 InvalidOid, is_internal);
  		}
  
  		heap_freetuple(indexTuple);
  		heap_close(pg_index, RowExclusiveLock);
  	}
  
  	return referenced;
  }
  
  /*
   *		index_drop
   *
   * NOTE: this routine should now only be called through performDeletion(),
   * else associated dependencies won't be cleaned up.
   */
  void
  index_drop(Oid indexId, bool concurrent)
  {
  	Oid			heapId;
  	Relation	userHeapRelation;
  	Relation	userIndexRelation;
  	Relation	indexRelation;
  	HeapTuple	tuple;
  	bool		hasexprs;
  	LockRelId	heaprelid,
  				indexrelid;
  	LOCKTAG		heaplocktag;
  	LOCKMODE	lockmode;
  
  	/*
  	 * To drop an index safely, we must grab exclusive lock on its parent
  	 * table.  Exclusive lock on the index alone is insufficient because
  	 * another backend might be about to execute a query on the parent table.
  	 * If it relies on a previously cached list of index OIDs, then it could
  	 * attempt to access the just-dropped index.  We must therefore take a
  	 * table lock strong enough to prevent all queries on the table from
  	 * proceeding until we commit and send out a shared-cache-inval notice
  	 * that will make them update their index lists.
  	 *
  	 * In the concurrent case we avoid this requirement by disabling index use
  	 * in multiple steps and waiting out any transactions that might be using
  	 * the index, so we don't need exclusive lock on the parent table. Instead
  	 * we take ShareUpdateExclusiveLock, to ensure that two sessions aren't
  	 * doing CREATE/DROP INDEX CONCURRENTLY on the same index.  (We will get
  	 * AccessExclusiveLock on the index below, once we're sure nobody else is
  	 * using it.)
  	 */
  	heapId = IndexGetRelation(indexId, false);
  	lockmode = concurrent ? ShareUpdateExclusiveLock : AccessExclusiveLock;
  	userHeapRelation = heap_open(heapId, lockmode);
  	userIndexRelation = index_open(indexId, lockmode);
  
  	/*
  	 * We might still have open queries using it in our own session, which the
  	 * above locking won't prevent, so test explicitly.
  	 */
  	CheckTableNotInUse(userIndexRelation, "DROP INDEX");
  
  	/*
  	 * Drop Index Concurrently is more or less the reverse process of Create
  	 * Index Concurrently.
  	 *
  	 * First we unset indisvalid so queries starting afterwards don't use the
  	 * index to answer queries anymore.  We have to keep indisready = true so
  	 * transactions that are still scanning the index can continue to see
  	 * valid index contents.  For instance, if they are using READ COMMITTED
  	 * mode, and another transaction makes changes and commits, they need to
  	 * see those new tuples in the index.
  	 *
  	 * After all transactions that could possibly have used the index for
  	 * queries end, we can unset indisready and indislive, then wait till
  	 * nobody could be touching it anymore.  (Note: we need indislive because
  	 * this state must be distinct from the initial state during CREATE INDEX
  	 * CONCURRENTLY, which has indislive true while indisready and indisvalid
  	 * are false.  That's because in that state, transactions must examine the
  	 * index for HOT-safety decisions, while in this state we don't want them
  	 * to open it at all.)
  	 *
  	 * Since all predicate locks on the index are about to be made invalid, we
  	 * must promote them to predicate locks on the heap.  In the
  	 * non-concurrent case we can just do that now.  In the concurrent case
  	 * it's a bit trickier.  The predicate locks must be moved when there are
  	 * no index scans in progress on the index and no more can subsequently
  	 * start, so that no new predicate locks can be made on the index.  Also,
  	 * they must be moved before heap inserts stop maintaining the index, else
  	 * the conflict with the predicate lock on the index gap could be missed
  	 * before the lock on the heap relation is in place to detect a conflict
  	 * based on the heap tuple insert.
  	 */
  	if (concurrent)
  	{
  		/*
  		 * We must commit our transaction in order to make the first pg_index
  		 * state update visible to other sessions.  If the DROP machinery has
  		 * already performed any other actions (removal of other objects,
  		 * pg_depend entries, etc), the commit would make those actions
  		 * permanent, which would leave us with inconsistent catalog state if
  		 * we fail partway through the following sequence.  Since DROP INDEX
  		 * CONCURRENTLY is restricted to dropping just one index that has no
  		 * dependencies, we should get here before anything's been done ---
  		 * but let's check that to be sure.  We can verify that the current
  		 * transaction has not executed any transactional updates by checking
  		 * that no XID has been assigned.
  		 */
  		if (GetTopTransactionIdIfAny() != InvalidTransactionId)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("DROP INDEX CONCURRENTLY must be first action in transaction")));
  
  		/*
  		 * Mark index invalid by updating its pg_index entry
  		 */
  		index_set_state_flags(indexId, INDEX_DROP_CLEAR_VALID);
  
  		/*
  		 * Invalidate the relcache for the table, so that after this commit
  		 * all sessions will refresh any cached plans that might reference the
  		 * index.
  		 */
  		CacheInvalidateRelcache(userHeapRelation);
  
  		/* save lockrelid and locktag for below, then close but keep locks */
  		heaprelid = userHeapRelation->rd_lockInfo.lockRelId;
  		SET_LOCKTAG_RELATION(heaplocktag, heaprelid.dbId, heaprelid.relId);
  		indexrelid = userIndexRelation->rd_lockInfo.lockRelId;
  
  		heap_close(userHeapRelation, NoLock);
  		index_close(userIndexRelation, NoLock);
  
  		/*
  		 * We must commit our current transaction so that the indisvalid
  		 * update becomes visible to other transactions; then start another.
  		 * Note that any previously-built data structures 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.
  		 */
  		LockRelationIdForSession(&heaprelid, ShareUpdateExclusiveLock);
  		LockRelationIdForSession(&indexrelid, ShareUpdateExclusiveLock);
  
  		PopActiveSnapshot();
  		CommitTransactionCommand();
  		StartTransactionCommand();
  
  		/*
  		 * Now we must wait until no running transaction could be using the
  		 * index for a query.  Use AccessExclusiveLock here to check for
  		 * running transactions that hold locks of any kind on the table. Note
  		 * we do not need to worry about xacts that open the table for reading
  		 * after this point; they will see the index as invalid when they open
  		 * the relation.
  		 *
  		 * 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.
  		 */
  		WaitForLockers(heaplocktag, AccessExclusiveLock);
  
  		/*
  		 * No more predicate locks will be acquired on this index, and we're
  		 * about to stop doing inserts into the index which could show
  		 * conflicts with existing predicate locks, so now is the time to move
  		 * them to the heap relation.
  		 */
  		userHeapRelation = heap_open(heapId, ShareUpdateExclusiveLock);
  		userIndexRelation = index_open(indexId, ShareUpdateExclusiveLock);
  		TransferPredicateLocksToHeapRelation(userIndexRelation);
  
  		/*
  		 * Now we are sure that nobody uses the index for queries; they just
  		 * might have it open for updating it.  So now we can unset indisready
  		 * and indislive, then wait till nobody could be using it at all
  		 * anymore.
  		 */
  		index_set_state_flags(indexId, INDEX_DROP_SET_DEAD);
  
  		/*
  		 * Invalidate the relcache for the table, so that after this commit
  		 * all sessions will refresh the table's index list.  Forgetting just
  		 * the index's relcache entry is not enough.
  		 */
  		CacheInvalidateRelcache(userHeapRelation);
  
  		/*
  		 * Close the relations again, though still holding session lock.
  		 */
  		heap_close(userHeapRelation, NoLock);
  		index_close(userIndexRelation, NoLock);
  
  		/*
  		 * Again, commit the transaction to make the pg_index update visible
  		 * to other sessions.
  		 */
  		CommitTransactionCommand();
  		StartTransactionCommand();
  
  		/*
  		 * Wait till every transaction that saw the old index state has
  		 * finished.
  		 */
  		WaitForLockers(heaplocktag, AccessExclusiveLock);
  
  		/*
  		 * Re-open relations to allow us to complete our actions.
  		 *
  		 * At this point, nothing should be accessing the index, but lets
  		 * leave nothing to chance and grab AccessExclusiveLock on the index
  		 * before the physical deletion.
  		 */
  		userHeapRelation = heap_open(heapId, ShareUpdateExclusiveLock);
  		userIndexRelation = index_open(indexId, AccessExclusiveLock);
  	}
  	else
  	{
  		/* Not concurrent, so just transfer predicate locks and we're good */
  		TransferPredicateLocksToHeapRelation(userIndexRelation);
  	}
  
  	/*
  	 * Schedule physical removal of the files (if any)
  	 * If the relation is a Yugabyte relation, there aren't any physical files to
  	 * remove.
  	 */
  	if (!IsYBRelation(userIndexRelation) &&
  		userIndexRelation->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
  		RelationDropStorage(userIndexRelation);
  
  	/*
  	 * Close and flush the index's relcache entry, to ensure relcache doesn't
  	 * try to rebuild it while we're deleting catalog entries. We keep the
  	 * lock though.
  	 */
  	index_close(userIndexRelation, NoLock);
  
  	RelationForgetRelation(indexId);
  
  	/*
  	 * fix INDEX relation, and check for expressional index
  	 */
  	indexRelation = heap_open(IndexRelationId, RowExclusiveLock);
  
  	tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexId));
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "cache lookup failed for index %u", indexId);
  
  	hasexprs = !heap_attisnull(tuple, Anum_pg_index_indexprs,
  							   RelationGetDescr(indexRelation));
  
  	CatalogTupleDelete(indexRelation, tuple);
  
  	ReleaseSysCache(tuple);
  	heap_close(indexRelation, RowExclusiveLock);
  
  	/*
  	 * if it has any expression columns, we might have stored statistics about
  	 * them.
  	 */
  	if (hasexprs)
  		RemoveStatistics(indexId, 0);
  
  	/*
  	 * fix ATTRIBUTE relation
  	 */
  	DeleteAttributeTuples(indexId);
  
  	/*
  	 * fix RELATION relation
  	 */
  	DeleteRelationTuple(indexId);
  
  	/*
  	 * fix INHERITS relation
  	 */
  	DeleteInheritsTuple(indexId, InvalidOid);
  
  	/*
  	 * We are presently too lazy to attempt to compute the new correct value
  	 * of relhasindex (the next VACUUM will fix it if necessary). So there is
  	 * no need to update the pg_class tuple for the owning relation. But we
  	 * must send out a shared-cache-inval notice on the owning relation to
  	 * ensure other backends update their relcache lists of indexes.  (In the
  	 * concurrent case, this is redundant but harmless.)
  	 */
  	CacheInvalidateRelcache(userHeapRelation);
  
  	/*
  	 * Close owning rel, but keep lock
  	 */
  	heap_close(userHeapRelation, NoLock);
  
  	/*
  	 * Release the session locks before we go.
  	 */
  	if (concurrent)
  	{
  		UnlockRelationIdForSession(&heaprelid, ShareUpdateExclusiveLock);
  		UnlockRelationIdForSession(&indexrelid, ShareUpdateExclusiveLock);
  	}
  }
  
  /* ----------------------------------------------------------------
   *						index_build support
   * ----------------------------------------------------------------
   */
  
  /* ----------------
   *		BuildIndexInfo
   *			Construct an IndexInfo record for an open index
   *
   * IndexInfo stores the information about the index that's needed by
   * FormIndexDatum, which is used for both index_build() and later insertion
   * of individual index tuples.  Normally we build an IndexInfo for an index
   * just once per command, and then use it for (potentially) many tuples.
   * ----------------
   */
  IndexInfo *
  BuildIndexInfo(Relation index)
  {
  	IndexInfo  *ii = makeNode(IndexInfo);
  	Form_pg_index indexStruct = index->rd_index;
  	int			i;
  	int			numAtts;
  
  	/* check the number of keys, and copy attr numbers into the IndexInfo */
  	numAtts = indexStruct->indnatts;
  	if (numAtts < 1 || numAtts > INDEX_MAX_KEYS)
  		elog(ERROR, "invalid indnatts %d for index %u",
  			 numAtts, RelationGetRelid(index));
  	ii->ii_NumIndexAttrs = numAtts;
  	ii->ii_NumIndexKeyAttrs = indexStruct->indnkeyatts;
  	Assert(ii->ii_NumIndexKeyAttrs != 0);
  	Assert(ii->ii_NumIndexKeyAttrs <= ii->ii_NumIndexAttrs);
  
  	for (i = 0; i < numAtts; i++)
  		ii->ii_IndexAttrNumbers[i] = indexStruct->indkey.values[i];
  
  	/* fetch any expressions needed for expressional indexes */
  	ii->ii_Expressions = RelationGetIndexExpressions(index);
  	ii->ii_ExpressionsState = NIL;
  
  	/* fetch index predicate if any */
  	ii->ii_Predicate = RelationGetIndexPredicate(index);
  	ii->ii_PredicateState = NULL;
  
  	/* fetch exclusion constraint info if any */
  	if (indexStruct->indisexclusion)
  	{
  		RelationGetExclusionInfo(index,
  								 &ii->ii_ExclusionOps,
  								 &ii->ii_ExclusionProcs,
  								 &ii->ii_ExclusionStrats);
  	}
  	else
  	{
  		ii->ii_ExclusionOps = NULL;
  		ii->ii_ExclusionProcs = NULL;
  		ii->ii_ExclusionStrats = NULL;
  	}
  
  	/* other info */
  	ii->ii_Unique = indexStruct->indisunique;
  	ii->ii_ReadyForInserts = IndexIsReady(indexStruct);
  	/* assume not doing speculative insertion for now */
  	ii->ii_UniqueOps = NULL;
  	ii->ii_UniqueProcs = NULL;
  	ii->ii_UniqueStrats = NULL;
  
  	/* initialize index-build state to default */
  	ii->ii_Concurrent = false;
  	ii->ii_BrokenHotChain = false;
  	ii->ii_ParallelWorkers = 0;
  
  	/* set up for possible use by index AM */
  	ii->ii_Am = index->rd_rel->relam;
  	ii->ii_AmCache = NULL;
  	ii->ii_Context = GetCurrentMemoryContext();
  
  	return ii;
  }
  
  /*
   * CompareIndexInfo
   *		Return whether the properties of two indexes (in different tables)
   *		indicate that they have the "same" definitions.
   *
   * Note: passing collations and opfamilies separately is a kludge.  Adding
   * them to IndexInfo may result in better coding here and elsewhere.
   *
   * Use convert_tuples_by_name_map(index2, index1) to build the attmap.
   */
  bool
  CompareIndexInfo(IndexInfo *info1, IndexInfo *info2,
  				 Oid *collations1, Oid *collations2,
  				 Oid *opfamilies1, Oid *opfamilies2,
  				 AttrNumber *attmap, int maplen)
  {
  	int			i;
  
  	if (info1->ii_Unique != info2->ii_Unique)
  		return false;
  
  	/* indexes are only equivalent if they have the same access method */
  	if (info1->ii_Am != info2->ii_Am)
  		return false;
  
  	/* and same number of attributes */
  	if (info1->ii_NumIndexAttrs != info2->ii_NumIndexAttrs)
  		return false;
  
  	/* and same number of key attributes */
  	if (info1->ii_NumIndexKeyAttrs != info2->ii_NumIndexKeyAttrs)
  		return false;
  
  
  	/*
  	 * and columns match through the attribute map (actual attribute numbers
  	 * might differ!)  Note that this implies that index columns that are
  	 * expressions appear in the same positions.  We will next compare the
  	 * expressions themselves.
  	 */
  	for (i = 0; i < info1->ii_NumIndexAttrs; i++)
  	{
  		if (maplen < info2->ii_IndexAttrNumbers[i])
  			elog(ERROR, "incorrect attribute map");
  
  		/* ignore expressions at this stage */
  		if ((info1->ii_IndexAttrNumbers[i] != InvalidAttrNumber) &&
  			(attmap[info2->ii_IndexAttrNumbers[i] - 1] !=
  			 info1->ii_IndexAttrNumbers[i]))
  			return false;
  
  		/* collation and opfamily is not valid for including columns */
  		if (i >= info1->ii_NumIndexKeyAttrs)
  			continue;
  
  		if (collations1[i] != collations2[i])
  			return false;
  		if (opfamilies1[i] != opfamilies2[i])
  			return false;
  	}
  
  	/*
  	 * For expression indexes: either both are expression indexes, or neither
  	 * is; if they are, make sure the expressions match.
  	 */
  	if ((info1->ii_Expressions != NIL) != (info2->ii_Expressions != NIL))
  		return false;
  	if (info1->ii_Expressions != NIL)
  	{
  		bool		found_whole_row;
  		Node	   *mapped;
  
  		mapped = map_variable_attnos((Node *) info2->ii_Expressions,
  									 1, 0, attmap, maplen,
  									 InvalidOid, &found_whole_row);
  		if (found_whole_row)
  		{
  			/*
  			 * we could throw an error here, but seems out of scope for this
  			 * routine.
  			 */
  			return false;
  		}
  
  		if (!equal(info1->ii_Expressions, mapped))
  			return false;
  	}
  
  	/* Partial index predicates must be identical, if they exist */
  	if ((info1->ii_Predicate == NULL) != (info2->ii_Predicate == NULL))
  		return false;
  	if (info1->ii_Predicate != NULL)
  	{
  		bool		found_whole_row;
  		Node	   *mapped;
  
  		mapped = map_variable_attnos((Node *) info2->ii_Predicate,
  									 1, 0, attmap, maplen,
  									 InvalidOid, &found_whole_row);
  		if (found_whole_row)
  		{
  			/*
  			 * we could throw an error here, but seems out of scope for this
  			 * routine.
  			 */
  			return false;
  		}
  		if (!equal(info1->ii_Predicate, mapped))
  			return false;
  	}
  
  	/* No support currently for comparing exclusion indexes. */
  	if (info1->ii_ExclusionOps != NULL || info2->ii_ExclusionOps != NULL)
  		return false;
  
  	return true;
  }
  
  /* ----------------
   *		BuildSpeculativeIndexInfo
   *			Add extra state to IndexInfo record
   *
   * For unique indexes, we usually don't want to add info to the IndexInfo for
   * checking uniqueness, since the B-Tree AM handles that directly.  However,
   * in the case of speculative insertion, additional support is required.
   *
   * Do this processing here rather than in BuildIndexInfo() to not incur the
   * overhead in the common non-speculative cases.
   * ----------------
   */
  void
  BuildSpeculativeIndexInfo(Relation index, IndexInfo *ii)
  {
  	int			indnkeyatts;
  	int			i;
  
  	indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index);
  
  	/*
  	 * fetch info for checking unique indexes
  	 */
  	Assert(ii->ii_Unique);
  
  	if (index->rd_rel->relam != BTREE_AM_OID &&
  		index->rd_rel->relam != LSM_AM_OID)
  		elog(ERROR, "unexpected non-btree/lsm speculative unique index");
  
  	ii->ii_UniqueOps = (Oid *) palloc(sizeof(Oid) * indnkeyatts);
  	ii->ii_UniqueProcs = (Oid *) palloc(sizeof(Oid) * indnkeyatts);
  	ii->ii_UniqueStrats = (uint16 *) palloc(sizeof(uint16) * indnkeyatts);
  
  	/*
  	 * We have to look up the operator's strategy number.  This provides a
  	 * cross-check that the operator does match the index.
  	 */
  	/* We need the func OIDs and strategy numbers too */
  	for (i = 0; i < indnkeyatts; i++)
  	{
  		ii->ii_UniqueStrats[i] = BTEqualStrategyNumber;
  		ii->ii_UniqueOps[i] =
  			get_opfamily_member(index->rd_opfamily[i],
  								index->rd_opcintype[i],
  								index->rd_opcintype[i],
  								ii->ii_UniqueStrats[i]);
  		if (!OidIsValid(ii->ii_UniqueOps[i]))
  			elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
  				 ii->ii_UniqueStrats[i], index->rd_opcintype[i],
  				 index->rd_opcintype[i], index->rd_opfamily[i]);
  		ii->ii_UniqueProcs[i] = get_opcode(ii->ii_UniqueOps[i]);
  	}
  }
  
  /* ----------------
   *		FormIndexDatum
   *			Construct values[] and isnull[] arrays for a new index tuple.
   *
   *	indexInfo		Info about the index
   *	slot			Heap tuple for which we must prepare an index entry
   *	estate			executor state for evaluating any index expressions
   *	values			Array of index Datums (output area)
   *	isnull			Array of is-null indicators (output area)
   *
   * When there are no index expressions, estate may be NULL.  Otherwise it
   * must be supplied, *and* the ecxt_scantuple slot of its per-tuple expr
   * context must point to the heap tuple passed in.
   *
   * Notice we don't actually call index_form_tuple() here; we just prepare
   * its input arrays values[] and isnull[].  This is because the index AM
   * may wish to alter the data before storage.
   * ----------------
   */
  void
  FormIndexDatum(IndexInfo *indexInfo,
  			   TupleTableSlot *slot,
  			   EState *estate,
  			   Datum *values,
  			   bool *isnull)
  {
  	ListCell   *indexpr_item;
  	int			i;
  
  	if (indexInfo->ii_Expressions != NIL &&
  		indexInfo->ii_ExpressionsState == NIL)
  	{
  		/* First time through, set up expression evaluation state */
  		indexInfo->ii_ExpressionsState =
  			ExecPrepareExprList(indexInfo->ii_Expressions, estate);
  		/* Check caller has set up context correctly */
  		Assert(GetPerTupleExprContext(estate)->ecxt_scantuple == slot);
  	}
  	indexpr_item = list_head(indexInfo->ii_ExpressionsState);
  
  	for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
  	{
  		int			keycol = indexInfo->ii_IndexAttrNumbers[i];
  		Datum		iDatum;
  		bool		isNull;
  
  		if (keycol != 0)
  		{
  			/*
  			 * Plain index column; get the value we need directly from the
  			 * heap tuple.
  			 */
  			iDatum = slot_getattr(slot, keycol, &isNull);
  		}
  		else
  		{
  			/*
  			 * Index expression --- need to evaluate it.
  			 */
  			if (indexpr_item == NULL)
  				elog(ERROR, "wrong number of index expressions");
  			iDatum = ExecEvalExprSwitchContext((ExprState *) lfirst(indexpr_item),
  											   GetPerTupleExprContext(estate),
  											   &isNull);
  			indexpr_item = lnext(indexpr_item);
  		}
  		values[i] = iDatum;
  		isnull[i] = isNull;
  	}
  
  	if (indexpr_item != NULL)
  		elog(ERROR, "wrong number of index expressions");
  }
  
  
  /*
   * index_update_stats --- update pg_class entry after CREATE INDEX or REINDEX
   *
   * This routine updates the pg_class row of either an index or its parent
   * relation after CREATE INDEX or REINDEX.  Its rather bizarre API is designed
   * to ensure we can do all the necessary work in just one update.
   *
   * hasindex: set relhasindex to this value
   * reltuples: if >= 0, set reltuples to this value; else no change
   *
   * If reltuples >= 0, relpages and relallvisible are also updated (using
   * RelationGetNumberOfBlocks() and visibilitymap_count()).
   *
   * NOTE: an important side-effect of this operation is that an SI invalidation
   * message is sent out to all backends --- including me --- causing relcache
   * entries to be flushed or updated with the new data.  This must happen even
   * if we find that no change is needed in the pg_class row.  When updating
   * a heap entry, this ensures that other backends find out about the new
   * index.  When updating an index, it's important because some index AMs
   * expect a relcache flush to occur after REINDEX.
   */
  static void
  index_update_stats(Relation rel,
  				   bool hasindex,
  				   double reltuples)
  {
  	Oid			relid = RelationGetRelid(rel);
  	Relation	pg_class;
  	HeapTuple	tuple;
  	Form_pg_class rd_rel;
  	bool		dirty;
  
  	/*
  	 * We always update the pg_class row using a non-transactional,
  	 * overwrite-in-place update.  There are several reasons for this:
  	 *
  	 * 1. In bootstrap mode, we have no choice --- UPDATE wouldn't work.
  	 *
  	 * 2. We could be reindexing pg_class itself, in which case we can't move
  	 * its pg_class row because CatalogTupleInsert/CatalogTupleUpdate might
  	 * not know about all the indexes yet (see reindex_relation).
  	 *
  	 * 3. Because we execute CREATE INDEX with just share lock on the parent
  	 * rel (to allow concurrent index creations), an ordinary update could
  	 * suffer a tuple-concurrently-updated failure against another CREATE
  	 * INDEX committing at about the same time.  We can avoid that by having
  	 * them both do nontransactional updates (we assume they will both be
  	 * trying to change the pg_class row to the same thing, so it doesn't
  	 * matter which goes first).
  	 *
  	 * It is safe to use a non-transactional update even though our
  	 * transaction could still fail before committing.  Setting relhasindex
  	 * true is safe even if there are no indexes (VACUUM will eventually fix
  	 * it).  And of course the new relpages and reltuples counts are correct
  	 * regardless.  However, we don't want to change relpages (or
  	 * relallvisible) if the caller isn't providing an updated reltuples
  	 * count, because that would bollix the reltuples/relpages ratio which is
  	 * what's really important.
  	 */
  
  	pg_class = heap_open(RelationRelationId, RowExclusiveLock);
  
  	/*
  	 * Make a copy of the tuple to update.  Normally we use the syscache, but
  	 * we can't rely on that during bootstrap or while reindexing pg_class
  	 * itself.
  	 */
  	if (IsBootstrapProcessingMode() ||
  		ReindexIsProcessingHeap(RelationRelationId))
  	{
  		/* don't assume syscache will work */
  		HeapScanDesc pg_class_scan;
  		ScanKeyData key[1];
  
  		ScanKeyInit(&key[0],
  					ObjectIdAttributeNumber,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(relid));
  
  		pg_class_scan = heap_beginscan_catalog(pg_class, 1, key);
  		tuple = heap_getnext(pg_class_scan, ForwardScanDirection);
  		tuple = heap_copytuple(tuple);
  		heap_endscan(pg_class_scan);
  	}
  	else
  	{
  		/* normal case, use syscache */
  		tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
  	}
  
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "could not find tuple for relation %u", relid);
  	rd_rel = (Form_pg_class) GETSTRUCT(tuple);
  
  	/* Should this be a more comprehensive test? */
  	Assert(rd_rel->relkind != RELKIND_PARTITIONED_INDEX);
  
  	/* Apply required updates, if any, to copied tuple */
  
  	dirty = false;
  	if (rd_rel->relhasindex != hasindex)
  	{
  		rd_rel->relhasindex = hasindex;
  		dirty = true;
  	}
  
  	if (reltuples >= 0)
  	{
  		BlockNumber relpages = IsYBRelation(rel) ? 0 : RelationGetNumberOfBlocks(rel);
  		BlockNumber relallvisible;
  
  		if (rd_rel->relkind != RELKIND_INDEX)
  			visibilitymap_count(rel, &relallvisible, NULL);
  		else					/* don't bother for indexes */
  			relallvisible = 0;
  
  		if (rd_rel->relpages != (int32) relpages)
  		{
  			rd_rel->relpages = (int32) relpages;
  			dirty = true;
  		}
  		if (rd_rel->reltuples != (float4) reltuples)
  		{
  			rd_rel->reltuples = (float4) reltuples;
  			dirty = true;
  		}
  		if (rd_rel->relallvisible != (int32) relallvisible)
  		{
  			rd_rel->relallvisible = (int32) relallvisible;
  			dirty = true;
  		}
  	}
  
  	/*
  	 * If anything changed, write out the tuple
  	 */
  	if (dirty)
  	{
  		heap_inplace_update(pg_class, tuple);
  		/* the above sends a cache inval message */
  	}
  	else
  	{
  		/* no need to change tuple, but force relcache inval anyway */
  		CacheInvalidateRelcacheByTuple(tuple);
  	}
  
  	heap_freetuple(tuple);
  
  	heap_close(pg_class, RowExclusiveLock);
  }
  
  
  /*
   * index_build - invoke access-method-specific index build procedure
   *
   * On entry, the index's catalog entries are valid, and its physical disk
   * file has been created but is empty.  We call the AM-specific build
   * procedure to fill in the index contents.  We then update the pg_class
   * entries of the index and heap relation as needed, using statistics
   * returned by ambuild as well as data passed by the caller.
   *
   * isprimary tells whether to mark the index as a primary-key index.
   * isreindex indicates we are recreating a previously-existing index.
   * parallel indicates if parallelism may be useful.
   *
   * Note: when reindexing an existing index, isprimary can be false even if
   * the index is a PK; it's already properly marked and need not be re-marked.
   *
   * Note: before Postgres 8.2, the passed-in heap and index Relations
   * were automatically closed by this routine.  This is no longer the case.
   * The caller opened 'em, and the caller should close 'em.
   */
  void
  index_build(Relation heapRelation,
  			Relation indexRelation,
  			IndexInfo *indexInfo,
  			bool isprimary,
  			bool isreindex,
  			bool parallel)
  {
  	IndexBuildResult *stats;
  	Oid			save_userid;
  	int			save_sec_context;
  	int			save_nestlevel;
  
  	/*
  	 * sanity checks
  	 */
  	Assert(RelationIsValid(indexRelation));
  	Assert(PointerIsValid(indexRelation->rd_amroutine));
  	Assert(PointerIsValid(indexRelation->rd_amroutine->ambuild));
  	Assert(PointerIsValid(indexRelation->rd_amroutine->ambuildempty));
  
  	/*
  	 * Determine worker process details for parallel CREATE INDEX.  Currently,
  	 * only btree has support for parallel builds.
  	 *
  	 * Note that planner considers parallel safety for us.
  	 */
  	if (parallel && IsNormalProcessingMode() &&
  		indexRelation->rd_rel->relam == BTREE_AM_OID)
  		indexInfo->ii_ParallelWorkers =
  			plan_create_index_workers(RelationGetRelid(heapRelation),
  									  RelationGetRelid(indexRelation));
  
  	if (indexInfo->ii_ParallelWorkers == 0)
  		ereport(DEBUG1,
  				(errmsg("building index \"%s\" on table \"%s\" serially",
  						RelationGetRelationName(indexRelation),
  						RelationGetRelationName(heapRelation))));
  	else
  		ereport(DEBUG1,
  				(errmsg_plural("building index \"%s\" on table \"%s\" with request for %d parallel worker",
  							   "building index \"%s\" on table \"%s\" with request for %d parallel workers",
  							   indexInfo->ii_ParallelWorkers,
  							   RelationGetRelationName(indexRelation),
  							   RelationGetRelationName(heapRelation),
  							   indexInfo->ii_ParallelWorkers)));
  
  	/*
  	 * Switch to the table owner's userid, so that any index functions are run
  	 * as that user.  Also lock down security-restricted operations and
  	 * arrange to make GUC variable changes local to this command.
  	 */
  	GetUserIdAndSecContext(&save_userid, &save_sec_context);
  	SetUserIdAndSecContext(heapRelation->rd_rel->relowner,
  						   save_sec_context | SECURITY_RESTRICTED_OPERATION);
  	save_nestlevel = NewGUCNestLevel();
  
  	/*
  	 * Call the access method's build procedure
  	 */
  	stats = indexRelation->rd_amroutine->ambuild(heapRelation, indexRelation,
  	                        indexInfo);
  	Assert(PointerIsValid(stats));
  
  	/*
  	 * If this is an unlogged index, we may need to write out an init fork for
  	 * it -- but we must first check whether one already exists.  If, for
  	 * example, an unlogged relation is truncated in the transaction that
  	 * created it, or truncated twice in a subsequent transaction, the
  	 * relfilenode won't change, and nothing needs to be done here.
  	 */
  	if (indexRelation->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
  		!smgrexists(indexRelation->rd_smgr, INIT_FORKNUM))
  	{
  		RelationOpenSmgr(indexRelation);
  		smgrcreate(indexRelation->rd_smgr, INIT_FORKNUM, false);
  		indexRelation->rd_amroutine->ambuildempty(indexRelation);
  	}
  
  	/*
  	 * If we found any potentially broken HOT chains, mark the index as not
  	 * being usable until the current transaction is below the event horizon.
  	 * See src/backend/access/heap/README.HOT for discussion.  Also set this
  	 * if early pruning/vacuuming is enabled for the heap relation.  While it
  	 * might become safe to use the index earlier based on actual cleanup
  	 * activity and other active transactions, the test for that would be much
  	 * more complex and would require some form of blocking, so keep it simple
  	 * and fast by just using the current transaction.
  	 *
  	 * However, when reindexing an existing index, we should do nothing here.
  	 * Any HOT chains that are broken with respect to the index must predate
  	 * the index's original creation, so there is no need to change the
  	 * index's usability horizon.  Moreover, we *must not* try to change the
  	 * index's pg_index entry while reindexing pg_index itself, and this
  	 * optimization nicely prevents that.  The more complex rules needed for a
  	 * reindex are handled separately after this function returns.
  	 *
  	 * We also need not set indcheckxmin during a concurrent index build,
  	 * because we won't set indisvalid true until all transactions that care
  	 * about the broken HOT chains or early pruning/vacuuming are gone.
  	 *
  	 * Therefore, this code path can only be taken during non-concurrent
  	 * CREATE INDEX.  Thus the fact that heap_update will set the pg_index
  	 * tuple's xmin doesn't matter, because that tuple was created in the
  	 * current transaction anyway.  That also means we don't need to worry
  	 * about any concurrent readers of the tuple; no other transaction can see
  	 * it yet.
  	 */
  	if ((indexInfo->ii_BrokenHotChain || EarlyPruningEnabled(heapRelation)) &&
  		!isreindex &&
  		!indexInfo->ii_Concurrent)
  	{
  		Oid			indexId = RelationGetRelid(indexRelation);
  		Relation	pg_index;
  		HeapTuple	indexTuple;
  		Form_pg_index indexForm;
  
  		pg_index = heap_open(IndexRelationId, RowExclusiveLock);
  
  		indexTuple = SearchSysCacheCopy1(INDEXRELID,
  										 ObjectIdGetDatum(indexId));
  		if (!HeapTupleIsValid(indexTuple))
  			elog(ERROR, "cache lookup failed for index %u", indexId);
  		indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
  
  		/* If it's a new index, indcheckxmin shouldn't be set ... */
  		Assert(!indexForm->indcheckxmin);
  
  		indexForm->indcheckxmin = true;
  		CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
  
  		heap_freetuple(indexTuple);
  		heap_close(pg_index, RowExclusiveLock);
  	}
  
  	/*
  	 * Update heap and index pg_class rows
  	 */
  	index_update_stats(heapRelation,
  					   true,
  					   stats->heap_tuples);
  
  	index_update_stats(indexRelation,
  					   false,
  					   stats->index_tuples);
  
  	/* Make the updated catalog row versions visible */
  	CommandCounterIncrement();
  
  	/*
  	 * If it's for an exclusion constraint, make a second pass over the heap
  	 * to verify that the constraint is satisfied.  We must not do this until
  	 * the index is fully valid.  (Broken HOT chains shouldn't matter, though;
  	 * see comments for IndexCheckExclusion.)
  	 */
  	if (indexInfo->ii_ExclusionOps != NULL)
  		IndexCheckExclusion(heapRelation, indexRelation, indexInfo);
  
  	/* Roll back any GUC changes executed by index functions */
  	AtEOXact_GUC(false, save_nestlevel);
  
  	/* Restore userid and security context */
  	SetUserIdAndSecContext(save_userid, save_sec_context);
  }
  
  /*
   * index_backfill - invoke access-method-specific index backfill procedure
   *
   * This is mainly a copy of index_build.  index_build is used for
   * non-multi-stage index creation; index_backfill is used for multi-stage index
   * creation.
   */
  void
  index_backfill(Relation heapRelation,
  			   Relation indexRelation,
  			   IndexInfo *indexInfo,
  			   bool isprimary,
  			   uint64_t *read_time,
  			   RowBounds *row_bounds)
  {
  	Oid			save_userid;
  	int			save_sec_context;
  	int			save_nestlevel;
  
  	/*
  	 * sanity checks
  	 */
  	Assert(RelationIsValid(indexRelation));
  	Assert(PointerIsValid(indexRelation->rd_amroutine));
  	Assert(PointerIsValid(indexRelation->rd_amroutine->yb_ambackfill));
  
  	ereport(DEBUG1,
  			(errmsg("backfilling index \"%s\" on table \"%s\"",
  					RelationGetRelationName(indexRelation),
  					RelationGetRelationName(heapRelation))));
  
  	/*
  	 * Switch to the table owner's userid, so that any index functions are run
  	 * as that user.  Also lock down security-restricted operations and
  	 * arrange to make GUC variable changes local to this command.
  	 */
  	GetUserIdAndSecContext(&save_userid, &save_sec_context);
  	SetUserIdAndSecContext(heapRelation->rd_rel->relowner,
  						   save_sec_context | SECURITY_RESTRICTED_OPERATION);
  	save_nestlevel = NewGUCNestLevel();
  
  	/*
  	 * Call the access method's build procedure
  	 */
  	indexRelation->rd_amroutine->yb_ambackfill(heapRelation,
  											   indexRelation,
  											   indexInfo,
  											   read_time,
  											   row_bounds);
  
  	/*
  	 * I don't think we should be backfilling unlogged indexes.
  	 */
  	Assert(indexRelation->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED);
  
  	/*
  	 * Update heap and index pg_class rows
  	 * TODO(jason): properly update reltuples.  They can't be set here because
  	 * this backfill func is called for each backfill chunk request from
  	 * master, and we need some way to sum up the tuple numbers.  We also don't
  	 * even collect stats properly for heapRelation anyway, at the moment.
  	 */
  	index_update_stats(heapRelation,
  					   true,
  					   -1);
  
  	index_update_stats(indexRelation,
  					   false,
  					   -1);
  
  	/* Make the updated catalog row versions visible */
  	CommandCounterIncrement();
  
  	/* Roll back any GUC changes executed by index functions */
  	AtEOXact_GUC(false, save_nestlevel);
  
  	/* Restore userid and security context */
  	SetUserIdAndSecContext(save_userid, save_sec_context);
  }
  
  
  /*
   * IndexBuildHeapScan - scan the heap relation to find tuples to be indexed
   *
   * This is called back from an access-method-specific index build procedure
   * after the AM has done whatever setup it needs.  The parent heap relation
   * is scanned to find tuples that should be entered into the index.  Each
   * such tuple is passed to the AM's callback routine, which does the right
   * things to add it to the new index.  After we return, the AM's index
   * build procedure does whatever cleanup it needs.
   *
   * The total count of live heap tuples is returned.  This is for updating
   * pg_class statistics.  (It's annoying not to be able to do that here, but we
   * want to merge that update with others; see index_update_stats.)  Note that
   * the index AM itself must keep track of the number of index tuples; we don't
   * do so here because the AM might reject some of the tuples for its own
   * reasons, such as being unable to store NULLs.
   *
   * A side effect is to set indexInfo->ii_BrokenHotChain to true if we detect
   * any potentially broken HOT chains.  Currently, we set this if there are
   * any RECENTLY_DEAD or DELETE_IN_PROGRESS entries in a HOT chain, without
   * trying very hard to detect whether they're really incompatible with the
   * chain tip.
   */
  double
  IndexBuildHeapScan(Relation heapRelation,
  				   Relation indexRelation,
  				   IndexInfo *indexInfo,
  				   bool allow_sync,
  				   IndexBuildCallback callback,
  				   void *callback_state,
  				   HeapScanDesc scan)
  {
  	return IndexBuildHeapRangeScan(heapRelation, indexRelation,
  								   indexInfo, allow_sync,
  								   false,
  								   0, InvalidBlockNumber,
  								   callback, callback_state, scan);
  }
  
  double
  IndexBuildHeapRangeScan(Relation heapRelation,
  						Relation indexRelation,
  						IndexInfo *indexInfo,
  						bool allow_sync,
  						bool anyvisible,
  						BlockNumber start_blockno,
  						BlockNumber numblocks,
  						IndexBuildCallback callback,
  						void *callback_state,
  						HeapScanDesc scan)
  {
  	return IndexBuildHeapRangeScanInternal(heapRelation,
  										   indexRelation,
  										   indexInfo,
  										   allow_sync,
  										   anyvisible,
  										   start_blockno,
  										   numblocks,
  										   callback,
  										   callback_state,
  										   scan,
  										   NULL /* read_time */,
  										   NULL /* row_bounds */);
  }
  
  double
  IndexBackfillHeapRangeScan(Relation heapRelation,
  						   Relation indexRelation,
  						   IndexInfo *indexInfo,
  						   IndexBuildCallback callback,
  						   void *callback_state,
  						   uint64_t *read_time,
  						   RowBounds *row_bounds)
  {
  	return IndexBuildHeapRangeScanInternal(heapRelation,
  										   indexRelation,
  										   indexInfo,
  										   true /* allow_sync */,
  										   false /* any_visible */,
  										   0 /* start_blockno */,
  										   InvalidBlockNumber /* num_blocks */,
  										   callback,
  										   callback_state,
  										   NULL /* scan */,
  										   read_time,
  										   row_bounds);
  }
  
  /*
   * As above, except that instead of scanning the complete heap, only the given
   * number of blocks are scanned.  Scan to end-of-rel can be signalled by
   * passing InvalidBlockNumber as numblocks.  Note that restricting the range
   * to scan cannot be done when requesting syncscan.
   *
   * When "anyvisible" mode is requested, all tuples visible to any transaction
   * are indexed and counted as live, including those inserted or deleted by
   * transactions that are still in progress.
   */
  static double
  IndexBuildHeapRangeScanInternal(Relation heapRelation,
  								Relation indexRelation,
  								IndexInfo *indexInfo,
  								bool allow_sync,
  								bool anyvisible,
  								BlockNumber start_blockno,
  								BlockNumber numblocks,
  								IndexBuildCallback callback,
  								void *callback_state,
  								HeapScanDesc scan,
  								uint64_t *read_time,
  								RowBounds *row_bounds)
  {
  	bool		is_system_catalog;
  	bool		checking_uniqueness;
  	HeapTuple	heapTuple;
  	Datum		values[INDEX_MAX_KEYS];
  	bool		isnull[INDEX_MAX_KEYS];
  	double		reltuples;
  	ExprState  *predicate;
  	TupleTableSlot *slot;
  	EState	   *estate;
  	ExprContext *econtext;
  	Snapshot	snapshot;
  	bool		need_unregister_snapshot = false;
  	TransactionId OldestXmin;
  	BlockNumber root_blkno = InvalidBlockNumber;
  	OffsetNumber root_offsets[MaxHeapTuplesPerPage];
  	MemoryContext oldcontext = GetCurrentMemoryContext();
  
  	/*
  	 * sanity checks
  	 */
  	Assert(OidIsValid(indexRelation->rd_rel->relam));
  
  	/* Remember if it's a system catalog */
  	is_system_catalog = IsSystemRelation(heapRelation);
  
  	/* See whether we're verifying uniqueness/exclusion properties */
  	checking_uniqueness = (indexInfo->ii_Unique ||
  						   indexInfo->ii_ExclusionOps != NULL);
  
  	/*
  	 * "Any visible" mode is not compatible with uniqueness checks; make sure
  	 * only one of those is requested.
  	 */
  	Assert(!(anyvisible && checking_uniqueness));
  
  	/*
  	 * Need an EState for evaluation of index expressions and partial-index
  	 * predicates.  Also a slot to hold the current tuple.
  	 */
  	estate = CreateExecutorState();
  	econtext = GetPerTupleExprContext(estate);
  	slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation));
  
  	/*
  	 * Set some exec params.
  	 */
  	YBCPgExecParameters *exec_params = &estate->yb_exec_params;
  	if (read_time)
  		exec_params->read_time = *read_time;
  	if (row_bounds)
  		exec_params->partition_key = pstrdup(row_bounds->partition_key);
  
  	/* Arrange for econtext's scan tuple to be the tuple under test */
  	econtext->ecxt_scantuple = slot;
  
  	/* Set up execution state for predicate, if any. */
  	predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate);
  
  	/*
  	 * Prepare for scan of the base relation.  In a normal index build, we use
  	 * SnapshotAny because we must retrieve all tuples and do our own time
  	 * qual checks (because we have to index RECENTLY_DEAD tuples). In a
  	 * concurrent build, or during bootstrap, we take a regular MVCC snapshot
  	 * and index whatever's live according to that.
  	 */
  	OldestXmin = InvalidTransactionId;
  
  	/* okay to ignore lazy VACUUMs here */
  	if (!IsBootstrapProcessingMode() && !indexInfo->ii_Concurrent)
  		OldestXmin = GetOldestXmin(heapRelation, PROCARRAY_FLAGS_VACUUM);
  
  	if (!scan)
  	{
  		/*
  		 * Serial index build.
  		 *
  		 * Must begin our own heap scan in this case.  We may also need to
  		 * register a snapshot whose lifetime is under our direct control.
  		 */
  		if (!TransactionIdIsValid(OldestXmin))
  		{
  			snapshot = RegisterSnapshot(GetTransactionSnapshot());
  			need_unregister_snapshot = true;
  		}
  		else
  			snapshot = SnapshotAny;
  
  		scan = heap_beginscan_strat(heapRelation,	/* relation */
  									snapshot,	/* snapshot */
  									0,	/* number of keys */
  									NULL,	/* scan key */
  									true,	/* buffer access strategy OK */
  									allow_sync);	/* syncscan OK? */
  		if (IsYBRelation(heapRelation))
  			scan->ybscan->exec_params = exec_params;
  	}
  	else
  	{
  		/*
  		 * Parallel index build.
  		 *
  		 * Parallel case never registers/unregisters own snapshot.  Snapshot
  		 * is taken from parallel heap scan, and is SnapshotAny or an MVCC
  		 * snapshot, based on same criteria as serial case.
  		 */
  		Assert(!IsBootstrapProcessingMode());
  		Assert(allow_sync);
  		snapshot = scan->rs_snapshot;
  	}
  
  	/*
  	 * Must call GetOldestXmin() with SnapshotAny.  Should never call
  	 * GetOldestXmin() with MVCC snapshot. (It's especially worth checking
  	 * this for parallel builds, since yb_ambackfill routines that support
  	 * parallel builds must work these details out for themselves.)
  	 */
  	Assert(snapshot == SnapshotAny || IsMVCCSnapshot(snapshot));
  	Assert(snapshot == SnapshotAny ? TransactionIdIsValid(OldestXmin) :
  		   !TransactionIdIsValid(OldestXmin));
  	Assert(snapshot == SnapshotAny || !anyvisible);
  
  	/* set our scan endpoints */
  	if (!allow_sync)
  		heap_setscanlimits(scan, start_blockno, numblocks);
  	else
  	{
  		/* syncscan can only be requested on whole relation */
  		Assert(start_blockno == 0);
  		Assert(numblocks == InvalidBlockNumber);
  	}
  
  	reltuples = 0;
  
  	if (IsYBRelation(indexRelation))
  		MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
  
  	/*
  	 * Scan all tuples in the base relation.
  	 */
  	while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
  	{
  		bool    tupleIsAlive;
  
  		CHECK_FOR_INTERRUPTS();
  
  		/*
  		 * Skip handling of HOT-chained tuples which does not apply to YugaByte-based
  		 * tables.
  		 */
  		if (!IsYBRelation(heapRelation))
  		{
  			/*
  			 * When dealing with a HOT-chain of updated tuples, we want to index
  			 * the values of the live tuple (if any), but index it under the TID
  			 * of the chain's root tuple.  This approach is necessary to preserve
  			 * the HOT-chain structure in the heap. So we need to be able to find
  			 * the root item offset for every tuple that's in a HOT-chain.  When
  			 * first reaching a new page of the relation, call
  			 * heap_get_root_tuples() to build a map of root item offsets on the
  			 * page.
  			 *
  			 * It might look unsafe to use this information across buffer
  			 * lock/unlock.  However, we hold ShareLock on the table so no
  			 * ordinary insert/update/delete should occur; and we hold pin on the
  			 * buffer continuously while visiting the page, so no pruning
  			 * operation can occur either.
  			 *
  			 * Also, although our opinions about tuple liveness could change while
  			 * we scan the page (due to concurrent transaction commits/aborts),
  			 * the chain root locations won't, so this info doesn't need to be
  			 * rebuilt after waiting for another transaction.
  			 *
  			 * Note the implied assumption that there is no more than one live
  			 * tuple per HOT-chain --- else we could create more than one index
  			 * entry pointing to the same root tuple.
  			 */
  			if (scan->rs_cblock != root_blkno)
  			{
  				Page    page = BufferGetPage(scan->rs_cbuf);
  
  				LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
  				heap_get_root_tuples(page, root_offsets);
  				LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
  
  				root_blkno = scan->rs_cblock;
  			}
  
  			if (snapshot == SnapshotAny)
  			{
  				/* do our own time qual check */
  				bool    indexIt;
  				TransactionId xwait;
  
  				recheck:
  
  				/*
  				 * We could possibly get away with not locking the buffer here,
  				 * since caller should hold ShareLock on the relation, but let's
  				 * be conservative about it.  (This remark is still correct even
  				 * with HOT-pruning: our pin on the buffer prevents pruning.)
  				 */
  				LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
  
  				/*
  				 * The criteria for counting a tuple as live in this block need to
  				 * match what analyze.c's acquire_sample_rows() does, otherwise
  				 * CREATE INDEX and ANALYZE may produce wildly different reltuples
  				 * values, e.g. when there are many recently-dead tuples.
  				 */
  				switch (HeapTupleSatisfiesVacuum(heapTuple, OldestXmin,
  												scan->rs_cbuf))
  				{
  					case HEAPTUPLE_DEAD:
  						/* Definitely dead, we can ignore it */
  						indexIt = false;
  						tupleIsAlive = false;
  						break;
  					case HEAPTUPLE_LIVE:
  						/* Normal case, index and unique-check it */
  						indexIt = true;
  						tupleIsAlive = true;
  						/* Count it as live, too */
  						reltuples += 1;
  						break;
  					case HEAPTUPLE_RECENTLY_DEAD:
  						/*
  						 * If tuple is recently deleted then we must index it
  						 * anyway to preserve MVCC semantics.  (Pre-existing
  						 * transactions could try to use the index after we finish
  						 * building it, and may need to see such tuples.)
  						 *
  						 * However, if it was HOT-updated then we must only index
  						 * the live tuple at the end of the HOT-chain.  Since this
  						 * breaks semantics for pre-existing snapshots, mark the
  						 * index as unusable for them.
  						 *
  						 * We don't count recently-dead tuples in reltuples, even
  						 * if we index them; see acquire_sample_rows().
  						 */
  						if (HeapTupleIsHotUpdated(heapTuple))
  						{
  							indexIt = false;
  							/* mark the index as unsafe for old snapshots */
  							indexInfo->ii_BrokenHotChain = true;
  						}
  						else
  							indexIt = true;
  						/* In any case, exclude the tuple from unique-checking */
  						tupleIsAlive = false;
  						break;
  					case HEAPTUPLE_INSERT_IN_PROGRESS:
  						/*
  						 * In "anyvisible" mode, this tuple is visible and we
  						 * don't need any further checks.
  						 */
  						if (anyvisible)
  						{
  							indexIt = true;
  							tupleIsAlive = true;
  							reltuples += 1;
  							break;
  						}
  
  						/*
  						 * Since caller should hold ShareLock or better, normally
  						 * the only way to see this is if it was inserted earlier
  						 * in our own transaction.  However, it can happen in
  						 * system catalogs, since we tend to release write lock
  						 * before commit there.  Give a warning if neither case
  						 * applies.
  						 */
  						xwait = HeapTupleHeaderGetXmin(heapTuple->t_data);
  						if (!TransactionIdIsCurrentTransactionId(xwait))
  						{
  							if (!is_system_catalog)
  								elog(WARNING, "concurrent insert in progress within table \"%s\"",
  									RelationGetRelationName(heapRelation));
  
  							/*
  							 * If we are performing uniqueness checks, indexing
  							 * such a tuple could lead to a bogus uniqueness
  							 * failure.  In that case we wait for the inserting
  							 * transaction to finish and check again.
  							 */
  							if (checking_uniqueness)
  							{
  								/*
  								 * Must drop the lock on the buffer before we wait
  								 */
  								LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
  								XactLockTableWait(xwait, heapRelation,
  												&heapTuple->t_self,
  												XLTW_InsertIndexUnique);
  								CHECK_FOR_INTERRUPTS();
  								goto recheck;
  							}
  							else
  							{
  								/*
  								 * For consistency with acquire_sample_rows(), count
  								 * HEAPTUPLE_INSERT_IN_PROGRESS tuples as live only
  								 * when inserted by our own transaction.
  								 */
  								reltuples += 1;
  							}
  						}
  
  						/*
  						 * We must index such tuples, since if the index build
  						 * commits then they're good.
  						 */
  						indexIt = true;
  						tupleIsAlive = true;
  						break;
  					case HEAPTUPLE_DELETE_IN_PROGRESS:
  
  						/*
  						 * As with INSERT_IN_PROGRESS case, this is unexpected
  						 * unless it's our own deletion or a system catalog; but
  						 * in anyvisible mode, this tuple is visible.
  						 */
  						if (anyvisible)
  						{
  							indexIt = true;
  							tupleIsAlive = false;
  							reltuples += 1;
  							break;
  						}
  
  						xwait = HeapTupleHeaderGetUpdateXid(heapTuple->t_data);
  						if (!TransactionIdIsCurrentTransactionId(xwait))
  						{
  							if (!is_system_catalog)
  								elog(WARNING, "concurrent delete in progress within table \"%s\"",
  									RelationGetRelationName(heapRelation));
  
  							/*
  							 * If we are performing uniqueness checks, assuming
  							 * the tuple is dead could lead to missing a
  							 * uniqueness violation.  In that case we wait for the
  							 * deleting transaction to finish and check again.
  							 *
  							 * Also, if it's a HOT-updated tuple, we should not
  							 * index it but rather the live tuple at the end of
  							 * the HOT-chain.  However, the deleting transaction
  							 * could abort, possibly leaving this tuple as live
  							 * after all, in which case it has to be indexed. The
  							 * only way to know what to do is to wait for the
  							 * deleting transaction to finish and check again.
  							 */
  							if (checking_uniqueness ||
  								HeapTupleIsHotUpdated(heapTuple))
  							{
  								/*
  								 * Must drop the lock on the buffer before we wait
  								 */
  								LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
  								XactLockTableWait(xwait, heapRelation,
  												&heapTuple->t_self,
  												XLTW_InsertIndexUnique);
  								CHECK_FOR_INTERRUPTS();
  								goto recheck;
  							}
  
  							/*
  							 * Otherwise index it but don't check for uniqueness,
  							 * the same as a RECENTLY_DEAD tuple.
  							 */
  							indexIt = true;
  
  							/*
  							 * Count HEAPTUPLE_DELETE_IN_PROGRESS tuples as live,
  							 * if they were not deleted by the current
  							 * transaction.  That's what acquire_sample_rows()
  							 * does, and we want the behavior to be consistent.
  							 */
  							reltuples += 1;
  						}
  						else if (HeapTupleIsHotUpdated(heapTuple))
  						{
  							/*
  							 * It's a HOT-updated tuple deleted by our own xact.
  							 * We can assume the deletion will commit (else the
  							 * index contents don't matter), so treat the same as
  							 * RECENTLY_DEAD HOT-updated tuples.
  							 */
  							indexIt = false;
  							/* mark the index as unsafe for old snapshots */
  							indexInfo->ii_BrokenHotChain = true;
  						}
  						else
  						{
  							/*
  							 * It's a regular tuple deleted by our own xact. Index
  							 * it, but don't check for uniqueness nor count in
  							 * reltuples, the same as a RECENTLY_DEAD tuple.
  							 */
  							indexIt = true;
  						}
  						/* In any case, exclude the tuple from unique-checking */
  						tupleIsAlive = false;
  						break;
  					default:
  						elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
  						indexIt = tupleIsAlive = false; /* keep compiler quiet */
  						break;
  				}
  
  				LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
  
  				if (!indexIt)
  					continue;
  			}
  			else
  			{
  				/* heap_getnext did the time qual check */
  				tupleIsAlive = true;
  				reltuples += 1;
  			}
  		}
  		else
  		{
  			/* In YugaByte mode DocDB will only send live tuples. */
  			tupleIsAlive = true;
  		}
  
  		if (!IsYBRelation(indexRelation))
  			MemoryContextReset(econtext->ecxt_per_tuple_memory);
  
  		/* Set up for predicate or expression evaluation */
  		ExecStoreHeapTuple(heapTuple, slot, false);
  
  		/*
  		 * In a partial index, discard tuples that don't satisfy the
  		 * predicate.
  		 */
  		if (predicate != NULL)
  		{
  			if (!ExecQual(predicate, econtext))
  				continue;
  		}
  
  		/*
  		 * For the current heap tuple, extract all the attributes we use in
  		 * this index, and note which are null.  This also performs evaluation
  		 * of any expressions needed.
  		 */
  		FormIndexDatum(indexInfo,
  					   slot,
  					   estate,
  					   values,
  					   isnull);
  
  		/*
  		 * You'd think we should go ahead and build the index tuple here, but
  		 * some index AMs want to do further processing on the data first.  So
  		 * pass the values[] and isnull[] arrays, instead.
  		 * This is not needed and should be skipped for YugaByte enabled tables.
  		 */
  
  		if (!IsYugaByteEnabled() && HeapTupleIsHeapOnly(heapTuple))
  		{
  			/*
  			 * For a heap-only tuple, pretend its TID is that of the root. See
  			 * src/backend/access/heap/README.HOT for discussion.
  			 */
  			HeapTupleData rootTuple;
  			OffsetNumber offnum;
  
  			rootTuple = *heapTuple;
  			offnum = ItemPointerGetOffsetNumber(&heapTuple->t_self);
  
  			if (!OffsetNumberIsValid(root_offsets[offnum - 1]))
  				ereport(ERROR,
  						(errcode(ERRCODE_DATA_CORRUPTED),
  						 errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
  										 ItemPointerGetBlockNumber(&heapTuple->t_self),
  										 offnum,
  										 RelationGetRelationName(heapRelation))));
  
  			ItemPointerSetOffsetNumber(&rootTuple.t_self,
  									   root_offsets[offnum - 1]);
  
  			/* Call the AM's callback routine to process the tuple */
  			callback(indexRelation, &rootTuple, values, isnull, tupleIsAlive,
  					 callback_state);
  		}
  		else
  		{
  			/* Call the AM's callback routine to process the tuple */
  			callback(indexRelation, heapTuple, values, isnull, tupleIsAlive,
  					 callback_state);
  		}
  	
  		if (IsYBRelation(indexRelation))
  			MemoryContextReset(econtext->ecxt_per_tuple_memory);
  	}
  
  	if (IsYBRelation(indexRelation))
  		MemoryContextSwitchTo(oldcontext);
  
  	heap_endscan(scan);
  
  	/* we can now forget our snapshot, if set and registered by us */
  	if (need_unregister_snapshot)
  		UnregisterSnapshot(snapshot);
  
  	ExecDropSingleTupleTableSlot(slot);
  
  	FreeExecutorState(estate);
  
  	/* These may have been pointing to the now-gone estate */
  	indexInfo->ii_ExpressionsState = NIL;
  	indexInfo->ii_PredicateState = NULL;
  
  	return reltuples;
  }
  
  
  /*
   * IndexCheckExclusion - verify that a new exclusion constraint is satisfied
   *
   * When creating an exclusion constraint, we first build the index normally
   * and then rescan the heap to check for conflicts.  We assume that we only
   * need to validate tuples that are live according to an up-to-date snapshot,
   * and that these were correctly indexed even in the presence of broken HOT
   * chains.  This should be OK since we are holding at least ShareLock on the
   * table, meaning there can be no uncommitted updates from other transactions.
   * (Note: that wouldn't necessarily work for system catalogs, since many
   * operations release write lock early on the system catalogs.)
   */
  static void
  IndexCheckExclusion(Relation heapRelation,
  					Relation indexRelation,
  					IndexInfo *indexInfo)
  {
  	HeapScanDesc scan;
  	HeapTuple	heapTuple;
  	Datum		values[INDEX_MAX_KEYS];
  	bool		isnull[INDEX_MAX_KEYS];
  	ExprState  *predicate;
  	TupleTableSlot *slot;
  	EState	   *estate;
  	ExprContext *econtext;
  	Snapshot	snapshot;
  
  	/*
  	 * If we are reindexing the target index, mark it as no longer being
  	 * reindexed, to forestall an Assert in index_beginscan when we try to use
  	 * the index for probes.  This is OK because the index is now fully valid.
  	 */
  	if (ReindexIsCurrentlyProcessingIndex(RelationGetRelid(indexRelation)))
  		ResetReindexProcessing();
  
  	/*
  	 * Need an EState for evaluation of index expressions and partial-index
  	 * predicates.  Also a slot to hold the current tuple.
  	 */
  	estate = CreateExecutorState();
  	econtext = GetPerTupleExprContext(estate);
  	slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation));
  
  	/* Arrange for econtext's scan tuple to be the tuple under test */
  	econtext->ecxt_scantuple = slot;
  
  	/* Set up execution state for predicate, if any. */
  	predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate);
  
  	/*
  	 * Scan all live tuples in the base relation.
  	 */
  	snapshot = RegisterSnapshot(GetLatestSnapshot());
  	scan = heap_beginscan_strat(heapRelation,	/* relation */
  								snapshot,	/* snapshot */
  								0,	/* number of keys */
  								NULL,	/* scan key */
  								true,	/* buffer access strategy OK */
  								true);	/* syncscan OK */
  
  	while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
  	{
  		CHECK_FOR_INTERRUPTS();
  
  		MemoryContextReset(econtext->ecxt_per_tuple_memory);
  
  		/* Set up for predicate or expression evaluation */
  		ExecStoreHeapTuple(heapTuple, slot, false);
  
  		/*
  		 * In a partial index, ignore tuples that don't satisfy the predicate.
  		 */
  		if (predicate != NULL)
  		{
  			if (!ExecQual(predicate, econtext))
  				continue;
  		}
  
  		/*
  		 * Extract index column values, including computing expressions.
  		 */
  		FormIndexDatum(indexInfo,
  					   slot,
  					   estate,
  					   values,
  					   isnull);
  
  		/*
  		 * Check that this tuple has no conflicts.
  		 */
  		check_exclusion_constraint(heapRelation,
  								   indexRelation, indexInfo,
  								   &(heapTuple->t_self), values, isnull,
  								   estate, true);
  	}
  
  	heap_endscan(scan);
  	UnregisterSnapshot(snapshot);
  
  	ExecDropSingleTupleTableSlot(slot);
  
  	FreeExecutorState(estate);
  
  	/* These may have been pointing to the now-gone estate */
  	indexInfo->ii_ExpressionsState = NIL;
  	indexInfo->ii_PredicateState = NULL;
  }
  
  
  /*
   * validate_index - support code for concurrent index builds
   *
   * We do a concurrent index build by first inserting the catalog entry for the
   * index via index_create(), marking it not indisready and not indisvalid.
   * Then we commit our transaction and start a new one, then we wait for all
   * transactions that could have been modifying the table to terminate.  Now
   * we know that any subsequently-started transactions will see the index and
   * honor its constraints on HOT updates; so while existing HOT-chains might
   * be broken with respect to the index, no currently live tuple will have an
   * incompatible HOT update done to it.  We now build the index normally via
   * index_build(), while holding a weak lock that allows concurrent
   * insert/update/delete.  Also, we index only tuples that are valid
   * as of the start of the scan (see IndexBuildHeapScan), whereas a normal
   * build takes care to include recently-dead tuples.  This is OK because
   * we won't mark the index valid until all transactions that might be able
   * to see those tuples are gone.  The reason for doing that is to avoid
   * bogus unique-index failures due to concurrent UPDATEs (we might see
   * different versions of the same row as being valid when we pass over them,
   * if we used HeapTupleSatisfiesVacuum).  This leaves us with an index that
   * does not contain any tuples added to the table while we built the index.
   *
   * Next, we mark the index "indisready" (but still not "indisvalid") and
   * commit the second transaction and start a third.  Again we wait for all
   * transactions that could have been modifying the table to terminate.  Now
   * we know that any subsequently-started transactions will see the index and
   * insert their new tuples into it.  We then take a new reference snapshot
   * which is passed to validate_index().  Any tuples that are valid according
   * to this snap, but are not in the index, must be added to the index.
   * (Any tuples committed live after the snap will be inserted into the
   * index by their originating transaction.  Any tuples committed dead before
   * the snap need not be indexed, because we will wait out all transactions
   * that might care about them before we mark the index valid.)
   *
   * validate_index() works by first gathering all the TIDs currently in the
   * index, using a bulkdelete callback that just stores the TIDs and doesn't
   * ever say "delete it".  (This should be faster than a plain indexscan;
   * also, not all index AMs support full-index indexscan.)  Then we sort the
   * TIDs, and finally scan the table doing a "merge join" against the TID list
   * to see which tuples are missing from the index.  Thus we will ensure that
   * all tuples valid according to the reference snapshot are in the index.
   *
   * Building a unique index this way is tricky: we might try to insert a
   * tuple that is already dead or is in process of being deleted, and we
   * mustn't have a uniqueness failure against an updated version of the same
   * row.  We could try to check the tuple to see if it's already dead and tell
   * index_insert() not to do the uniqueness check, but that still leaves us
   * with a race condition against an in-progress update.  To handle that,
   * we expect the index AM to recheck liveness of the to-be-inserted tuple
   * before it declares a uniqueness error.
   *
   * After completing validate_index(), we wait until all transactions that
   * were alive at the time of the reference snapshot are gone; this is
   * necessary to be sure there are none left with a transaction snapshot
   * older than the reference (and hence possibly able to see tuples we did
   * not index).  Then we mark the index "indisvalid" and commit.  Subsequent
   * transactions will be able to use it for queries.
   *
   * Doing two full table scans is a brute-force strategy.  We could try to be
   * cleverer, eg storing new tuples in a special area of the table (perhaps
   * making the table append-only by setting use_fsm).  However that would
   * add yet more locking issues.
   */
  void
  validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
  {
  	Relation	heapRelation,
  				indexRelation;
  	IndexInfo  *indexInfo;
  	IndexVacuumInfo ivinfo;
  	v_i_state	state;
  	Oid			save_userid;
  	int			save_sec_context;
  	int			save_nestlevel;
  
  	/* Open and lock the parent heap relation */
  	heapRelation = heap_open(heapId, ShareUpdateExclusiveLock);
  	/* And the target index relation */
  	indexRelation = index_open(indexId, RowExclusiveLock);
  
  	/*
  	 * Fetch info needed for index_insert.  (You might think this should be
  	 * passed in from DefineIndex, but its copy is long gone due to having
  	 * been built in a previous transaction.)
  	 */
  	indexInfo = BuildIndexInfo(indexRelation);
  
  	/* mark build is concurrent just for consistency */
  	indexInfo->ii_Concurrent = true;
  
  	/*
  	 * Switch to the table owner's userid, so that any index functions are run
  	 * as that user.  Also lock down security-restricted operations and
  	 * arrange to make GUC variable changes local to this command.
  	 */
  	GetUserIdAndSecContext(&save_userid, &save_sec_context);
  	SetUserIdAndSecContext(heapRelation->rd_rel->relowner,
  						   save_sec_context | SECURITY_RESTRICTED_OPERATION);
  	save_nestlevel = NewGUCNestLevel();
  
  	/*
  	 * Scan the index and gather up all the TIDs into a tuplesort object.
  	 */
  	ivinfo.index = indexRelation;
  	ivinfo.analyze_only = false;
  	ivinfo.estimated_count = true;
  	ivinfo.message_level = DEBUG2;
  	ivinfo.num_heap_tuples = heapRelation->rd_rel->reltuples;
  	ivinfo.strategy = NULL;
  
  	/*
  	 * Encode TIDs as int8 values for the sort, rather than directly sorting
  	 * item pointers.  This can be significantly faster, primarily because TID
  	 * is a pass-by-reference type on all platforms, whereas int8 is
  	 * pass-by-value on most platforms.
  	 */
  	state.tuplesort = tuplesort_begin_datum(INT8OID, Int8LessOperator,
  											InvalidOid, false,
  											maintenance_work_mem,
  											NULL, false);
  	state.htups = state.itups = state.tups_inserted = 0;
  
  	(void) index_bulk_delete(&ivinfo, NULL,
  							 validate_index_callback, (void *) &state);
  
  	/* Execute the sort */
  	tuplesort_performsort(state.tuplesort);
  
  	/*
  	 * Now scan the heap and "merge" it with the index
  	 */
  	validate_index_heapscan(heapRelation,
  							indexRelation,
  							indexInfo,
  							snapshot,
  							&state);
  
  	/* Done with tuplesort object */
  	tuplesort_end(state.tuplesort);
  
  	elog(DEBUG2,
  		 "validate_index found %.0f heap tuples, %.0f index tuples; inserted %.0f missing tuples",
  		 state.htups, state.itups, state.tups_inserted);
  
  	/* Roll back any GUC changes executed by index functions */
  	AtEOXact_GUC(false, save_nestlevel);
  
  	/* Restore userid and security context */
  	SetUserIdAndSecContext(save_userid, save_sec_context);
  
  	/* Close rels, but keep locks */
  	index_close(indexRelation, NoLock);
  	heap_close(heapRelation, NoLock);
  }
  
  /*
   * itemptr_encode - Encode ItemPointer as int64/int8
   *
   * This representation must produce values encoded as int64 that sort in the
   * same order as their corresponding original TID values would (using the
   * default int8 opclass to produce a result equivalent to the default TID
   * opclass).
   *
   * As noted in validate_index(), this can be significantly faster.
   */
  static inline int64
  itemptr_encode(ItemPointer itemptr)
  {
  	BlockNumber block = ItemPointerGetBlockNumber(itemptr);
  	OffsetNumber offset = ItemPointerGetOffsetNumber(itemptr);
  	int64		encoded;
  
  	/*
  	 * Use the 16 least significant bits for the offset.  32 adjacent bits are
  	 * used for the block number.  Since remaining bits are unused, there
  	 * cannot be negative encoded values (We assume a two's complement
  	 * representation).
  	 */
  	encoded = ((uint64) block << 16) | (uint16) offset;
  
  	return encoded;
  }
  
  /*
   * itemptr_decode - Decode int64/int8 representation back to ItemPointer
   */
  static inline void
  itemptr_decode(ItemPointer itemptr, int64 encoded)
  {
  	BlockNumber block = (BlockNumber) (encoded >> 16);
  	OffsetNumber offset = (OffsetNumber) (encoded & 0xFFFF);
  
  	ItemPointerSet(itemptr, block, offset);
  }
  
  /*
   * validate_index_callback - bulkdelete callback to collect the index TIDs
   */
  static bool
  validate_index_callback(ItemPointer itemptr, void *opaque)
  {
  	v_i_state  *state = (v_i_state *) opaque;
  	int64		encoded = itemptr_encode(itemptr);
  
  	tuplesort_putdatum(state->tuplesort, Int64GetDatum(encoded), false);
  	state->itups += 1;
  	return false;				/* never actually delete anything */
  }
  
  /*
   * validate_index_heapscan - second table scan for concurrent index build
   *
   * This has much code in common with IndexBuildHeapScan, but it's enough
   * different that it seems cleaner to have two routines not one.
   */
  static void
  validate_index_heapscan(Relation heapRelation,
  						Relation indexRelation,
  						IndexInfo *indexInfo,
  						Snapshot snapshot,
  						v_i_state *state)
  {
  	HeapScanDesc scan;
  	HeapTuple	heapTuple;
  	Datum		values[INDEX_MAX_KEYS];
  	bool		isnull[INDEX_MAX_KEYS];
  	ExprState  *predicate;
  	TupleTableSlot *slot;
  	EState	   *estate;
  	ExprContext *econtext;
  	BlockNumber root_blkno = InvalidBlockNumber;
  	OffsetNumber root_offsets[MaxHeapTuplesPerPage];
  	bool		in_index[MaxHeapTuplesPerPage];
  
  	/* state variables for the merge */
  	ItemPointer indexcursor = NULL;
  	ItemPointerData decoded;
  	bool		tuplesort_empty = false;
  
  	/*
  	 * sanity checks
  	 */
  	Assert(OidIsValid(indexRelation->rd_rel->relam));
  
  	/*
  	 * Need an EState for evaluation of index expressions and partial-index
  	 * predicates.  Also a slot to hold the current tuple.
  	 */
  	estate = CreateExecutorState();
  	econtext = GetPerTupleExprContext(estate);
  	slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation));
  
  	/* Arrange for econtext's scan tuple to be the tuple under test */
  	econtext->ecxt_scantuple = slot;
  
  	/* Set up execution state for predicate, if any. */
  	predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate);
  
  	/*
  	 * Prepare for scan of the base relation.  We need just those tuples
  	 * satisfying the passed-in reference snapshot.  We must disable syncscan
  	 * here, because it's critical that we read from block zero forward to
  	 * match the sorted TIDs.
  	 */
  	scan = heap_beginscan_strat(heapRelation,	/* relation */
  								snapshot,	/* snapshot */
  								0,	/* number of keys */
  								NULL,	/* scan key */
  								true,	/* buffer access strategy OK */
  								false); /* syncscan not OK */
  
  	/*
  	 * Scan all tuples matching the snapshot.
  	 */
  	while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
  	{
  		/*
  		 * For YugaByte tables, there is no need to find the root tuple. Just
  		 * insert the fetched tuple.
  		 */
  		if (IsYBRelation(heapRelation))
  		{
  			MemoryContextReset(econtext->ecxt_per_tuple_memory);
  
  			/* Set up for predicate or expression evaluation */
  			ExecStoreHeapTuple(heapTuple, slot, false);
  
  			/*
  			 * In a partial index, discard tuples that don't satisfy the
  			 * predicate.
  			 */
  			if (predicate != NULL)
  			{
  				if (!ExecQual(predicate, econtext))
  					continue;
  			}
  
  			/*
  			 * For the current heap tuple, extract all the attributes we use
  			 * in this index, and note which are null.  This also performs
  			 * evaluation of any expressions needed.
  			 */
  			FormIndexDatum(indexInfo,
  						   slot,
  						   estate,
  						   values,
  						   isnull);
  
  			index_insert(indexRelation,
  						 values,
  						 isnull,
  						 NULL,
  						 heapTuple,
  						 heapRelation,
  						 indexInfo->ii_Unique ?
  						 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
  						 indexInfo);
  
  			state->tups_inserted += 1;
  			continue;
  		}
  
  		ItemPointer heapcursor = &heapTuple->t_self;
  		ItemPointerData rootTuple;
  		OffsetNumber root_offnum;
  
  		CHECK_FOR_INTERRUPTS();
  
  		state->htups += 1;
  
  		/*
  		 * As commented in IndexBuildHeapScan, we should index heap-only
  		 * tuples under the TIDs of their root tuples; so when we advance onto
  		 * a new heap page, build a map of root item offsets on the page.
  		 *
  		 * This complicates merging against the tuplesort output: we will
  		 * visit the live tuples in order by their offsets, but the root
  		 * offsets that we need to compare against the index contents might be
  		 * ordered differently.  So we might have to "look back" within the
  		 * tuplesort output, but only within the current page.  We handle that
  		 * by keeping a bool array in_index[] showing all the
  		 * already-passed-over tuplesort output TIDs of the current page. We
  		 * clear that array here, when advancing onto a new heap page.
  		 */
  		if (scan->rs_cblock != root_blkno)
  		{
  			Page		page = BufferGetPage(scan->rs_cbuf);
  
  			LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
  			heap_get_root_tuples(page, root_offsets);
  			LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
  
  			memset(in_index, 0, sizeof(in_index));
  
  			root_blkno = scan->rs_cblock;
  		}
  
  		/* Convert actual tuple TID to root TID */
  		rootTuple = *heapcursor;
  		root_offnum = ItemPointerGetOffsetNumber(heapcursor);
  
  		if (HeapTupleIsHeapOnly(heapTuple))
  		{
  			root_offnum = root_offsets[root_offnum - 1];
  			if (!OffsetNumberIsValid(root_offnum))
  				ereport(ERROR,
  						(errcode(ERRCODE_DATA_CORRUPTED),
  						 errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
  										 ItemPointerGetBlockNumber(heapcursor),
  										 ItemPointerGetOffsetNumber(heapcursor),
  										 RelationGetRelationName(heapRelation))));
  			ItemPointerSetOffsetNumber(&rootTuple, root_offnum);
  		}
  
  		/*
  		 * "merge" by skipping through the index tuples until we find or pass
  		 * the current root tuple.
  		 */
  		while (!tuplesort_empty &&
  			   (!indexcursor ||
  				ItemPointerCompare(indexcursor, &rootTuple) < 0))
  		{
  			Datum		ts_val;
  			bool		ts_isnull;
  
  			if (indexcursor)
  			{
  				/*
  				 * Remember index items seen earlier on the current heap page
  				 */
  				if (ItemPointerGetBlockNumber(indexcursor) == root_blkno)
  					in_index[ItemPointerGetOffsetNumber(indexcursor) - 1] = true;
  			}
  
  			tuplesort_empty = !tuplesort_getdatum(state->tuplesort, true,
  												  &ts_val, &ts_isnull, NULL);
  			Assert(tuplesort_empty || !ts_isnull);
  			if (!tuplesort_empty)
  			{
  				itemptr_decode(&decoded, DatumGetInt64(ts_val));
  				indexcursor = &decoded;
  
  				/* If int8 is pass-by-ref, free (encoded) TID Datum memory */
  #ifndef USE_FLOAT8_BYVAL
  				pfree(DatumGetPointer(ts_val));
  #endif
  			}
  			else
  			{
  				/* Be tidy */
  				indexcursor = NULL;
  			}
  		}
  
  		/*
  		 * If the tuplesort has overshot *and* we didn't see a match earlier,
  		 * then this tuple is missing from the index, so insert it.
  		 */
  		if ((tuplesort_empty ||
  			 ItemPointerCompare(indexcursor, &rootTuple) > 0) &&
  			!in_index[root_offnum - 1])
  		{
  			MemoryContextReset(econtext->ecxt_per_tuple_memory);
  
  			/* Set up for predicate or expression evaluation */
  			ExecStoreHeapTuple(heapTuple, slot, false);
  
  			/*
  			 * In a partial index, discard tuples that don't satisfy the
  			 * predicate.
  			 */
  			if (predicate != NULL)
  			{
  				if (!ExecQual(predicate, econtext))
  					continue;
  			}
  
  			/*
  			 * For the current heap tuple, extract all the attributes we use
  			 * in this index, and note which are null.  This also performs
  			 * evaluation of any expressions needed.
  			 */
  			FormIndexDatum(indexInfo,
  						   slot,
  						   estate,
  						   values,
  						   isnull);
  
  			/*
  			 * You'd think we should go ahead and build the index tuple here,
  			 * but some index AMs want to do further processing on the data
  			 * first. So pass the values[] and isnull[] arrays, instead.
  			 */
  
  			/*
  			 * If the tuple is already committed dead, you might think we
  			 * could suppress uniqueness checking, but this is no longer true
  			 * in the presence of HOT, because the insert is actually a proxy
  			 * for a uniqueness check on the whole HOT-chain.  That is, the
  			 * tuple we have here could be dead because it was already
  			 * HOT-updated, and if so the updating transaction will not have
  			 * thought it should insert index entries.  The index AM will
  			 * check the whole HOT-chain and correctly detect a conflict if
  			 * there is one.
  			 */
  
  			index_insert(indexRelation,
  						 values,
  						 isnull,
  						 &rootTuple,
  						 NULL /* heap tuple */,
  						 heapRelation,
  						 indexInfo->ii_Unique ?
  						 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
  						 indexInfo);
  
  			state->tups_inserted += 1;
  		}
  	}
  
  	heap_endscan(scan);
  
  	ExecDropSingleTupleTableSlot(slot);
  
  	FreeExecutorState(estate);
  
  	/* These may have been pointing to the now-gone estate */
  	indexInfo->ii_ExpressionsState = NIL;
  	indexInfo->ii_PredicateState = NULL;
  }
  
  
  /*
   * index_set_state_flags - adjust pg_index state flags
   *
   * This is used during CREATE/DROP INDEX CONCURRENTLY to adjust the pg_index
   * flags that denote the index's state.  Because the update is not
   * transactional and will not roll back on error, this must only be used as
   * the last step in a transaction that has not made any transactional catalog
   * updates!
   *
   * Note that heap_inplace_update does send a cache inval message for the
   * tuple, so other sessions will hear about the update as soon as we commit.
   *
   * NB: In releases prior to PostgreSQL 9.4, the use of a non-transactional
   * update here would have been unsafe; now that MVCC rules apply even for
   * system catalog scans, we could potentially use a transactional update here
   * instead.
   */
  void
  index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
  {
  	Relation	pg_index;
  	HeapTuple	indexTuple;
  	Form_pg_index indexForm;
  
  	/* Assert that current xact hasn't done any transactional updates */
  	Assert(GetTopTransactionIdIfAny() == InvalidTransactionId);
  
  	/* Open pg_index and fetch a writable copy of the index's tuple */
  	pg_index = heap_open(IndexRelationId, RowExclusiveLock);
  
  	indexTuple = SearchSysCacheCopy1(INDEXRELID,
  									 ObjectIdGetDatum(indexId));
  	if (!HeapTupleIsValid(indexTuple))
  		elog(ERROR, "cache lookup failed for index %u", indexId);
  	indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
  
  	/* Perform the requested state change on the copy */
  	switch (action)
  	{
  		case INDEX_CREATE_SET_READY:
  			/* Set indisready during a CREATE INDEX CONCURRENTLY sequence */
  			Assert(indexForm->indislive);
  			Assert(!indexForm->indisready);
  			Assert(!indexForm->indisvalid);
  			indexForm->indisready = true;
  			break;
  		case INDEX_CREATE_SET_VALID:
  			/* Set indisvalid during a CREATE INDEX CONCURRENTLY sequence */
  			Assert(indexForm->indislive);
  			Assert(indexForm->indisready);
  			Assert(!indexForm->indisvalid);
  			indexForm->indisvalid = true;
  			break;
  		case INDEX_DROP_CLEAR_VALID:
  
  			/*
  			 * Clear indisvalid during a DROP INDEX CONCURRENTLY sequence
  			 *
  			 * If indisready == true we leave it set so the index still gets
  			 * maintained by active transactions.  We only need to ensure that
  			 * indisvalid is false.  (We don't assert that either is initially
  			 * true, though, since we want to be able to retry a DROP INDEX
  			 * CONCURRENTLY that failed partway through.)
  			 *
  			 * Note: the CLUSTER logic assumes that indisclustered cannot be
  			 * set on any invalid index, so clear that flag too.
  			 */
  			indexForm->indisvalid = false;
  			indexForm->indisclustered = false;
  			break;
  		case INDEX_DROP_SET_DEAD:
  
  			/*
  			 * Clear indisready/indislive during DROP INDEX CONCURRENTLY
  			 *
  			 * We clear both indisready and indislive, because we not only
  			 * want to stop updates, we want to prevent sessions from touching
  			 * the index at all.
  			 */
  			Assert(!indexForm->indisvalid);
  			indexForm->indisready = false;
  			indexForm->indislive = false;
  			break;
  	}
  
  	/* ... and write it back in-place */
  	heap_inplace_update(pg_index, indexTuple);
  
  	heap_close(pg_index, RowExclusiveLock);
  }
  
  
  /*
   * IndexGetRelation: given an index's relation OID, get the OID of the
   * relation it is an index on.  Uses the system cache.
   */
  Oid
  IndexGetRelation(Oid indexId, bool missing_ok)
  {
  	HeapTuple	tuple;
  	Form_pg_index index;
  	Oid			result;
  
  	tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexId));
  	if (!HeapTupleIsValid(tuple))
  	{
  		if (missing_ok)
  			return InvalidOid;
  		elog(ERROR, "cache lookup failed for index %u", indexId);
  	}
  	index = (Form_pg_index) GETSTRUCT(tuple);
  	Assert(index->indexrelid == indexId);
  
  	result = index->indrelid;
  	ReleaseSysCache(tuple);
  	return result;
  }
  
  /*
   * reindex_index - This routine is used to recreate a single index
   */
  void
  reindex_index(Oid indexId, bool skip_constraint_checks, char persistence,
  			  int options)
  {
  	Relation	iRel,
  				heapRelation;
  	Oid			heapId;
  	IndexInfo  *indexInfo;
  	volatile bool skipped_constraint = false;
  	PGRUsage	ru0;
  
  	pg_rusage_init(&ru0);
  
  	/*
  	 * Open and lock the parent heap relation.  ShareLock is sufficient since
  	 * we only need to be sure no schema or data changes are going on.
  	 */
  	heapId = IndexGetRelation(indexId, false);
  	heapRelation = heap_open(heapId, ShareLock);
  
  	/*
  	 * Open the target index relation and get an exclusive lock on it, to
  	 * ensure that no one else is touching this particular index.
  	 */
  	iRel = index_open(indexId, AccessExclusiveLock);
  
  	/*
  	 * The case of reindexing partitioned tables and indexes is handled
  	 * differently by upper layers, so this case shouldn't arise.
  	 */
  	if (iRel->rd_rel->relkind == RELKIND_PARTITIONED_INDEX)
  		elog(ERROR, "unsupported relation kind for index \"%s\"",
  			 RelationGetRelationName(iRel));
  
  	/*
  	 * Don't allow reindex on temp tables of other backends ... their local
  	 * buffer manager is not going to cope.
  	 */
  	if (RELATION_IS_OTHER_TEMP(iRel))
  		ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("cannot reindex temporary tables of other sessions")));
  
  	/*
  	 * Also check for active uses of the index in the current transaction; we
  	 * don't want to reindex underneath an open indexscan.
  	 */
  	CheckTableNotInUse(iRel, "REINDEX INDEX");
  
  	/*
  	 * All predicate locks on the index are about to be made invalid. Promote
  	 * them to relation locks on the heap.
  	 */
  	TransferPredicateLocksToHeapRelation(iRel);
  
  	PG_TRY();
  	{
  		/* Suppress use of the target index while rebuilding it */
  		SetReindexProcessing(heapId, indexId);
  
  		/* Fetch info needed for index_build */
  		indexInfo = BuildIndexInfo(iRel);
  
  		/* If requested, skip checking uniqueness/exclusion constraints */
  		if (skip_constraint_checks)
  		{
  			if (indexInfo->ii_Unique || indexInfo->ii_ExclusionOps != NULL)
  				skipped_constraint = true;
  			indexInfo->ii_Unique = false;
  			indexInfo->ii_ExclusionOps = NULL;
  			indexInfo->ii_ExclusionProcs = NULL;
  			indexInfo->ii_ExclusionStrats = NULL;
  		}
  
  		/* We'll build a new physical relation for the index */
  		RelationSetNewRelfilenode(iRel, persistence, InvalidTransactionId,
  								  InvalidMultiXactId);
  
  		/* Initialize the index and rebuild */
  		/* Note: we do not need to re-establish pkey setting */
  		index_build(heapRelation, iRel, indexInfo, false, true, true);
  	}
  	PG_CATCH();
  	{
  		/* Make sure flag gets cleared on error exit */
  		ResetReindexProcessing();
  		PG_RE_THROW();
  	}
  	PG_END_TRY();
  	ResetReindexProcessing();
  
  	/*
  	 * If the index is marked invalid/not-ready/dead (ie, it's from a failed
  	 * CREATE INDEX CONCURRENTLY, or a DROP INDEX CONCURRENTLY failed midway),
  	 * and we didn't skip a uniqueness check, we can now mark it valid.  This
  	 * allows REINDEX to be used to clean up in such cases.
  	 *
  	 * We can also reset indcheckxmin, because we have now done a
  	 * non-concurrent index build, *except* in the case where index_build
  	 * found some still-broken HOT chains. If it did, and we don't have to
  	 * change any of the other flags, we just leave indcheckxmin alone (note
  	 * that index_build won't have changed it, because this is a reindex).
  	 * This is okay and desirable because not updating the tuple leaves the
  	 * index's usability horizon (recorded as the tuple's xmin value) the same
  	 * as it was.
  	 *
  	 * But, if the index was invalid/not-ready/dead and there were broken HOT
  	 * chains, we had better force indcheckxmin true, because the normal
  	 * argument that the HOT chains couldn't conflict with the index is
  	 * suspect for an invalid index.  (A conflict is definitely possible if
  	 * the index was dead.  It probably shouldn't happen otherwise, but let's
  	 * be conservative.)  In this case advancing the usability horizon is
  	 * appropriate.
  	 *
  	 * Another reason for avoiding unnecessary updates here is that while
  	 * reindexing pg_index itself, we must not try to update tuples in it.
  	 * pg_index's indexes should always have these flags in their clean state,
  	 * so that won't happen.
  	 *
  	 * If early pruning/vacuuming is enabled for the heap relation, the
  	 * usability horizon must be advanced to the current transaction on every
  	 * build or rebuild.  pg_index is OK in this regard because catalog tables
  	 * are not subject to early cleanup.
  	 */
  	if (!skipped_constraint)
  	{
  		Relation	pg_index;
  		HeapTuple	indexTuple;
  		Form_pg_index indexForm;
  		bool		index_bad;
  		bool		early_pruning_enabled = EarlyPruningEnabled(heapRelation);
  
  		pg_index = heap_open(IndexRelationId, RowExclusiveLock);
  
  		indexTuple = SearchSysCacheCopy1(INDEXRELID,
  										 ObjectIdGetDatum(indexId));
  		if (!HeapTupleIsValid(indexTuple))
  			elog(ERROR, "cache lookup failed for index %u", indexId);
  		indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
  
  		index_bad = (!indexForm->indisvalid ||
  					 !indexForm->indisready ||
  					 !indexForm->indislive);
  		if (index_bad ||
  			(indexForm->indcheckxmin && !indexInfo->ii_BrokenHotChain) ||
  			early_pruning_enabled)
  		{
  			if (!indexInfo->ii_BrokenHotChain && !early_pruning_enabled)
  				indexForm->indcheckxmin = false;
  			else if (index_bad || early_pruning_enabled)
  				indexForm->indcheckxmin = true;
  			indexForm->indisvalid = true;
  			indexForm->indisready = true;
  			indexForm->indislive = true;
  			CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
  
  			/*
  			 * Invalidate the relcache for the table, so that after we commit
  			 * all sessions will refresh the table's index list.  This ensures
  			 * that if anyone misses seeing the pg_index row during this
  			 * update, they'll refresh their list before attempting any update
  			 * on the table.
  			 */
  			CacheInvalidateRelcache(heapRelation);
  		}
  
  		heap_close(pg_index, RowExclusiveLock);
  	}
  
  	/* Log what we did */
  	if (options & REINDEXOPT_VERBOSE)
  		ereport(INFO,
  				(errmsg("index \"%s\" was reindexed",
  						get_rel_name(indexId)),
  				 errdetail_internal("%s",
  									pg_rusage_show(&ru0))));
  
  	/* Close rels, but keep locks */
  	index_close(iRel, NoLock);
  	heap_close(heapRelation, NoLock);
  }
  
  /*
   * reindex_relation - This routine is used to recreate all indexes
   * of a relation (and optionally its toast relation too, if any).
   *
   * "flags" is a bitmask that can include any combination of these bits:
   *
   * REINDEX_REL_PROCESS_TOAST: if true, process the toast table too (if any).
   *
   * REINDEX_REL_SUPPRESS_INDEX_USE: if true, the relation was just completely
   * rebuilt by an operation such as VACUUM FULL or CLUSTER, and therefore its
   * indexes are inconsistent with it.  This makes things tricky if the relation
   * is a system catalog that we might consult during the reindexing.  To deal
   * with that case, we mark all of the indexes as pending rebuild so that they
   * won't be trusted until rebuilt.  The caller is required to call us *without*
   * having made the rebuilt table visible by doing CommandCounterIncrement;
   * we'll do CCI after having collected the index list.  (This way we can still
   * use catalog indexes while collecting the list.)
   *
   * REINDEX_REL_CHECK_CONSTRAINTS: if true, recheck unique and exclusion
   * constraint conditions, else don't.  To avoid deadlocks, VACUUM FULL or
   * CLUSTER on a system catalog must omit this flag.  REINDEX should be used to
   * rebuild an index if constraint inconsistency is suspected.  For optimal
   * performance, other callers should include the flag only after transforming
   * the data in a manner that risks a change in constraint validity.
   *
   * REINDEX_REL_FORCE_INDEXES_UNLOGGED: if true, set the persistence of the
   * rebuilt indexes to unlogged.
   *
   * REINDEX_REL_FORCE_INDEXES_PERMANENT: if true, set the persistence of the
   * rebuilt indexes to permanent.
   *
   * Returns true if any indexes were rebuilt (including toast table's index
   * when relevant).  Note that a CommandCounterIncrement will occur after each
   * index rebuild.
   */
  bool
  reindex_relation(Oid relid, int flags, int options)
  {
  	Relation	rel;
  	Oid			toast_relid;
  	List	   *indexIds;
  	bool		is_pg_class;
  	bool		result;
  
  	/*
  	 * Open and lock the relation.  ShareLock is sufficient since we only need
  	 * to prevent schema and data changes in it.  The lock level used here
  	 * should match ReindexTable().
  	 */
  	rel = heap_open(relid, ShareLock);
  
  	/*
  	 * This may be useful when implemented someday; but that day is not today.
  	 * For now, avoid erroring out when called in a multi-table context
  	 * (REINDEX SCHEMA) and happen to come across a partitioned table.  The
  	 * partitions may be reindexed on their own anyway.
  	 */
  	if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
  	{
  		ereport(WARNING,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("REINDEX of partitioned tables is not yet implemented, skipping \"%s\"",
  						RelationGetRelationName(rel))));
  		heap_close(rel, ShareLock);
  		return false;
  	}
  
  	toast_relid = rel->rd_rel->reltoastrelid;
  
  	/*
  	 * Get the list of index OIDs for this relation.  (We trust to the
  	 * relcache to get this with a sequential scan if ignoring system
  	 * indexes.)
  	 */
  	indexIds = RelationGetIndexList(rel);
  
  	/*
  	 * reindex_index will attempt to update the pg_class rows for the relation
  	 * and index.  If we are processing pg_class itself, we want to make sure
  	 * that the updates do not try to insert index entries into indexes we
  	 * have not processed yet.  (When we are trying to recover from corrupted
  	 * indexes, that could easily cause a crash.) We can accomplish this
  	 * because CatalogTupleInsert/CatalogTupleUpdate will use the relcache's
  	 * index list to know which indexes to update. We just force the index
  	 * list to be only the stuff we've processed.
  	 *
  	 * It is okay to not insert entries into the indexes we have not processed
  	 * yet because all of this is transaction-safe.  If we fail partway
  	 * through, the updated rows are dead and it doesn't matter whether they
  	 * have index entries.  Also, a new pg_class index will be created with a
  	 * correct entry for its own pg_class row because we do
  	 * RelationSetNewRelfilenode() before we do index_build().
  	 *
  	 * Note that we also clear pg_class's rd_oidindex until the loop is done,
  	 * so that that index can't be accessed either.  This means we cannot
  	 * safely generate new relation OIDs while in the loop; shouldn't be a
  	 * problem.
  	 */
  	is_pg_class = (RelationGetRelid(rel) == RelationRelationId);
  
  	/* Ensure rd_indexattr is valid; see comments for RelationSetIndexList */
  	if (is_pg_class)
  		(void) RelationGetIndexAttrBitmap(rel, INDEX_ATTR_BITMAP_HOT);
  
  	PG_TRY();
  	{
  		List	   *doneIndexes;
  		ListCell   *indexId;
  		char		persistence;
  
  		if (flags & REINDEX_REL_SUPPRESS_INDEX_USE)
  		{
  			/* Suppress use of all the indexes until they are rebuilt */
  			SetReindexPending(indexIds);
  
  			/*
  			 * Make the new heap contents visible --- now things might be
  			 * inconsistent!
  			 */
  			CommandCounterIncrement();
  		}
  
  		/*
  		 * Compute persistence of indexes: same as that of owning rel, unless
  		 * caller specified otherwise.
  		 */
  		if (flags & REINDEX_REL_FORCE_INDEXES_UNLOGGED)
  			persistence = RELPERSISTENCE_UNLOGGED;
  		else if (flags & REINDEX_REL_FORCE_INDEXES_PERMANENT)
  			persistence = RELPERSISTENCE_PERMANENT;
  		else
  			persistence = rel->rd_rel->relpersistence;
  
  		/* Reindex all the indexes. */
  		doneIndexes = NIL;
  		foreach(indexId, indexIds)
  		{
  			Oid			indexOid = lfirst_oid(indexId);
  
  			if (is_pg_class)
  				RelationSetIndexList(rel, doneIndexes, InvalidOid);
  
  			reindex_index(indexOid, !(flags & REINDEX_REL_CHECK_CONSTRAINTS),
  						  persistence, options);
  
  			CommandCounterIncrement();
  
  			/* Index should no longer be in the pending list */
  			Assert(!ReindexIsProcessingIndex(indexOid));
  
  			if (is_pg_class)
  				doneIndexes = lappend_oid(doneIndexes, indexOid);
  		}
  	}
  	PG_CATCH();
  	{
  		/* Make sure list gets cleared on error exit */
  		ResetReindexPending();
  		PG_RE_THROW();
  	}
  	PG_END_TRY();
  	ResetReindexPending();
  
  	if (is_pg_class)
  		RelationSetIndexList(rel, indexIds, ClassOidIndexId);
  
  	/*
  	 * Close rel, but continue to hold the lock.
  	 */
  	heap_close(rel, NoLock);
  
  	result = (indexIds != NIL);
  
  	/*
  	 * If the relation has a secondary toast rel, reindex that too while we
  	 * still hold the lock on the master table.
  	 */
  	if ((flags & REINDEX_REL_PROCESS_TOAST) && OidIsValid(toast_relid))
  		result |= reindex_relation(toast_relid, flags, options);
  
  	return result;
  }
  
  
  /* ----------------------------------------------------------------
   *		System index reindexing support
   *
   * When we are busy reindexing a system index, this code provides support
   * for preventing catalog lookups from using that index.  We also make use
   * of this to catch attempted uses of user indexes during reindexing of
   * those indexes.  This information is propagated to parallel workers;
   * attempting to change it during a parallel operation is not permitted.
   * ----------------------------------------------------------------
   */
  
  static Oid	currentlyReindexedHeap = InvalidOid;
  static Oid	currentlyReindexedIndex = InvalidOid;
  static List *pendingReindexedIndexes = NIL;
  
  /*
   * ReindexIsProcessingHeap
   *		True if heap specified by OID is currently being reindexed.
   */
  bool
  ReindexIsProcessingHeap(Oid heapOid)
  {
  	return heapOid == currentlyReindexedHeap;
  }
  
  /*
   * ReindexIsCurrentlyProcessingIndex
   *		True if index specified by OID is currently being reindexed.
   */
  static bool
  ReindexIsCurrentlyProcessingIndex(Oid indexOid)
  {
  	return indexOid == currentlyReindexedIndex;
  }
  
  /*
   * ReindexIsProcessingIndex
   *		True if index specified by OID is currently being reindexed,
   *		or should be treated as invalid because it is awaiting reindex.
   */
  bool
  ReindexIsProcessingIndex(Oid indexOid)
  {
  	return indexOid == currentlyReindexedIndex ||
  		list_member_oid(pendingReindexedIndexes, indexOid);
  }
  
  /*
   * SetReindexProcessing
   *		Set flag that specified heap/index are being reindexed.
   *
   * NB: caller must use a PG_TRY block to ensure ResetReindexProcessing is done.
   */
  static void
  SetReindexProcessing(Oid heapOid, Oid indexOid)
  {
  	Assert(OidIsValid(heapOid) && OidIsValid(indexOid));
  	/* Reindexing is not re-entrant. */
  	if (OidIsValid(currentlyReindexedHeap))
  		elog(ERROR, "cannot reindex while reindexing");
  	currentlyReindexedHeap = heapOid;
  	currentlyReindexedIndex = indexOid;
  	/* Index is no longer "pending" reindex. */
  	RemoveReindexPending(indexOid);
  }
  
  /*
   * ResetReindexProcessing
   *		Unset reindexing status.
   */
  static void
  ResetReindexProcessing(void)
  {
  	/* This may be called in leader error path */
  	currentlyReindexedHeap = InvalidOid;
  	currentlyReindexedIndex = InvalidOid;
  }
  
  /*
   * SetReindexPending
   *		Mark the given indexes as pending reindex.
   *
   * NB: caller must use a PG_TRY block to ensure ResetReindexPending is done.
   * Also, we assume that the current memory context stays valid throughout.
   */
  static void
  SetReindexPending(List *indexes)
  {
  	/* Reindexing is not re-entrant. */
  	if (pendingReindexedIndexes)
  		elog(ERROR, "cannot reindex while reindexing");
  	if (IsInParallelMode())
  		elog(ERROR, "cannot modify reindex state during a parallel operation");
  	pendingReindexedIndexes = list_copy(indexes);
  }
  
  /*
   * RemoveReindexPending
   *		Remove the given index from the pending list.
   */
  static void
  RemoveReindexPending(Oid indexOid)
  {
  	if (IsInParallelMode())
  		elog(ERROR, "cannot modify reindex state during a parallel operation");
  	pendingReindexedIndexes = list_delete_oid(pendingReindexedIndexes,
  											  indexOid);
  }
  
  /*
   * ResetReindexPending
   *		Unset reindex-pending status.
   */
  static void
  ResetReindexPending(void)
  {
  	/* This may be called in leader error path */
  	pendingReindexedIndexes = NIL;
  }
  
  /*
   * EstimateReindexStateSpace
   *		Estimate space needed to pass reindex state to parallel workers.
   */
  Size
  EstimateReindexStateSpace(void)
  {
  	return offsetof(SerializedReindexState, pendingReindexedIndexes)
  		+ mul_size(sizeof(Oid), list_length(pendingReindexedIndexes));
  }
  
  /*
   * SerializeReindexState
   *		Serialize reindex state for parallel workers.
   */
  void
  SerializeReindexState(Size maxsize, char *start_address)
  {
  	SerializedReindexState *sistate = (SerializedReindexState *) start_address;
  	int			c = 0;
  	ListCell   *lc;
  
  	sistate->currentlyReindexedHeap = currentlyReindexedHeap;
  	sistate->currentlyReindexedIndex = currentlyReindexedIndex;
  	sistate->numPendingReindexedIndexes = list_length(pendingReindexedIndexes);
  	foreach(lc, pendingReindexedIndexes)
  		sistate->pendingReindexedIndexes[c++] = lfirst_oid(lc);
  }
  
  /*
   * RestoreReindexState
   *		Restore reindex state in a parallel worker.
   */
  void
  RestoreReindexState(void *reindexstate)
  {
  	SerializedReindexState *sistate = (SerializedReindexState *) reindexstate;
  	int			c = 0;
  	MemoryContext oldcontext;
  
  	currentlyReindexedHeap = sistate->currentlyReindexedHeap;
  	currentlyReindexedIndex = sistate->currentlyReindexedIndex;
  
  	Assert(pendingReindexedIndexes == NIL);
  	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
  	for (c = 0; c < sistate->numPendingReindexedIndexes; ++c)
  		pendingReindexedIndexes =
  			lappend_oid(pendingReindexedIndexes,
  						sistate->pendingReindexedIndexes[c]);
  	MemoryContextSwitchTo(oldcontext);
  }
  