text: /*-------------------------------------------------------------------------
   *
   * heap.c
   *	  code to create and destroy POSTGRES heap relations
   *
   * Portions Copyright (c) 2005-2010, Greenplum inc
   * Portions Copyright (c) 2012-Present Pivotal Software, Inc.
   * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.373 2010/04/05 01:09:52 tgl Exp $
   *
   *
   * INTERFACE ROUTINES
   *		heap_create()			- Create an uncataloged heap relation
   *		heap_create_with_catalog() - Create a cataloged relation
   *		heap_drop_with_catalog() - Removes named relation from catalogs
   *
   * NOTES
   *	  this code taken from access/heap/create.c, which contains
   *	  the old heap_create_with_catalog, amcreate, and amdestroy.
   *	  those routines will soon call these routines using the function
   *	  manager,
   *	  just like the poorly named "NewXXX" routines do.	The
   *	  "New" routines are all going to die soon, once and for all!
   *		-cim 1/13/91
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/genam.h"
  #include "access/heapam.h"
  #include "access/sysattr.h"
  #include "access/transam.h"
  #include "access/reloptions.h"
  #include "access/xact.h"
  #include "catalog/catalog.h"
  #include "catalog/dependency.h"
  #include "catalog/gp_policy.h"
  #include "catalog/heap.h"
  #include "catalog/index.h"
  #include "catalog/indexing.h"
  #include "catalog/namespace.h"
  #include "catalog/pg_appendonly_fn.h"
  #include "catalog/pg_attrdef.h"
  #include "catalog/pg_attribute_encoding.h"
  #include "catalog/pg_authid.h"
  #include "catalog/pg_auth_members.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_database.h"
  #include "catalog/pg_exttable.h"
  #include "catalog/pg_inherits.h"
  #include "catalog/pg_namespace.h"
  #include "catalog/pg_partition.h"
  #include "catalog/pg_partition_rule.h"
  #include "catalog/pg_statistic.h"
  #include "catalog/pg_stat_last_operation.h"
  #include "catalog/pg_stat_last_shoperation.h"
  #include "catalog/pg_tablespace.h"
  #include "catalog/pg_type.h"
  #include "catalog/pg_type_fn.h"
  #include "catalog/storage.h"
  #include "commands/tablecmds.h"
  #include "commands/typecmds.h"
  #include "miscadmin.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/var.h"
  #include "parser/parse_coerce.h"
  #include "parser/parse_expr.h"
  #include "parser/parse_relation.h"
  #include "storage/bufmgr.h"
  #include "storage/freespace.h"
  #include "storage/smgr.h"
  #include "utils/acl.h"
  #include "utils/builtins.h"
  #include "utils/fmgroids.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"             /* CDB: GetMemoryChunkContext */
  #include "utils/relcache.h"
  #include "utils/snapmgr.h"
  #include "utils/syscache.h"
  #include "utils/tqual.h"
  
  #include "cdb/cdbpartition.h"
  #include "cdb/cdbsreh.h"
  #include "cdb/cdbvars.h"
  
  #include "utils/guc.h"
  
  static void MetaTrackAddUpdInternal(Oid			classid,
  									Oid			objoid,
  									Oid			relowner,
  									char*		actionname,
  									char*		subtype,
  									Relation	rel,
  									HeapTuple	old_tuple);
  
  
  
  /* Kluge for upgrade-in-place support */
  Oid			binary_upgrade_next_heap_relfilenode = InvalidOid;
  Oid			binary_upgrade_next_toast_relfilenode = InvalidOid;
  
  static void AddNewRelationTuple(Relation pg_class_desc,
  					Relation new_rel_desc,
  					Oid new_rel_oid,
  					Oid new_type_oid,
  					Oid reloftype,
  					Oid relowner,
  					char relkind,
  					char relstorage,
  					Datum relacl,
  					Datum reloptions);
  static Oid AddNewRelationType(const char *typeName,
  				   Oid typeNamespace,
  				   Oid new_rel_oid,
  				   char new_rel_kind,
  				   Oid ownerid,
  				   Oid new_row_type,
  				   Oid new_array_type);
  static void RelationRemoveInheritance(Oid relid);
  static void StoreRelCheck(Relation rel, char *ccname, Node *expr,
  			  bool is_local, int inhcount);
  static void StoreConstraints(Relation rel, List *cooked_constraints);
  static bool MergeWithExistingConstraint(Relation rel, char *ccname, Node *expr,
  							bool allow_merge, bool is_local);
  static Node *cookConstraint(ParseState *pstate,
  			   Node *raw_constraint,
  			   char *relname);
  static List *insert_ordered_unique_oid(List *list, Oid datum);
  
  /* ----------------------------------------------------------------
   *				XXX UGLY HARD CODED BADNESS FOLLOWS XXX
   *
   *		these should all be moved to someplace in the lib/catalog
   *		module, if not obliterated first.
   * ----------------------------------------------------------------
   */
  
  
  /*
   * Note:
   *		Should the system special case these attributes in the future?
   *		Advantage:	consume much less space in the ATTRIBUTE relation.
   *		Disadvantage:  special cases will be all over the place.
   */
  
  /*
   * The initializers below do not include the attoptions or attacl fields,
   * but that's OK - we're never going to reference anything beyond the
   * fixed-size portion of the structure anyway.
   */
  
  static FormData_pg_attribute a1 = {
  	0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
  	SelfItemPointerAttributeNumber, 0, -1, -1,
  	false, 'p', 's', true, false, false, true, 0
  };
  
  static FormData_pg_attribute a2 = {
  	0, {"oid"}, OIDOID, 0, sizeof(Oid),
  	ObjectIdAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  static FormData_pg_attribute a3 = {
  	0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
  	MinTransactionIdAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  static FormData_pg_attribute a4 = {
  	0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
  	MinCommandIdAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  static FormData_pg_attribute a5 = {
  	0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
  	MaxTransactionIdAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  static FormData_pg_attribute a6 = {
  	0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
  	MaxCommandIdAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  /*
   * We decided to call this attribute "tableoid" rather than say
   * "classoid" on the basis that in the future there may be more than one
   * table of a particular class/type. In any case table is still the word
   * used in SQL.
   */
  static FormData_pg_attribute a7 = {
  	0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
  	TableOidAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  /*CDB*/
  static FormData_pg_attribute a8 = {
  	0, {"gp_segment_id"}, INT4OID, 0, sizeof(gpsegmentId),
  	GpSegmentIdAttributeNumber, 0, -1, -1,
  	true, 'p', 'i', true, false, false, true, 0
  };
  
  static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7, &a8};
  
  /*
   * This function returns a Form_pg_attribute pointer for a system attribute.
   * Note that we elog if the presented attno is invalid, which would only
   * happen if there's a problem upstream.
   */
  Form_pg_attribute
  SystemAttributeDefinition(AttrNumber attno, bool relhasoids)
  {
  	if (attno >= 0 || attno < -(int) lengthof(SysAtt))
  		elog(ERROR, "invalid system attribute number %d", attno);
  	if (attno == ObjectIdAttributeNumber && !relhasoids)
  		elog(ERROR, "invalid system attribute number %d", attno);
  	return SysAtt[-attno - 1];
  }
  
  /*
   * If the given name is a system attribute name, return a Form_pg_attribute
   * pointer for a prototype definition.	If not, return NULL.
   */
  Form_pg_attribute
  SystemAttributeByName(const char *attname, bool relhasoids)
  {
  	int			j;
  
  	for (j = 0; j < (int) lengthof(SysAtt); j++)
  	{
  		Form_pg_attribute att = SysAtt[j];
  
  		if (relhasoids || att->attnum != ObjectIdAttributeNumber)
  		{
  			if (strcmp(NameStr(att->attname), attname) == 0)
  				return att;
  		}
  	}
  
  	return NULL;
  }
  
  
  /* ----------------------------------------------------------------
   *				XXX END OF UGLY HARD CODED BADNESS XXX
   * ---------------------------------------------------------------- */
  
  
  /* ----------------------------------------------------------------
   *		heap_create		- Create an uncataloged heap relation
   *
   *		Note API change: the caller must now always provide the OID
   *		to use for the relation.
   *
   *		rel->rd_rel is initialized by RelationBuildLocalRelation,
   *		and is mostly zeroes at return.
   * ----------------------------------------------------------------
   */
  Relation
  heap_create(const char *relname,
  			Oid relnamespace,
  			Oid reltablespace,
  			Oid relid,
  			TupleDesc tupDesc,
  			Oid relam,
  			char relkind,
  			char relstorage,
  			bool shared_relation,
  			bool mapped_relation,
  			bool allow_system_table_mods)
  {
  	bool		create_storage;
  	Relation	rel;
  
  	/* The caller must have provided an OID for the relation. */
  	Assert(OidIsValid(relid));
  
  	/*
  	 * sanity checks
  	 */
  	if (!allow_system_table_mods &&
  		(IsSystemNamespace(relnamespace) || IsToastNamespace(relnamespace) ||
  		 IsAoSegmentNamespace(relnamespace)) && IsNormalProcessingMode())
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("permission denied to create \"%s.%s\"",
  						get_namespace_name(relnamespace), relname),
  		errdetail("System catalog modifications are currently disallowed.")));
  
  	/*
  	 * Decide if we need storage or not, and handle a couple other special
  	 * cases for particular relkinds.
  	 */
  	switch (relkind)
  	{
  		case RELKIND_VIEW:
  		case RELKIND_COMPOSITE_TYPE:
  			create_storage = false;
  
  			/*
  			 * Force reltablespace to zero if the relation has no physical
  			 * storage.  This is mainly just for cleanliness' sake.
  			 */
  			reltablespace = InvalidOid;
  			break;
  		case RELKIND_SEQUENCE:
  			create_storage = true;
  
  			/*
  			 * Force reltablespace to zero for sequences, since we don't
  			 * support moving them around into different tablespaces.
  			 */
  			reltablespace = InvalidOid;
  			break;
  		default:
  			if(relstorage_is_external(relstorage))
  				create_storage = false;
  			else
  				create_storage = true;
  			break;
  	}
  
  	/*
  	 * Never allow a pg_class entry to explicitly specify the database's
  	 * default tablespace in reltablespace; force it to zero instead. This
  	 * ensures that if the database is cloned with a different default
  	 * tablespace, the pg_class entry will still match where CREATE DATABASE
  	 * will put the physically copied relation.
  	 *
  	 * Yes, this is a bit of a hack.
  	 */
  	if (reltablespace == MyDatabaseTableSpace)
  		reltablespace = InvalidOid;
  
  	/*
  	 * build the relcache entry.
  	 */
  	rel = RelationBuildLocalRelation(relname,
  									 relnamespace,
  									 tupDesc,
  									 relid,
  									 reltablespace,
                                       relkind,           /*CDB*/
  									 shared_relation,
  									 mapped_relation);
  
  	/*
  	 * Have the storage manager create the relation's disk file, if needed.
  	 *
  	 * We only create the main fork here, other forks will be created on
  	 * demand.
  	 */
  	if (create_storage)
  	{
  		bool isAppendOnly;
  
  		// WARNING: Do not use the rel structure -- it doesn't have relstorage set...
  		isAppendOnly = (relstorage == RELSTORAGE_AOROWS || relstorage == RELSTORAGE_AOCOLS);
  
  		RelationOpenSmgr(rel);
  		RelationCreateStorage(rel->rd_node, rel->rd_istemp);
  
  		/*
  		 * AO tables don't use the buffer manager, better to not keep the
  		 * smgr open for it.
  		 */
  		if (isAppendOnly)
  			RelationCloseSmgr(rel);
  	}
  
  	return rel;
  }
  
  /* ----------------------------------------------------------------
   *		heap_create_with_catalog		- Create a cataloged relation
   *
   *		this is done in multiple steps:
   *
   *		1) CheckAttributeNamesTypes() is used to make certain the tuple
   *		   descriptor contains a valid set of attribute names and types
   *
   *		2) pg_class is opened and get_relname_relid()
   *		   performs a scan to ensure that no relation with the
   *		   same name already exists.
   *
   *		3) heap_create() is called to create the new relation on disk.
   *
   *		4) TypeCreate() is called to define a new type corresponding
   *		   to the new relation.
   *
   *		5) AddNewRelationTuple() is called to register the
   *		   relation in pg_class.
   *
   *		6) AddNewAttributeTuples() is called to register the
   *		   new relation's schema in pg_attribute.
   *
   *		7) StoreConstraints is called ()		- vadim 08/22/97
   *
   *		8) the relations are closed and the new relation's oid
   *		   is returned.
   *
   * ----------------------------------------------------------------
   */
  
  /* --------------------------------
   *		CheckAttributeNamesTypes
   *
   *		this is used to make certain the tuple descriptor contains a
   *		valid set of attribute names and datatypes.  a problem simply
   *		generates ereport(ERROR) which aborts the current transaction.
   * --------------------------------
   */
  void
  CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind,
  						 bool allow_system_table_mods)
  {
  	int			i;
  	int			j;
  	int			natts = tupdesc->natts;
  
  	/* Sanity check on column count */
  	if (natts < 0 || natts > MaxHeapAttributeNumber)
  		ereport(ERROR,
  				(errcode(ERRCODE_TOO_MANY_COLUMNS),
  				 errmsg("tables can have at most %d columns",
  						MaxHeapAttributeNumber)));
  
  	/*
  	 * first check for collision with system attribute names
  	 *
  	 * Skip this for a view or type relation, since those don't have system
  	 * attributes.
  	 */
  	if (relkind != RELKIND_VIEW && relkind != RELKIND_COMPOSITE_TYPE)
  	{
  		for (i = 0; i < natts; i++)
  		{
  			if (SystemAttributeByName(NameStr(tupdesc->attrs[i]->attname),
  									  tupdesc->tdhasoid) != NULL)
  				ereport(ERROR,
  						(errcode(ERRCODE_DUPLICATE_COLUMN),
  						 errmsg("column name \"%s\" conflicts with a system column name",
  								NameStr(tupdesc->attrs[i]->attname))));
  		}
  	}
  
  	/*
  	 * next check for repeated attribute names
  	 */
  	for (i = 1; i < natts; i++)
  	{
  		for (j = 0; j < i; j++)
  		{
  			if (strcmp(NameStr(tupdesc->attrs[j]->attname),
  					   NameStr(tupdesc->attrs[i]->attname)) == 0)
  				ereport(ERROR,
  						(errcode(ERRCODE_DUPLICATE_COLUMN),
  						 errmsg("column name \"%s\" specified more than once",
  								NameStr(tupdesc->attrs[j]->attname))));
  		}
  	}
  
  	/*
  	 * next check the attribute types
  	 */
  	for (i = 0; i < natts; i++)
  	{
  		CheckAttributeType(NameStr(tupdesc->attrs[i]->attname),
  						   tupdesc->attrs[i]->atttypid,
  						   NIL,	/* assume we're creating a new rowtype */
  						   allow_system_table_mods);
  	}
  }
  
  /* --------------------------------
   *		CheckAttributeType
   *
   *		Verify that the proposed datatype of an attribute is legal.
   *		This is needed mainly because there are types (and pseudo-types)
   *		in the catalogs that we do not support as elements of real tuples.
   *		We also check some other properties required of a table column.
   *
   * If the attribute is being proposed for addition to an existing table or
   * composite type, pass a one-element list of the rowtype OID as
   * containing_rowtypes.  When checking a to-be-created rowtype, it's
   * sufficient to pass NIL, because there could not be any recursive reference
   * to a not-yet-existing rowtype.
   * --------------------------------
   */
  void
  CheckAttributeType(const char *attname, Oid atttypid,
  				   List *containing_rowtypes,
  				   bool allow_system_table_mods)
  {
  	char		att_typtype = get_typtype(atttypid);
  	Oid			att_typelem;
  
  	if (Gp_role == GP_ROLE_EXECUTE)
  	{
  		/*
  		 * In executor nodes, don't bother checking, as the dispatcher should've
  		 * checked this already.
  		 */
  		return;
  	}
  
  	if (atttypid == UNKNOWNOID)
  	{
  		/*
  		 * Warn user, but don't fail, if column to be created has UNKNOWN type
  		 * (usually as a result of a 'retrieve into' - jolly)
  		 */
  		ereport(WARNING,
  				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  				 errmsg("column \"%s\" has type \"unknown\"", attname),
  				 errdetail("Proceeding with relation creation anyway.")));
  	}
  	else if (att_typtype == TYPTYPE_PSEUDO)
  	{
  		/*
  		 * Refuse any attempt to create a pseudo-type column, except for a
  		 * special hack for pg_statistic: allow ANYARRAY when modifying system
  		 * catalogs (this allows creating pg_statistic and cloning it during
  		 * VACUUM FULL)
  		 */
  		if (atttypid != ANYARRAYOID || !allow_system_table_mods)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("column \"%s\" has pseudo-type %s",
  							attname, format_type_be(atttypid))));
  	}
  	else if (att_typtype == TYPTYPE_COMPOSITE)
  	{
  		/*
  		 * For a composite type, recurse into its attributes.  You might think
  		 * this isn't necessary, but since we allow system catalogs to break
  		 * the rule, we have to guard against the case.
  		 */
  		Relation	relation;
  		TupleDesc	tupdesc;
  		int			i;
  
  		/*
  		 * Check for self-containment.  Eventually we might be able to allow
  		 * this (just return without complaint, if so) but it's not clear how
  		 * many other places would require anti-recursion defenses before it
  		 * would be safe to allow tables to contain their own rowtype.
  		 */
  		if (list_member_oid(containing_rowtypes, atttypid))
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					 errmsg("composite type %s cannot be made a member of itself",
  							format_type_be(atttypid))));
  
  		containing_rowtypes = lcons_oid(atttypid, containing_rowtypes);
  
  		relation = relation_open(get_typ_typrelid(atttypid), AccessShareLock);
  
  		tupdesc = RelationGetDescr(relation);
  
  		for (i = 0; i < tupdesc->natts; i++)
  		{
  			Form_pg_attribute attr = tupdesc->attrs[i];
  
  			if (attr->attisdropped)
  				continue;
  			CheckAttributeType(NameStr(attr->attname), attr->atttypid,
  							   containing_rowtypes,
  							   allow_system_table_mods);
  		}
  
  		relation_close(relation, AccessShareLock);
  
  		containing_rowtypes = list_delete_first(containing_rowtypes);
  	}
  	else if (OidIsValid((att_typelem = get_element_type(atttypid))))
  	{
  		/*
  		 * Must recurse into array types, too, in case they are composite.
  		 */
  		CheckAttributeType(attname, att_typelem,
  						   containing_rowtypes,
  						   allow_system_table_mods);
  	}
  }
  
  /* MPP-6929: metadata tracking */
  /* --------------------------------
   *		MetaTrackAddObject
   *
   *		Track creation of object in pg_stat_last_operation. The
   *		arguments are:
   *
   *		classid		- the oid of the table containing the object, eg
   *					  "pg_class" for a relation
   *		objoid		- the oid of the object itself in the specified table
   *		relowner	- role ? user ?
   *		actionname	- generally CREATE for this case
   *		subtype		- some generic descriptive, eg TABLE for a "CREATE TABLE"
   *
   *
   * --------------------------------
   */
  
  static void MetaTrackAddUpdInternal(Oid			classid,
  									Oid			objoid,
  									Oid			relowner,
  									char*		actionname,
  									char*		subtype,
  									Relation	rel,
  									HeapTuple	old_tuple)
  {
  	HeapTuple	new_tuple;
  	Datum		values[Natts_pg_statlastop];
  	bool		isnull[Natts_pg_statlastop];
  	bool		new_record_repl[Natts_pg_statlastop];
  	NameData	uname;
  	NameData	aname;
  	HeapTuple	roletup;
  
  	MemSet(isnull, 0, sizeof(bool) * Natts_pg_statlastop);
  	MemSet(new_record_repl, 0, sizeof(bool) * Natts_pg_statlastop);
  
  	values[Anum_pg_statlastop_classid - 1] = ObjectIdGetDatum(classid);
  	values[Anum_pg_statlastop_objid - 1] = ObjectIdGetDatum(objoid);
  
  	aname.data[0] = '\0';
  	namestrcpy(&aname, actionname);
  	values[Anum_pg_statlastop_staactionname - 1] = NameGetDatum(&aname);
  
  	values[Anum_pg_statlastop_stasysid - 1] = ObjectIdGetDatum(relowner);
  	/* set this column to update */
  	new_record_repl[Anum_pg_statlastop_stasysid - 1] = true;
  
  	uname.data[0] = '\0';
  
  	roletup = SearchSysCache(AUTHOID,
  							 ObjectIdGetDatum(relowner),
  							 0, 0, 0);
  	if (HeapTupleIsValid(roletup))
  	{
  		Form_pg_authid authid_tup = (Form_pg_authid) GETSTRUCT(roletup);
  
  		namecpy(&uname, &authid_tup->rolname);
  		ReleaseSysCache(roletup);
  	}
  	else
  	{
  		/* Generate numeric OID if we don't find an entry */
  		sprintf(NameStr(uname), "%u", relowner);
  	}
  
  	values[Anum_pg_statlastop_stausename - 1] = NameGetDatum(&uname);
  	/* set this column to update */
  	new_record_repl[Anum_pg_statlastop_stausename - 1] = true;
  
  	values[Anum_pg_statlastop_stasubtype - 1] = CStringGetTextDatum(subtype);
  	/* set this column to update */
  	new_record_repl[Anum_pg_statlastop_stasubtype - 1] = true;
  
  	values[Anum_pg_statlastop_statime - 1] = GetCurrentTimestamp();
  	/* set this column to update */
  	new_record_repl[Anum_pg_statlastop_statime - 1] = true;
  
  	if (HeapTupleIsValid(old_tuple))
  	{
  		new_tuple = heap_modify_tuple(old_tuple, RelationGetDescr(rel),
  									  values,
  									  isnull, new_record_repl);
  		simple_heap_update(rel, &old_tuple->t_self, new_tuple);
  		CatalogUpdateIndexes(rel, new_tuple);
  	}
  	else
  	{
  		new_tuple = heap_form_tuple(RelationGetDescr(rel), values, isnull);
  
  		simple_heap_insert(rel, new_tuple);
  		CatalogUpdateIndexes(rel, new_tuple);
  	}
  
  	if (HeapTupleIsValid(old_tuple))
  		heap_freetuple(new_tuple);
  
  } /* end MetaTrackAddUpdInternal */
  
  
  void MetaTrackAddObject(Oid		classid, 
  						Oid		objoid, 
  						Oid		relowner,
  						char*	actionname,
  						char*	subtype)
  {
  	Relation	rel;
  
  	if (IsBootstrapProcessingMode())
  		return;
  
  	if (IsSharedRelation(classid))
  	{
  		rel = heap_open(StatLastShOpRelationId, RowExclusiveLock);
  	}
  	else
  	{
  		rel = heap_open(StatLastOpRelationId, RowExclusiveLock);
  	}
  
  	MetaTrackAddUpdInternal(classid, objoid, relowner,
  							actionname, subtype,
  							rel, NULL);
  
  	heap_close(rel, RowExclusiveLock);
  
  /*	CommandCounterIncrement(); */
  
  } /* end MetaTrackAddObject */
  
  void MetaTrackUpdObject(Oid		classid, 
  						Oid		objoid, 
  						Oid		relowner,
  						char*	actionname,
  						char*	subtype)
  {
  	HeapTuple	tuple;
  	ScanKeyData key[3];
  	SysScanDesc desc;
  	Relation	rel;
  	int			ii = 0;
  
  	if (IsBootstrapProcessingMode())
  		return;
  
  	if (IsSharedRelation(classid))
  	{
  		rel = heap_open(StatLastShOpRelationId, RowExclusiveLock);
  
  		ScanKeyInit(&key[0],
  					Anum_pg_statlastshop_classid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(classid));
  		ScanKeyInit(&key[1],
  					Anum_pg_statlastshop_objid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(objoid));
  		ScanKeyInit(&key[2],
  					Anum_pg_statlastshop_staactionname,
  					BTEqualStrategyNumber, F_NAMEEQ,
  					CStringGetDatum(actionname));
  
  		desc = systable_beginscan(rel,
  								  StatLastShOpClassidObjidStaactionnameIndexId,
  								  true,
  								  SnapshotNow, 3, key);
  	}
  	else
  	{
  		rel = heap_open(StatLastOpRelationId, RowExclusiveLock);
  
  		ScanKeyInit(&key[0],
  					Anum_pg_statlastop_classid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(classid));
  		ScanKeyInit(&key[1],
  					Anum_pg_statlastop_objid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(objoid));
  		ScanKeyInit(&key[2],
  					Anum_pg_statlastop_staactionname,
  					BTEqualStrategyNumber, F_NAMEEQ,
  					CStringGetDatum(actionname));
  
  		desc = systable_beginscan(rel,
  								  StatLastOpClassidObjidStaactionnameIndexId,
  								  true,
  								  SnapshotNow, 3, key);
  	}
  
  	/* should be a unique index - only 1 answer... */
  	while (HeapTupleIsValid(tuple = systable_getnext(desc)))
  	{
  		MetaTrackAddUpdInternal(classid, objoid, relowner,
  								actionname, subtype,
  								rel, tuple);
  		ii++;
  	}
  	systable_endscan(desc);
  	heap_close(rel, RowExclusiveLock);
  
  	/* add it if it didn't already exist */
  	if (!ii)
  		MetaTrackAddObject(classid, 
  						   objoid, 
  						   relowner,
  						   actionname,
  						   subtype);
  
  } /* end MetaTrackUpdObject */
  void MetaTrackDropObject(Oid		classid, 
  						 Oid		objoid)
  {
  	HeapTuple	tuple;
  	ScanKeyData key[3];
  	SysScanDesc desc;
  	Relation	rel;
  
  	if (IsSharedRelation(classid))
  	{
  		/* DELETE FROM pg_stat_last_shoperation WHERE classid = :1 AND objid = :2 */
  
  		rel = heap_open(StatLastShOpRelationId, RowExclusiveLock);
  
  		ScanKeyInit(&key[0],
  					Anum_pg_statlastshop_classid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(classid));
  		ScanKeyInit(&key[1],
  					Anum_pg_statlastshop_objid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(objoid));
  
  		desc = systable_beginscan(rel,
  								  StatLastShOpClassidObjidStaactionnameIndexId,
  								  true,
  								  SnapshotNow, 2, key);
  	}
  	else
  	{
  		/* DELETE FROM pg_stat_last_operation WHERE classid = :1 AND objid = :2 */
  		rel = heap_open(StatLastOpRelationId, RowExclusiveLock);
  
  		ScanKeyInit(&key[0],
  					Anum_pg_statlastop_classid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(classid));
  		ScanKeyInit(&key[1],
  					Anum_pg_statlastop_objid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(objoid));
  
  		desc = systable_beginscan(rel,
  								  StatLastOpClassidObjidStaactionnameIndexId,
  								  true,
  								  SnapshotNow, 2, key);
  	}
  
  	while (HeapTupleIsValid(tuple = systable_getnext(desc)))
  		simple_heap_delete(rel, &tuple->t_self);
  
  	systable_endscan(desc);
  	heap_close(rel, RowExclusiveLock);
  
  } /* end MetaTrackDropObject */
  
  /*
   * InsertPgAttributeTuple
   *		Construct and insert a new tuple in pg_attribute.
   *
   * Caller has already opened and locked pg_attribute.  new_attribute is the
   * attribute to insert (but we ignore attacl and attoptions, which are always
   * initialized to NULL).
   *
   * indstate is the index state for CatalogIndexInsert.	It can be passed as
   * NULL, in which case we'll fetch the necessary info.  (Don't do this when
   * inserting multiple attributes, because it's a tad more expensive.)
   */
  void
  InsertPgAttributeTuple(Relation pg_attribute_rel,
  					   Form_pg_attribute new_attribute,
  					   CatalogIndexState indstate)
  {
  	Datum		values[Natts_pg_attribute];
  	bool		nulls[Natts_pg_attribute];
  	HeapTuple	tup;
  
  	/* This is a tad tedious, but way cleaner than what we used to do... */
  	memset(values, 0, sizeof(values));
  	memset(nulls, false, sizeof(nulls));
  
  	values[Anum_pg_attribute_attrelid - 1] = ObjectIdGetDatum(new_attribute->attrelid);
  	values[Anum_pg_attribute_attname - 1] = NameGetDatum(&new_attribute->attname);
  	values[Anum_pg_attribute_atttypid - 1] = ObjectIdGetDatum(new_attribute->atttypid);
  	values[Anum_pg_attribute_attstattarget - 1] = Int32GetDatum(new_attribute->attstattarget);
  	values[Anum_pg_attribute_attlen - 1] = Int16GetDatum(new_attribute->attlen);
  	values[Anum_pg_attribute_attnum - 1] = Int16GetDatum(new_attribute->attnum);
  	values[Anum_pg_attribute_attndims - 1] = Int32GetDatum(new_attribute->attndims);
  	values[Anum_pg_attribute_attcacheoff - 1] = Int32GetDatum(new_attribute->attcacheoff);
  	values[Anum_pg_attribute_atttypmod - 1] = Int32GetDatum(new_attribute->atttypmod);
  	values[Anum_pg_attribute_attbyval - 1] = BoolGetDatum(new_attribute->attbyval);
  	values[Anum_pg_attribute_attstorage - 1] = CharGetDatum(new_attribute->attstorage);
  	values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
  	values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
  	values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
  	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
  	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
  	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
  
  	/* start out with empty permissions and empty options */
  	nulls[Anum_pg_attribute_attacl - 1] = true;
  	nulls[Anum_pg_attribute_attoptions - 1] = true;
  
  	tup = heap_form_tuple(RelationGetDescr(pg_attribute_rel), values, nulls);
  
  	/* finally insert the new tuple, update the indexes, and clean up */
  	simple_heap_insert(pg_attribute_rel, tup);
  
  	if (indstate != NULL)
  		CatalogIndexInsert(indstate, tup);
  	else
  		CatalogUpdateIndexes(pg_attribute_rel, tup);
  
  	heap_freetuple(tup);
  }
  
  /* --------------------------------
   *		AddNewAttributeTuples
   *
   *		this registers the new relation's schema by adding
   *		tuples to pg_attribute.
   * --------------------------------
   */
  static void
  AddNewAttributeTuples(Oid new_rel_oid,
  					  TupleDesc tupdesc,
  					  char relkind,
  					  bool oidislocal,
  					  int oidinhcount)
  {
  	Form_pg_attribute attr;
  	int			i;
  	Relation	rel;
  	CatalogIndexState indstate;
  	int			natts = tupdesc->natts;
  	ObjectAddress myself,
  				referenced;
  
  	/*
  	 * open pg_attribute and its indexes.
  	 */
  	rel = heap_open(AttributeRelationId, RowExclusiveLock);
  
  	indstate = CatalogOpenIndexes(rel);
  
  	/*
  	 * First we add the user attributes.  This is also a convenient place to
  	 * add dependencies on their datatypes.
  	 */
  	for (i = 0; i < natts; i++)
  	{
  		attr = tupdesc->attrs[i];
  		/* Fill in the correct relation OID */
  		attr->attrelid = new_rel_oid;
  		/* Make sure these are OK, too */
  		attr->attstattarget = -1;
  		attr->attcacheoff = -1;
  
  		InsertPgAttributeTuple(rel, attr, indstate);
  
  		/* Add dependency info */
  		myself.classId = RelationRelationId;
  		myself.objectId = new_rel_oid;
  		myself.objectSubId = i + 1;
  		referenced.classId = TypeRelationId;
  		referenced.objectId = attr->atttypid;
  		referenced.objectSubId = 0;
  		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  	}
  
  	/*
  	 * Next we add the system attributes.  Skip OID if rel has no OIDs. Skip
  	 * all for a view or type relation.  We don't bother with making datatype
  	 * dependencies here, since presumably all these types are pinned.
  	 */
  	if (relkind != RELKIND_VIEW && relkind != RELKIND_COMPOSITE_TYPE)
  	{
  		for (i = 0; i < (int) lengthof(SysAtt); i++)
  		{
  			FormData_pg_attribute attStruct;
  
  			/* skip OID where appropriate */
  			if (!tupdesc->tdhasoid &&
  				SysAtt[i]->attnum == ObjectIdAttributeNumber)
  				continue;
  
  			memcpy(&attStruct, (char *) SysAtt[i], sizeof(FormData_pg_attribute));
  
  			/* Fill in the correct relation OID in the copied tuple */
  			attStruct.attrelid = new_rel_oid;
  
  			/* Fill in correct inheritance info for the OID column */
  			if (attStruct.attnum == ObjectIdAttributeNumber)
  			{
  				attStruct.attislocal = oidislocal;
  				attStruct.attinhcount = oidinhcount;
  			}
  
  			InsertPgAttributeTuple(rel, &attStruct, indstate);
  		}
  	}
  
  	/*
  	 * clean up
  	 */
  	CatalogCloseIndexes(indstate);
  
  	heap_close(rel, RowExclusiveLock);
  }
  
  /* --------------------------------
   *		InsertPgClassTuple
   *
   *		Construct and insert a new tuple in pg_class.
   *
   * Caller has already opened and locked pg_class.
   * Tuple data is taken from new_rel_desc->rd_rel, except for the
   * variable-width fields which are not present in a cached reldesc.
   * relacl and reloptions are passed in Datum form (to avoid having
   * to reference the data types in heap.h).	Pass (Datum) 0 to set them
   * to NULL.
   * --------------------------------
   */
  void
  InsertPgClassTuple(Relation pg_class_desc,
  				   Relation new_rel_desc,
  				   Oid new_rel_oid,
  				   Datum relacl,
  				   Datum reloptions)
  {
  	Form_pg_class rd_rel = new_rel_desc->rd_rel;
  	Datum		values[Natts_pg_class];
  	bool		nulls[Natts_pg_class];
  	HeapTuple	tup;
  
  	/* This is a tad tedious, but way cleaner than what we used to do... */
  	memset(values, 0, sizeof(values));
  	memset(nulls, false, sizeof(nulls));
  
  	values[Anum_pg_class_relname - 1] = NameGetDatum(&rd_rel->relname);
  	values[Anum_pg_class_relnamespace - 1] = ObjectIdGetDatum(rd_rel->relnamespace);
  	values[Anum_pg_class_reltype - 1] = ObjectIdGetDatum(rd_rel->reltype);
  	values[Anum_pg_class_reloftype - 1] = ObjectIdGetDatum(rd_rel->reloftype);
  	values[Anum_pg_class_relowner - 1] = ObjectIdGetDatum(rd_rel->relowner);
  	values[Anum_pg_class_relam - 1] = ObjectIdGetDatum(rd_rel->relam);
  	values[Anum_pg_class_relfilenode - 1] = ObjectIdGetDatum(rd_rel->relfilenode);
  	values[Anum_pg_class_reltablespace - 1] = ObjectIdGetDatum(rd_rel->reltablespace);
  	values[Anum_pg_class_relpages - 1] = Int32GetDatum(rd_rel->relpages);
  	values[Anum_pg_class_reltuples - 1] = Float4GetDatum(rd_rel->reltuples);
  	values[Anum_pg_class_reltoastrelid - 1] = ObjectIdGetDatum(rd_rel->reltoastrelid);
  	values[Anum_pg_class_reltoastidxid - 1] = ObjectIdGetDatum(rd_rel->reltoastidxid);
  	values[Anum_pg_class_relhasindex - 1] = BoolGetDatum(rd_rel->relhasindex);
  	values[Anum_pg_class_relisshared - 1] = BoolGetDatum(rd_rel->relisshared);
  	values[Anum_pg_class_relistemp - 1] = BoolGetDatum(rd_rel->relistemp);
  	values[Anum_pg_class_relkind - 1] = CharGetDatum(rd_rel->relkind);
  	values[Anum_pg_class_relstorage - 1] = CharGetDatum(rd_rel->relstorage);
  	values[Anum_pg_class_relnatts - 1] = Int16GetDatum(rd_rel->relnatts);
  	values[Anum_pg_class_relchecks - 1] = Int16GetDatum(rd_rel->relchecks);
  	values[Anum_pg_class_relhasoids - 1] = BoolGetDatum(rd_rel->relhasoids);
  	values[Anum_pg_class_relhaspkey - 1] = BoolGetDatum(rd_rel->relhaspkey);
  	values[Anum_pg_class_relhasexclusion - 1] = BoolGetDatum(rd_rel->relhasexclusion);
  	values[Anum_pg_class_relhasrules - 1] = BoolGetDatum(rd_rel->relhasrules);
  	values[Anum_pg_class_relhastriggers - 1] = BoolGetDatum(rd_rel->relhastriggers);
  	values[Anum_pg_class_relhassubclass - 1] = BoolGetDatum(rd_rel->relhassubclass);
  	values[Anum_pg_class_relfrozenxid - 1] = TransactionIdGetDatum(rd_rel->relfrozenxid);
  	if (relacl != (Datum) 0)
  		values[Anum_pg_class_relacl - 1] = relacl;
  	else
  		nulls[Anum_pg_class_relacl - 1] = true;
  	if (reloptions != (Datum) 0)
  		values[Anum_pg_class_reloptions - 1] = reloptions;
  	else
  		nulls[Anum_pg_class_reloptions - 1] = true;
  
  	tup = heap_form_tuple(RelationGetDescr(pg_class_desc), values, nulls);
  
  	/*
  	 * The new tuple must have the oid already chosen for the rel.	Sure would
  	 * be embarrassing to do this sort of thing in polite company.
  	 */
  	HeapTupleSetOid(tup, new_rel_oid);
  
  	/* finally insert the new tuple, update the indexes, and clean up */
  	simple_heap_insert(pg_class_desc, tup);
  
  	CatalogUpdateIndexes(pg_class_desc, tup);
  
  	heap_freetuple(tup);
  }
  
  /* --------------------------------
   *		AddNewRelationTuple
   *
   *		this registers the new relation in the catalogs by
   *		adding a tuple to pg_class.
   * --------------------------------
   */
  static void
  AddNewRelationTuple(Relation pg_class_desc,
  					Relation new_rel_desc,
  					Oid new_rel_oid,
  					Oid new_type_oid,
  					Oid reloftype,
  					Oid relowner,
  					char relkind,
  					char relstorage,
  					Datum relacl,
  					Datum reloptions)
  {
  	Form_pg_class new_rel_reltup;
  
  	/*
  	 * first we update some of the information in our uncataloged relation's
  	 * relation descriptor.
  	 */
  	new_rel_reltup = new_rel_desc->rd_rel;
  
  	switch (relkind)
  	{
  		case RELKIND_RELATION:
  		case RELKIND_INDEX:
  		case RELKIND_TOASTVALUE:
  		case RELKIND_AOSEGMENTS:
  		case RELKIND_AOBLOCKDIR:
  		case RELKIND_AOVISIMAP:
  			/* The relation is real, but as yet empty */
  			new_rel_reltup->relpages = 0;
  			new_rel_reltup->reltuples = 0;
  
  			/* estimated stats for external tables */
  			/* NOTE: look at cdb_estimate_rel_size() if changing these values */
  			if(relstorage_is_external(relstorage))
  			{
  				new_rel_reltup->relpages = 1000;
  				new_rel_reltup->reltuples = 1000000;
  			}
  			break;
  		case RELKIND_SEQUENCE:
  			/* Sequences always have a known size */
  			new_rel_reltup->relpages = 1;
  			new_rel_reltup->reltuples = 1;
  			break;
  		default:
  			/* Views, etc, have no disk storage */
  			new_rel_reltup->relpages = 0;
  			new_rel_reltup->reltuples = 0;
  			break;
  	}
  
  	/* Initialize relfrozenxid */
  	if (should_have_valid_relfrozenxid(relkind, relstorage))
  	{
  		/*
  		 * Initialize to the minimum XID that could put tuples in the table.
  		 * We know that no xacts older than RecentXmin are still running, so
  		 * that will do.
  		 */
  		new_rel_reltup->relfrozenxid = RecentXmin;
  	}
  	else
  	{
  		/*
  		 * Other relation types will not contain XIDs, so set relfrozenxid to
  		 * InvalidTransactionId.  (Note: a sequence does contain a tuple, but
  		 * we force its xmin to be FrozenTransactionId always; see
  		 * commands/sequence.c.)
  		 */
  		new_rel_reltup->relfrozenxid = InvalidTransactionId;
  	}
  
  	new_rel_reltup->relowner = relowner;
  	new_rel_reltup->reltype = new_type_oid;
  	new_rel_reltup->reloftype = reloftype;
  	new_rel_reltup->relkind = relkind;
  	new_rel_reltup->relstorage = relstorage;
  
  	new_rel_desc->rd_att->tdtypeid = new_type_oid;
  
  	/* Now build and insert the tuple */
  	InsertPgClassTuple(pg_class_desc, new_rel_desc, new_rel_oid,
  					   relacl, reloptions);
  }
  
  
  /* --------------------------------
   *		AddNewRelationType -
   *
   *		define a composite type corresponding to the new relation
   * --------------------------------
   */
  static Oid
  AddNewRelationType(const char *typeName,
  				   Oid typeNamespace,
  				   Oid new_rel_oid,
  				   char new_rel_kind,
  				   Oid ownerid,
  				   Oid new_row_type,
  				   Oid new_array_type)
  {
  	return
  		TypeCreate(new_row_type,	/* optional predetermined OID */
  				   typeName,	/* type name */
  				   typeNamespace,		/* type namespace */
  				   new_rel_oid, /* relation oid */
  				   new_rel_kind,	/* relation kind */
  				   ownerid,		/* owner's ID */
  				   -1,			/* internal size (varlena) */
  				   TYPTYPE_COMPOSITE,	/* type-type (composite) */
  				   TYPCATEGORY_COMPOSITE,		/* type-category (ditto) */
  				   false,		/* composite types are never preferred */
  				   DEFAULT_TYPDELIM,	/* default array delimiter */
  				   F_RECORD_IN, /* input procedure */
  				   F_RECORD_OUT,	/* output procedure */
  				   F_RECORD_RECV,		/* receive procedure */
  				   F_RECORD_SEND,		/* send procedure */
  				   InvalidOid,	/* typmodin procedure - none */
  				   InvalidOid,	/* typmodout procedure - none */
  				   InvalidOid,	/* analyze procedure - default */
  				   InvalidOid,	/* array element type - irrelevant */
  				   false,		/* this is not an array type */
  				   new_array_type,		/* array type if any */
  				   InvalidOid,	/* domain base type - irrelevant */
  				   NULL,		/* default value - none */
  				   NULL,		/* default binary representation */
  				   false,		/* passed by reference */
  				   'd',			/* alignment - must be the largest! */
  				   'x',			/* fully TOASTable */
  				   -1,			/* typmod */
  				   0,			/* array dimensions for typBaseType */
  				   false);		/* Type NOT NULL */
  }
  
  /* --------------------------------
   *		heap_create_with_catalog
   *
   *		creates a new cataloged relation.  see comments above.
   *
   * Arguments:
   *	relname: name to give to new rel
   *	relnamespace: OID of namespace it goes in
   *	reltablespace: OID of tablespace it goes in
   *	relid: OID to assign to new rel, or InvalidOid to select a new OID
   *	reltypeid: OID to assign to rel's rowtype, or InvalidOid to select one
   *	ownerid: OID of new rel's owner
   *	tupdesc: tuple descriptor (source of column definitions)
   *	cooked_constraints: list of precooked check constraints and defaults
   *	relkind: relkind for new rel
   *	shared_relation: TRUE if it's to be a shared relation
   *	mapped_relation: TRUE if the relation will use the relfilenode map
   *	oidislocal: TRUE if oid column (if any) should be marked attislocal
   *	oidinhcount: attinhcount to assign to oid column (if any)
   *	oncommit: ON COMMIT marking (only relevant if it's a temp table)
   *	reloptions: reloptions in Datum form, or (Datum) 0 if none
   *	use_user_acl: TRUE if should look for user-defined default permissions;
   *		if FALSE, relacl is always set NULL
   *	allow_system_table_mods: TRUE to allow creation in system namespaces
   *
   * Returns the OID of the new relation
   * --------------------------------
   */
  Oid
  heap_create_with_catalog(const char *relname,
  						 Oid relnamespace,
  						 Oid reltablespace,
  						 Oid relid,
  						 Oid reltypeid,
  						 Oid reloftypeid,
  						 Oid ownerid,
  						 TupleDesc tupdesc,
  						 List *cooked_constraints,
  						 Oid relam,
  						 char relkind,
  						 char relstorage,
  						 bool shared_relation,
  						 bool mapped_relation,
  						 bool oidislocal,
  						 int oidinhcount,
  						 OnCommitAction oncommit,
                           const struct GpPolicy *policy,
  						 Datum reloptions,
  						 bool use_user_acl,
  						 bool allow_system_table_mods,
  						 bool valid_opts)
  {
  	Relation	pg_class_desc;
  	Relation	new_rel_desc;
  	Acl		   *relacl;
  	Oid			old_type_oid;
  	Oid			new_type_oid;
  	Oid			new_array_oid = InvalidOid;
  	bool		appendOnlyRel;
  	StdRdOptions *stdRdOptions;
  	int			safefswritesize = gp_safefswritesize;
  	char	   *relarrayname = NULL;
  
  	pg_class_desc = heap_open(RelationRelationId, RowExclusiveLock);
  
  	/*
  	 * sanity checks
  	 */
  	Assert(IsNormalProcessingMode() || IsBootstrapProcessingMode());
  
  	/*
  	 * Was "appendonly" specified in the relopts? If yes, fix our relstorage.
  	 * Also, check for override (debug) GUCs.
  	 */
  	if (relkind == RELKIND_RELATION)
  	{
  		stdRdOptions = (StdRdOptions*) heap_reloptions(
  			relkind, reloptions, !valid_opts);
  		appendOnlyRel = stdRdOptions->appendonly;
  		validateAppendOnlyRelOptions(appendOnlyRel,
  									 stdRdOptions->blocksize,
  									 safefswritesize,
  									 stdRdOptions->compresslevel,
  									 stdRdOptions->compresstype,
  									 stdRdOptions->checksum,
  									 relkind,
  									 stdRdOptions->columnstore);
  		if(appendOnlyRel)
  		{
  			if(stdRdOptions->columnstore)
  				relstorage = RELSTORAGE_AOCOLS;
  			else
  				relstorage = RELSTORAGE_AOROWS;
  			reloptions = transformAOStdRdOptions(stdRdOptions, reloptions);
  		}
  	}
  	else
  		appendOnlyRel = false;
  
  	/*
  	 * MPP-8058: disallow OIDS on column-oriented tables.
  	 */
  	if (tupdesc->tdhasoid && relstorage == RELSTORAGE_AOCOLS)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("OIDS=TRUE is not allowed on tables that use column-oriented storage. Use OIDS=FALSE")));
  
  	CheckAttributeNamesTypes(tupdesc, relkind, allow_system_table_mods);
  
  	if (get_relname_relid(relname, relnamespace))
  		ereport(ERROR,
  				(errcode(ERRCODE_DUPLICATE_TABLE),
  				 errmsg("relation \"%s\" already exists", relname)));
  
  	/*
  	 * Since we are going to create a rowtype as well, also check for
  	 * collision with an existing type name.  If there is one and it's an
  	 * autogenerated array, we can rename it out of the way; otherwise we can
  	 * at least give a good error message.
  	 */
  	old_type_oid = GetSysCacheOid2(TYPENAMENSP,
  								   CStringGetDatum(relname),
  								   ObjectIdGetDatum(relnamespace));
  	if (OidIsValid(old_type_oid))
  	{
  		if (!moveArrayTypeName(old_type_oid, relname, relnamespace))
  			ereport(ERROR,
  					(errcode(ERRCODE_DUPLICATE_OBJECT),
  					 errmsg("type \"%s\" already exists", relname),
  			   errhint("A relation has an associated type of the same name, "
  					   "so you must use a name that doesn't conflict "
  					   "with any existing type.")));
  	}
  
  	/*
  	 * Shared relations must be in pg_global (last-ditch check)
  	 */
  	if (shared_relation && reltablespace != GLOBALTABLESPACE_OID)
  		elog(ERROR, "shared relations must be placed in pg_global tablespace");
  
  	/*
  	 * Get preassigned OID for GP_ROLE_EXECUTE or binary upgrade
  	 */
  	if (!OidIsValid(relid) && (Gp_role == GP_ROLE_EXECUTE || IsBinaryUpgrade))
  		relid = GetPreassignedOidForRelation(relnamespace, relname);
  
  	/*
  	 * GP_ROLE_DISPATCH and GP_ROLE_UTILITY do not have preassigned OIDs.
  	 * Allocate new OIDs here.
  	 *
  	 * For sequence relations, the relfilenode has to be the same as OID.
  	 * To accomplish this, we have a special function GetSequenceRelationOid
  	 * which locks both the Oid and relfilenode counter, syncs them, and
  	 * allocates the synced value to here.
  	 */
  	if (!OidIsValid(relid) && Gp_role != GP_ROLE_EXECUTE)
  	{
  		if (IsBootstrapProcessingMode())
  			relid = GetNewOid(pg_class_desc);
  		else if (relkind == RELKIND_SEQUENCE)
  			relid = GetNewSequenceRelationOid(pg_class_desc);
  		else
  			relid = GetNewOid(pg_class_desc);
  	}
  
  	/*
  	 * Determine the relation's initial permissions.
  	 */
  	if (use_user_acl)
  	{
  		switch (relkind)
  		{
  			case RELKIND_RELATION:
  			case RELKIND_VIEW:
  				relacl = get_user_default_acl(ACL_OBJECT_RELATION, ownerid,
  											  relnamespace);
  				break;
  			case RELKIND_SEQUENCE:
  				relacl = get_user_default_acl(ACL_OBJECT_SEQUENCE, ownerid,
  											  relnamespace);
  				break;
  			default:
  				relacl = NULL;
  				break;
  		}
  	}
  	else
  		relacl = NULL;
  
  	/*
  	 * Create the relcache entry (mostly dummy at this point) and the physical
  	 * disk file.  (If we fail further down, it's the smgr's responsibility to
  	 * remove the disk file again.)
  	 */
  	new_rel_desc = heap_create(relname,
  							   relnamespace,
  							   reltablespace,
  							   relid,
  							   tupdesc,
  							   relam,
  							   relkind,
  							   relstorage,
  							   shared_relation,
  							   mapped_relation,
  							   allow_system_table_mods);
  
  	Assert(relid == RelationGetRelid(new_rel_desc));
  
  	/*
  	 * Decide whether to create an array type over the relation's rowtype. We
  	 * do not create any array types for system catalogs (ie, those made
  	 * during initdb).	We create array types for regular relations, views,
  	 * and composite types ... but not, eg, for toast tables or sequences.
  	 *
  	 * Also not for the auxiliary heaps created for bitmap indexes or append-
  	 * only tables.
  	 */
  	if (IsUnderPostmaster && ((relkind == RELKIND_RELATION && !appendOnlyRel) ||
  							  relkind == RELKIND_VIEW ||
  							  relkind == RELKIND_COMPOSITE_TYPE) &&
  		relnamespace != PG_BITMAPINDEX_NAMESPACE)
  	{
  		/* OK, so pre-assign a type OID for the array type */
  		Relation	pg_type = heap_open(TypeRelationId, AccessShareLock);
  
  		relarrayname = makeArrayTypeName(relname, relnamespace);
  
  		/*
  		 * If we are expected to get a preassigned Oid but receive InvalidOid,
  		 * get a new Oid. This can happen during upgrades from GPDB4 to 5 where
  		 * array types over relation rowtypes were introduced so there are no
  		 * pre-existing array types to dump from the old cluster
  		 */
  		if (Gp_role == GP_ROLE_EXECUTE || IsBinaryUpgrade)
  		{
  			new_array_oid = GetPreassignedOidForType(relnamespace, relarrayname);
  
  			if (new_array_oid == InvalidOid && IsBinaryUpgrade)
  				new_array_oid = GetNewOid(pg_type);
  		}
  		else
  			new_array_oid = GetNewOid(pg_type);
  		heap_close(pg_type, AccessShareLock);
  	}
  
  	/*
  	 * Since defining a relation also defines a complex type, we add a new
  	 * system type corresponding to the new relation.  The OID of the type can
  	 * be preselected by the caller, but if reltypeid is InvalidOid, we'll
  	 * generate a new OID for it.
  	 *
  	 * NOTE: we could get a unique-index failure here, in case someone else is
  	 * creating the same type name in parallel but hadn't committed yet when
  	 * we checked for a duplicate name above.
  	 */
  	new_type_oid = AddNewRelationType(relname,
  									  relnamespace,
  									  relid,
  									  relkind,
  									  ownerid,
  									  reltypeid,
  									  new_array_oid);
  
  	/*
  	 * Now make the array type if wanted.
  	 */
  	if (OidIsValid(new_array_oid))
  	{
  		if (!relarrayname)
  			relarrayname = makeArrayTypeName(relname, relnamespace);
  
  		TypeCreate(new_array_oid,		/* force the type's OID to this */
  				   relarrayname,	/* Array type name */
  				   relnamespace,	/* Same namespace as parent */
  				   InvalidOid,	/* Not composite, no relationOid */
  				   0,			/* relkind, also N/A here */
  				   ownerid,		/* owner's ID */
  				   -1,			/* Internal size (varlena) */
  				   TYPTYPE_BASE,	/* Not composite - typelem is */
  				   TYPCATEGORY_ARRAY,	/* type-category (array) */
  				   false,		/* array types are never preferred */
  				   DEFAULT_TYPDELIM,	/* default array delimiter */
  				   F_ARRAY_IN,	/* array input proc */
  				   F_ARRAY_OUT, /* array output proc */
  				   F_ARRAY_RECV,	/* array recv (bin) proc */
  				   F_ARRAY_SEND,	/* array send (bin) proc */
  				   InvalidOid,	/* typmodin procedure - none */
  				   InvalidOid,	/* typmodout procedure - none */
  				   InvalidOid,	/* analyze procedure - default */
  				   new_type_oid,	/* array element type - the rowtype */
  				   true,		/* yes, this is an array type */
  				   InvalidOid,	/* this has no array type */
  				   InvalidOid,	/* domain base type - irrelevant */
  				   NULL,		/* default value - none */
  				   NULL,		/* default binary representation */
  				   false,		/* passed by reference */
  				   'd',			/* alignment - must be the largest! */
  				   'x',			/* fully TOASTable */
  				   -1,			/* typmod */
  				   0,			/* array dimensions for typBaseType */
  				   false);		/* Type NOT NULL */
  
  		pfree(relarrayname);
  	}
  
  	/*
  	 * now create an entry in pg_class for the relation.
  	 *
  	 * NOTE: we could get a unique-index failure here, in case someone else is
  	 * creating the same relation name in parallel but hadn't committed yet
  	 * when we checked for a duplicate name above.
  	 */
  	AddNewRelationTuple(pg_class_desc,
  						new_rel_desc,
  						relid,
  						new_type_oid,
  						reloftypeid,
  						ownerid,
  						relkind,
  						relstorage,
  						PointerGetDatum(relacl),
  						reloptions);
  
  	/*
  	 * if this is an append-only relation, add an entry in pg_appendonly.
  	 */
  	if(appendOnlyRel)
  	{
  		InsertAppendOnlyEntry(relid,
  							  stdRdOptions->blocksize,
  							  safefswritesize,
  							  stdRdOptions->compresslevel,
  							  stdRdOptions->checksum,
                                stdRdOptions->columnstore,
  							  stdRdOptions->compresstype,
  							  InvalidOid,
  							  InvalidOid,
  							  InvalidOid,
  							  InvalidOid,
  							  InvalidOid);
  	}
  
  
  	/*
  	 * now add tuples to pg_attribute for the attributes in our new relation.
  	 */
  	AddNewAttributeTuples(relid, new_rel_desc->rd_att, relkind,
  						  oidislocal, oidinhcount);
  
  	/*
  	 * Make a dependency link to force the relation to be deleted if its
  	 * namespace is.  Also make a dependency link to its owner, as well as
  	 * dependencies for any roles mentioned in the default ACL.
  	 *
  	 * For composite types, these dependencies are tracked for the pg_type
  	 * entry, so we needn't record them here.  Likewise, TOAST tables don't
  	 * need a namespace dependency (they live in a pinned namespace) nor an
  	 * owner dependency (they depend indirectly through the parent table), nor
  	 * should they have any ACL entries.
  	 *
  	 * Also, skip this in bootstrap mode, since we don't make dependencies
  	 * while bootstrapping.
  	 */
  	if (relkind != RELKIND_COMPOSITE_TYPE &&
  		relkind != RELKIND_TOASTVALUE &&
  		!IsBootstrapProcessingMode())
  	{
  		ObjectAddress myself,
  					referenced;
  
  		myself.classId = RelationRelationId;
  		myself.objectId = relid;
  		myself.objectSubId = 0;
  		referenced.classId = NamespaceRelationId;
  		referenced.objectId = relnamespace;
  		referenced.objectSubId = 0;
  		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  
  		recordDependencyOnOwner(RelationRelationId, relid, ownerid);
  		recordDependencyOnCurrentExtension(&myself, false);
  
  		if (reloftypeid)
  		{
  			referenced.classId = TypeRelationId;
  			referenced.objectId = reloftypeid;
  			referenced.objectSubId = 0;
  			recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
  		}
  
  		if (relacl != NULL)
  		{
  			int			nnewmembers;
  			Oid		   *newmembers;
  
  			nnewmembers = aclmembers(relacl, &newmembers);
  			updateAclDependencies(RelationRelationId, relid, 0,
  								  ownerid,
  								  0, NULL,
  								  nnewmembers, newmembers);
  		}
  	}
  
  	/*
  	 * Store any supplied constraints and defaults.
  	 *
  	 * NB: this may do a CommandCounterIncrement and rebuild the relcache
  	 * entry, so the relation must be valid and self-consistent at this point.
  	 * In particular, there are not yet constraints and defaults anywhere.
  	 */
  	StoreConstraints(new_rel_desc, cooked_constraints);
  
  	/*
  	 * If there's a special on-commit action, remember it
  	 */
  	if (oncommit != ONCOMMIT_NOOP)
  		register_on_commit_action(relid, oncommit);
  
  	/*
       * CDB: If caller gave us a distribution policy, store the distribution
       * key column list in the gp_distribution_policy catalog and attach a
       * copy to the relcache entry.
       */
      if (policy && (Gp_role == GP_ROLE_DISPATCH || IsBinaryUpgrade))
      {
          Assert(relkind == RELKIND_RELATION);
          new_rel_desc->rd_cdbpolicy = GpPolicyCopy(GetMemoryChunkContext(new_rel_desc), policy);
          GpPolicyStore(relid, policy);
      }
  
  	if (Gp_role == GP_ROLE_DISPATCH) /* MPP-11313: */
  	{
  		bool doIt = true;
  		char *subtyp = "TABLE";
  
  		switch (relkind)
  		{
  			case RELKIND_RELATION:
  				break;
  			case RELKIND_INDEX:
  				subtyp = "INDEX";
  				break;
  			case RELKIND_SEQUENCE:
  				subtyp = "SEQUENCE";
  				break;
  			case RELKIND_VIEW:
  				subtyp = "VIEW";
  				break;
  			default:
  				doIt = false;
  		}
  
  		/* MPP-7576: don't track internal namespace tables */
  		switch (relnamespace) 
  		{
  			case PG_CATALOG_NAMESPACE:
  				/* MPP-7773: don't track objects in system namespace
  				 * if modifying system tables (eg during upgrade)  
  				 */
  				if (allowSystemTableModsDDL)
  					doIt = false;
  				break;
  
  			case PG_TOAST_NAMESPACE:
  			case PG_BITMAPINDEX_NAMESPACE:
  			case PG_AOSEGMENT_NAMESPACE:
  				doIt = false;
  				break;
  			default:
  				break;
  		}
  
  		/* MPP-7572: not valid if in any temporary namespace */
  		if (doIt)
  			doIt = (!(isAnyTempNamespace(relnamespace)));
  
  		/* MPP-6929: metadata tracking */
  		if (doIt)
  			MetaTrackAddObject(RelationRelationId,
  							   relid, GetUserId(), /* not ownerid */
  							   "CREATE", subtyp
  					);
  	}
  
  	/*
  	 * ok, the relation has been cataloged, so close our relations and return
  	 * the OID of the newly created relation.
  	 */
  	heap_close(new_rel_desc, NoLock);	/* do not unlock till end of xact */
  	heap_close(pg_class_desc, RowExclusiveLock);
  
  	return relid;
  }
  
  
  /*
   *		RelationRemoveInheritance
   *
   * Formerly, this routine checked for child relations and aborted the
   * deletion if any were found.	Now we rely on the dependency mechanism
   * to check for or delete child relations.	By the time we get here,
   * there are no children and we need only remove any pg_inherits rows
   * linking this relation to its parent(s).
   */
  static void
  RelationRemoveInheritance(Oid relid)
  {
  	Relation	catalogRelation;
  	SysScanDesc scan;
  	ScanKeyData key;
  	HeapTuple	tuple;
  
  	catalogRelation = heap_open(InheritsRelationId, RowExclusiveLock);
  
  	ScanKeyInit(&key,
  				Anum_pg_inherits_inhrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  
  	scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId, true,
  							  SnapshotNow, 1, &key);
  
  	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
  		simple_heap_delete(catalogRelation, &tuple->t_self);
  
  	systable_endscan(scan);
  	heap_close(catalogRelation, RowExclusiveLock);
  }
  
  static void
  RemovePartitioning(Oid relid)
  {
  	Relation rel;
  	SysScanDesc scan;
  	ScanKeyData key;
  	HeapTuple tuple;
  	Relation pgrule;
  
  	if (Gp_role == GP_ROLE_EXECUTE)
  		return;
  
  	RemovePartitionEncodingByRelid(relid);
  
  	/* loop through all matches in pg_partition */
  	rel = heap_open(PartitionRelationId, RowExclusiveLock);
  	pgrule = heap_open(PartitionRuleRelationId,
  					   RowExclusiveLock);
  
  	ScanKeyInit(&key,
  				Anum_pg_partition_parrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  
  	scan = systable_beginscan(rel, PartitionParrelidIndexId, true,
  							  SnapshotNow, 1, &key);
  	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
  	{
  		Oid			paroid = HeapTupleGetOid(tuple);
  		SysScanDesc rule_scan;
  		ScanKeyData rule_key;
  		HeapTuple	rule_tuple;
  
  		/* remove all rows for pg_partition_rule */
  		ScanKeyInit(&rule_key,
  					Anum_pg_partition_rule_paroid,
  					BTEqualStrategyNumber, F_OIDEQ,
  					ObjectIdGetDatum(paroid));
  		rule_scan = systable_beginscan(pgrule, PartitionRuleParoidParparentruleParruleordIndexId, true,
  									   SnapshotNow, 1, &rule_key);
  		while (HeapTupleIsValid(rule_tuple = systable_getnext(rule_scan)))
  			simple_heap_delete(pgrule, &rule_tuple->t_self);
  		systable_endscan(rule_scan);
  
  		/* remove ourself */
  		simple_heap_delete(rel, &tuple->t_self);
  	}
  	systable_endscan(scan);
  	heap_close(rel, NoLock);
  
  	/* we might be a leaf partition: delete any records */
  
  	ScanKeyInit(&key,
  				Anum_pg_partition_rule_parchildrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  
  	scan = systable_beginscan(pgrule, PartitionRuleParchildrelidIndexId, true,
  							  SnapshotNow, 1, &key);
  	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
  		simple_heap_delete(pgrule, &tuple->t_self);
  	systable_endscan(scan);
  	heap_close(pgrule, NoLock);
  
  	CommandCounterIncrement();
  }
  
  /*
   *		DeleteRelationTuple
   *
   * Remove pg_class row for the given relid.
   *
   * Note: this is shared by relation deletion and index deletion.  It's
   * not intended for use anyplace else.
   */
  void
  DeleteRelationTuple(Oid relid)
  {
  	Relation	pg_class_desc;
  	HeapTuple	tup;
  
  	/* Grab an appropriate lock on the pg_class relation */
  	pg_class_desc = heap_open(RelationRelationId, RowExclusiveLock);
  
  	tup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
  	if (!HeapTupleIsValid(tup))
  		elog(ERROR, "cache lookup failed for relation %u", relid);
  
  	/* delete the relation tuple from pg_class, and finish up */
  	simple_heap_delete(pg_class_desc, &tup->t_self);
  
  	ReleaseSysCache(tup);
  
  	heap_close(pg_class_desc, RowExclusiveLock);
  }
  
  /*
   *		DeleteAttributeTuples
   *
   * Remove pg_attribute rows for the given relid.
   *
   * Note: this is shared by relation deletion and index deletion.  It's
   * not intended for use anyplace else.
   */
  void
  DeleteAttributeTuples(Oid relid)
  {
  	Relation	attrel;
  	SysScanDesc scan;
  	ScanKeyData key[1];
  	HeapTuple	atttup;
  
  	/* Grab an appropriate lock on the pg_attribute relation */
  	attrel = heap_open(AttributeRelationId, RowExclusiveLock);
  
  	/* Use the index to scan only attributes of the target relation */
  	ScanKeyInit(&key[0],
  				Anum_pg_attribute_attrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  
  	scan = systable_beginscan(attrel, AttributeRelidNumIndexId, true,
  							  SnapshotNow, 1, key);
  
  	/* Delete all the matching tuples */
  	while ((atttup = systable_getnext(scan)) != NULL)
  		simple_heap_delete(attrel, &atttup->t_self);
  
  	/* Clean up after the scan */
  	systable_endscan(scan);
  	heap_close(attrel, RowExclusiveLock);
  }
  
  /*
   *		RemoveAttributeById
   *
   * This is the guts of ALTER TABLE DROP COLUMN: actually mark the attribute
   * deleted in pg_attribute.  We also remove pg_statistic entries for it.
   * (Everything else needed, such as getting rid of any pg_attrdef entry,
   * is handled by dependency.c.)
   */
  void
  RemoveAttributeById(Oid relid, AttrNumber attnum)
  {
  	Relation	rel;
  	Relation	attr_rel;
  	HeapTuple	tuple;
  	Form_pg_attribute attStruct;
  	char		newattname[NAMEDATALEN];
  
  	/*
  	 * Grab an exclusive lock on the target table, which we will NOT release
  	 * until end of transaction.  (In the simple case where we are directly
  	 * dropping this column, AlterTableDropColumn already did this ... but
  	 * when cascading from a drop of some other object, we may not have any
  	 * lock.)
  	 */
  	rel = relation_open(relid, AccessExclusiveLock);
  
  	attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);
  
  	tuple = SearchSysCacheCopy2(ATTNUM,
  								ObjectIdGetDatum(relid),
  								Int16GetDatum(attnum));
  	if (!HeapTupleIsValid(tuple))		/* shouldn't happen */
  		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
  			 attnum, relid);
  	attStruct = (Form_pg_attribute) GETSTRUCT(tuple);
  
  	if (attnum < 0)
  	{
  		/* System attribute (probably OID) ... just delete the row */
  
  		simple_heap_delete(attr_rel, &tuple->t_self);
  	}
  	else
  	{
  		/* Dropping user attributes is lots harder */
  
  		/* Mark the attribute as dropped */
  		attStruct->attisdropped = true;
  
  		/*
  		 * Set the type OID to invalid.  A dropped attribute's type link
  		 * cannot be relied on (once the attribute is dropped, the type might
  		 * be too). Fortunately we do not need the type row --- the only
  		 * really essential information is the type's typlen and typalign,
  		 * which are preserved in the attribute's attlen and attalign.  We set
  		 * atttypid to zero here as a means of catching code that incorrectly
  		 * expects it to be valid.
  		 */
  		attStruct->atttypid = InvalidOid;
  
  		/* Remove any NOT NULL constraint the column may have */
  		attStruct->attnotnull = false;
  
  		/* We don't want to keep stats for it anymore */
  		attStruct->attstattarget = 0;
  
  		/*
  		 * Change the column name to something that isn't likely to conflict
  		 */
  		snprintf(newattname, sizeof(newattname),
  				 "........pg.dropped.%d........", attnum);
  		namestrcpy(&(attStruct->attname), newattname);
  
  		simple_heap_update(attr_rel, &tuple->t_self, tuple);
  
  		/* keep the system catalog indexes current */
  		CatalogUpdateIndexes(attr_rel, tuple);
  	}
  
  	/*
  	 * Because updating the pg_attribute row will trigger a relcache flush for
  	 * the target relation, we need not do anything else to notify other
  	 * backends of the change.
  	 */
  
  	heap_close(attr_rel, RowExclusiveLock);
  
  	if (attnum > 0)
  		RemoveStatistics(relid, attnum);
  
  	relation_close(rel, NoLock);
  }
  
  /*
   *		RemoveAttrDefault
   *
   * If the specified relation/attribute has a default, remove it.
   * (If no default, raise error if complain is true, else return quietly.)
   */
  void
  RemoveAttrDefault(Oid relid, AttrNumber attnum,
  				  DropBehavior behavior, bool complain)
  {
  	Relation	attrdef_rel;
  	ScanKeyData scankeys[2];
  	SysScanDesc scan;
  	HeapTuple	tuple;
  	bool		found = false;
  
  	attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
  
  	ScanKeyInit(&scankeys[0],
  				Anum_pg_attrdef_adrelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  	ScanKeyInit(&scankeys[1],
  				Anum_pg_attrdef_adnum,
  				BTEqualStrategyNumber, F_INT2EQ,
  				Int16GetDatum(attnum));
  
  	scan = systable_beginscan(attrdef_rel, AttrDefaultIndexId, true,
  							  SnapshotNow, 2, scankeys);
  
  	/* There should be at most one matching tuple, but we loop anyway */
  	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
  	{
  		ObjectAddress object;
  
  		object.classId = AttrDefaultRelationId;
  		object.objectId = HeapTupleGetOid(tuple);
  		object.objectSubId = 0;
  
  		performDeletion(&object, behavior);
  
  		found = true;
  	}
  
  	systable_endscan(scan);
  	heap_close(attrdef_rel, RowExclusiveLock);
  
  	if (complain && !found)
  		elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
  			 relid, attnum);
  }
  
  /*
   *		RemoveAttrDefaultById
   *
   * Remove a pg_attrdef entry specified by OID.	This is the guts of
   * attribute-default removal.  Note it should be called via performDeletion,
   * not directly.
   */
  void
  RemoveAttrDefaultById(Oid attrdefId)
  {
  	Relation	attrdef_rel;
  	Relation	attr_rel;
  	Relation	myrel;
  	ScanKeyData scankeys[1];
  	SysScanDesc scan;
  	HeapTuple	tuple;
  	Oid			myrelid;
  	AttrNumber	myattnum;
  
  	/* Grab an appropriate lock on the pg_attrdef relation */
  	attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
  
  	/* Find the pg_attrdef tuple */
  	ScanKeyInit(&scankeys[0],
  				ObjectIdAttributeNumber,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(attrdefId));
  
  	scan = systable_beginscan(attrdef_rel, AttrDefaultOidIndexId, true,
  							  SnapshotNow, 1, scankeys);
  
  	tuple = systable_getnext(scan);
  	if (!HeapTupleIsValid(tuple))
  		elog(ERROR, "could not find tuple for attrdef %u", attrdefId);
  
  	myrelid = ((Form_pg_attrdef) GETSTRUCT(tuple))->adrelid;
  	myattnum = ((Form_pg_attrdef) GETSTRUCT(tuple))->adnum;
  
  	/* Get an exclusive lock on the relation owning the attribute */
  	myrel = relation_open(myrelid, AccessExclusiveLock);
  
  	/* Now we can delete the pg_attrdef row */
  	simple_heap_delete(attrdef_rel, &tuple->t_self);
  
  	systable_endscan(scan);
  	heap_close(attrdef_rel, RowExclusiveLock);
  
  	/* Fix the pg_attribute row */
  	attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);
  
  	tuple = SearchSysCacheCopy2(ATTNUM,
  								ObjectIdGetDatum(myrelid),
  								Int16GetDatum(myattnum));
  	if (!HeapTupleIsValid(tuple))		/* shouldn't happen */
  		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
  			 myattnum, myrelid);
  
  	((Form_pg_attribute) GETSTRUCT(tuple))->atthasdef = false;
  
  	simple_heap_update(attr_rel, &tuple->t_self, tuple);
  
  	/* keep the system catalog indexes current */
  	CatalogUpdateIndexes(attr_rel, tuple);
  
  	/*
  	 * Our update of the pg_attribute row will force a relcache rebuild, so
  	 * there's nothing else to do here.
  	 */
  	heap_close(attr_rel, RowExclusiveLock);
  
  	/* Keep lock on attribute's rel until end of xact */
  	relation_close(myrel, NoLock);
  }
  
  /*
   * heap_drop_with_catalog	- removes specified relation from catalogs
   *
   * Note that this routine is not responsible for dropping objects that are
   * linked to the pg_class entry via dependencies (for example, indexes and
   * constraints).  Those are deleted by the dependency-tracing logic in
   * dependency.c before control gets here.  In general, therefore, this routine
   * should never be called directly; go through performDeletion() instead.
   */
  void
  heap_drop_with_catalog(Oid relid)
  {
  	Relation	rel;
  	bool		is_part_child = false;
  	bool		is_appendonly_rel;
  	bool		is_external_rel;
  	char		relkind;
  
  	/*
  	 * Open and lock the relation.
  	 */
  	rel = relation_open(relid, AccessExclusiveLock);
  
  	relkind = rel->rd_rel->relkind;
  
  	is_appendonly_rel = (RelationIsAoRows(rel) || RelationIsAoCols(rel));
  	is_external_rel = RelationIsExternal(rel);
  
  	/*
  	 * There can no longer be anyone *else* touching the relation, but we
  	 * might still have open queries or cursors, or pending trigger events,
  	 * in our own session.
  	 */
  	CheckTableNotInUse(rel, "DROP TABLE");
  
  	/*
  	 * There can no longer be anyone *else* touching the relation, but we
  	 * might still have open queries or cursors in our own session.
  	 */
  	if (rel->rd_refcnt != 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_OBJECT_IN_USE),
  				 errmsg("cannot drop \"%s\" because "
  						"it is being used by active queries in this session",
  						RelationGetRelationName(rel))));
  
  	/*
  	 * Schedule unlinking of the relation's physical files at commit.
  	 */
  	if (relkind != RELKIND_VIEW &&
  		relkind != RELKIND_COMPOSITE_TYPE &&
  		!RelationIsExternal(rel))
  	{
  		RelationDropStorage(rel);
  	}
  
  	/*
  	 * Close relcache entry, but *keep* AccessExclusiveLock (unless this is
  	 * a child partition) on the relation until transaction commit.  This
  	 * ensures no one else will try to do something with the doomed relation.
  	 */
  	is_part_child = !rel_needs_long_lock(RelationGetRelid(rel));
  	if (is_part_child)
  		relation_close(rel, AccessExclusiveLock);
  	else
  		relation_close(rel, NoLock);
  
  	/*
  	 * Forget any ON COMMIT action for the rel
  	 */
  	remove_on_commit_action(relid);
  
  	/*
  	 * Flush the relation from the relcache.  We want to do this before
  	 * starting to remove catalog entries, just to be certain that no relcache
  	 * entry rebuild will happen partway through.  (That should not really
  	 * matter, since we don't do CommandCounterIncrement here, but let's be
  	 * safe.)
  	 */
  	RelationForgetRelation(relid);
  
  	/*
  	 * remove inheritance information
  	 */
  	RelationRemoveInheritance(relid);
  
  	/*
  	 * remove partitioning configuration
  	 */
  	RemovePartitioning(relid);
  
  	/*
  	 * delete statistics
  	 */
  	RemoveStatistics(relid, 0);
  
  	/*
  	 * delete attribute tuples
  	 */
  	DeleteAttributeTuples(relid);
  
  	/*
  	 * delete relation tuple
  	 */
  	DeleteRelationTuple(relid);
  
  	/*
  	 * delete error log file
  	 */
  	ErrorLogDelete(MyDatabaseId, relid);
  
  	/*
  	 * append-only table? delete the corresponding pg_appendonly tuple
  	 */
  	if(is_appendonly_rel)
  		RemoveAppendonlyEntry(relid);
  
  	/*
  	 * External table? If so, delete the pg_exttable tuple.
  	 */
  	if (is_external_rel)
  		RemoveExtTableEntry(relid);
  
  	/*
  	 * Remove distribution policy, if any.
   	 */
  	if (relkind == RELKIND_RELATION)
  		GpPolicyRemove(relid);
  
  	/*
  	 * Attribute encoding
  	 */
  	if (relkind == RELKIND_RELATION)
  		RemoveAttributeEncodingsByRelid(relid);
  
  	/* MPP-6929: metadata tracking */
  	MetaTrackDropObject(RelationRelationId,
  						relid);
  
  }
  
  
  /*
   * Store a default expression for column attnum of relation rel.
   */
  void
  StoreAttrDefault(Relation rel, AttrNumber attnum, Node *expr)
  {
  	char	   *adbin;
  	char	   *adsrc;
  	Relation	adrel;
  	HeapTuple	tuple;
  	Datum		values[4];
  	static bool nulls[4] = {false, false, false, false};
  	Relation	attrrel;
  	HeapTuple	atttup;
  	Form_pg_attribute attStruct;
  	Oid			attrdefOid;
  	ObjectAddress colobject,
  				defobject;
  
  	/*
  	 * Flatten expression to string form for storage.
  	 */
  	adbin = nodeToString(expr);
  
  	/*
  	 * Also deparse it to form the mostly-obsolete adsrc field.
  	 */
  	adsrc = deparse_expression(expr,
  							deparse_context_for(RelationGetRelationName(rel),
  												RelationGetRelid(rel)),
  							   false, false);
  
  	/*
  	 * Make the pg_attrdef entry.
  	 */
  	values[Anum_pg_attrdef_adrelid - 1] = RelationGetRelid(rel);
  	values[Anum_pg_attrdef_adnum - 1] = attnum;
  	values[Anum_pg_attrdef_adbin - 1] = CStringGetTextDatum(adbin);
  	values[Anum_pg_attrdef_adsrc - 1] = CStringGetTextDatum(adsrc);
  
  	adrel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
  
  	tuple = heap_form_tuple(adrel->rd_att, values, nulls);
  	attrdefOid = simple_heap_insert(adrel, tuple);
  
  	CatalogUpdateIndexes(adrel, tuple);
  
  	defobject.classId = AttrDefaultRelationId;
  	defobject.objectId = attrdefOid;
  	defobject.objectSubId = 0;
  
  	heap_close(adrel, RowExclusiveLock);
  
  	/* now can free some of the stuff allocated above */
  	pfree(DatumGetPointer(values[Anum_pg_attrdef_adbin - 1]));
  	pfree(DatumGetPointer(values[Anum_pg_attrdef_adsrc - 1]));
  	heap_freetuple(tuple);
  	pfree(adbin);
  	pfree(adsrc);
  
  	/*
  	 * Update the pg_attribute entry for the column to show that a default
  	 * exists.
  	 */
  	attrrel = heap_open(AttributeRelationId, RowExclusiveLock);
  	atttup = SearchSysCacheCopy2(ATTNUM,
  								 ObjectIdGetDatum(RelationGetRelid(rel)),
  								 Int16GetDatum(attnum));
  	if (!HeapTupleIsValid(atttup))
  		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
  			 attnum, RelationGetRelid(rel));
  	attStruct = (Form_pg_attribute) GETSTRUCT(atttup);
  	if (!attStruct->atthasdef)
  	{
  		attStruct->atthasdef = true;
  		simple_heap_update(attrrel, &atttup->t_self, atttup);
  		/* keep catalog indexes current */
  		CatalogUpdateIndexes(attrrel, atttup);
  	}
  	heap_close(attrrel, RowExclusiveLock);
  	heap_freetuple(atttup);
  
  	/*
  	 * Make a dependency so that the pg_attrdef entry goes away if the column
  	 * (or whole table) is deleted.
  	 */
  	colobject.classId = RelationRelationId;
  	colobject.objectId = RelationGetRelid(rel);
  	colobject.objectSubId = attnum;
  
  	recordDependencyOn(&defobject, &colobject, DEPENDENCY_AUTO);
  
  	/*
  	 * Record dependencies on objects used in the expression, too.
  	 */
  	recordDependencyOnExpr(&defobject, expr, NIL, DEPENDENCY_NORMAL);
  }
  
  /*
   * Store a check-constraint expression for the given relation.
   *
   * Caller is responsible for updating the count of constraints
   * in the pg_class entry for the relation.
   */
  static void
  StoreRelCheck(Relation rel, char *ccname, Node *expr,
  			  bool is_local, int inhcount)
  {
  	char	   *ccbin;
  	char	   *ccsrc;
  	List	   *varList;
  	int			keycount;
  	int16	   *attNos;
  
  	/*
  	 * Flatten expression to string form for storage.
  	 */
  	ccbin = nodeToString(expr);
  
  	/*
  	 * Also deparse it to form the mostly-obsolete consrc field.
  	 */
  	ccsrc = deparse_expression(expr,
  							deparse_context_for(RelationGetRelationName(rel),
  												RelationGetRelid(rel)),
  							   false, false);
  
  	/*
  	 * Find columns of rel that are used in expr
  	 *
  	 * NB: pull_var_clause is okay here only because we don't allow subselects
  	 * in check constraints; it would fail to examine the contents of
  	 * subselects.
  	 */
  	varList = pull_var_clause(expr,
  							  PVC_REJECT_AGGREGATES,
  							  PVC_REJECT_PLACEHOLDERS);
  	keycount = list_length(varList);
  
  	if (keycount > 0)
  	{
  		ListCell   *vl;
  		int			i = 0;
  
  		attNos = (int16 *) palloc(keycount * sizeof(int16));
  		foreach(vl, varList)
  		{
  			Var		   *var = (Var *) lfirst(vl);
  			int			j;
  
  			for (j = 0; j < i; j++)
  				if (attNos[j] == var->varattno)
  					break;
  			if (j == i)
  				attNos[i++] = var->varattno;
  		}
  		keycount = i;
  	}
  	else
  		attNos = NULL;
  
  	/*
  	 * Create the Check Constraint
  	 */
  	CreateConstraintEntry(ccname,		/* Constraint Name */
  						  RelationGetNamespace(rel),	/* namespace */
  						  CONSTRAINT_CHECK,		/* Constraint Type */
  						  false,	/* Is Deferrable */
  						  false,	/* Is Deferred */
  						  RelationGetRelid(rel),		/* relation */
  						  attNos,		/* attrs in the constraint */
  						  keycount,		/* # attrs in the constraint */
  						  InvalidOid,	/* not a domain constraint */
  						  InvalidOid,	/* no associated index */
  						  InvalidOid,	/* Foreign key fields */
  						  NULL,
  						  NULL,
  						  NULL,
  						  NULL,
  						  0,
  						  ' ',
  						  ' ',
  						  ' ',
  						  NULL, /* not an exclusion constraint */
  						  expr, /* Tree form of check constraint */
  						  ccbin,	/* Binary form of check constraint */
  						  ccsrc,	/* Source form of check constraint */
  						  is_local,		/* conislocal */
  						  inhcount);	/* coninhcount */
  
  	pfree(ccbin);
  	pfree(ccsrc);
  }
  
  /*
   * Store defaults and constraints (passed as a list of CookedConstraint).
   *
   * NOTE: only pre-cooked expressions will be passed this way, which is to
   * say expressions inherited from an existing relation.  Newly parsed
   * expressions can be added later, by direct calls to StoreAttrDefault
   * and StoreRelCheck (see AddRelationNewConstraints()).
   */
  static void
  StoreConstraints(Relation rel, List *cooked_constraints)
  {
  	int			numchecks = 0;
  	ListCell   *lc;
  
  	if (!cooked_constraints)
  		return;					/* nothing to do */
  
  	/*
  	 * Deparsing of constraint expressions will fail unless the just-created
  	 * pg_attribute tuples for this relation are made visible.  So, bump the
  	 * command counter.  CAUTION: this will cause a relcache entry rebuild.
  	 */
  	CommandCounterIncrement();
  
  	foreach(lc, cooked_constraints)
  	{
  		CookedConstraint *con = (CookedConstraint *) lfirst(lc);
  
  		switch (con->contype)
  		{
  			case CONSTR_DEFAULT:
  				StoreAttrDefault(rel, con->attnum, con->expr);
  				break;
  			case CONSTR_CHECK:
  				StoreRelCheck(rel, con->name, con->expr,
  							  con->is_local, con->inhcount);
  				numchecks++;
  				break;
  			default:
  				elog(ERROR, "unrecognized constraint type: %d",
  					 (int) con->contype);
  		}
  	}
  
  	if (numchecks > 0)
  		SetRelationNumChecks(rel, numchecks);
  }
  
  /*
   * AddRelationNewConstraints
   *
   * Add new column default expressions and/or constraint check expressions
   * to an existing relation.  This is defined to do both for efficiency in
   * DefineRelation, but of course you can do just one or the other by passing
   * empty lists.
   *
   * rel: relation to be modified
   * newColDefaults: list of RawColumnDefault structures
   * newConstraints: list of Constraint nodes
   * allow_merge: TRUE if check constraints may be merged with existing ones
   * is_local: TRUE if definition is local, FALSE if it's inherited
   *
   * All entries in newColDefaults will be processed.  Entries in newConstraints
   * will be processed only if they are CONSTR_CHECK type.
   *
   * Returns a list of CookedConstraint nodes that shows the cooked form of
   * the default and constraint expressions added to the relation.
   *
   * NB: caller should have opened rel with AccessExclusiveLock, and should
   * hold that lock till end of transaction.	Also, we assume the caller has
   * done a CommandCounterIncrement if necessary to make the relation's catalog
   * tuples visible.
   */
  List *
  AddRelationNewConstraints(Relation rel,
  						  List *newColDefaults,
  						  List *newConstraints,
  						  bool allow_merge,
  						  bool is_local)
  {
  	List	   *cookedConstraints = NIL;
  	TupleDesc	tupleDesc;
  	TupleConstr *oldconstr;
  	int			numoldchecks;
  	ParseState *pstate;
  	RangeTblEntry *rte;
  	int			numchecks;
  	List	   *checknames;
  	ListCell   *cell;
  	Node	   *expr;
  	CookedConstraint *cooked;
  
  	/*
  	 * Get info about existing constraints.
  	 */
  	tupleDesc = RelationGetDescr(rel);
  	oldconstr = tupleDesc->constr;
  	if (oldconstr)
  		numoldchecks = oldconstr->num_check;
  	else
  		numoldchecks = 0;
  
  	/*
  	 * Create a dummy ParseState and insert the target relation as its sole
  	 * rangetable entry.  We need a ParseState for transformExpr.
  	 */
  	pstate = make_parsestate(NULL);
  	rte = addRangeTableEntryForRelation(pstate,
  										rel,
  										NULL,
  										false,
  										true);
  	addRTEtoQuery(pstate, rte, true, true, true);
  
  	/*
  	 * Process column default expressions.
  	 */
  	foreach(cell, newColDefaults)
  	{
  		RawColumnDefault *colDef = (RawColumnDefault *) lfirst(cell);
  		Form_pg_attribute atp = rel->rd_att->attrs[colDef->attnum - 1];
  
  		expr = cookDefault(pstate, colDef->raw_default,
  						   atp->atttypid, atp->atttypmod,
  						   NameStr(atp->attname));
  
  		/*
  		 * If the expression is just a NULL constant, we do not bother to make
  		 * an explicit pg_attrdef entry, since the default behavior is
  		 * equivalent.
  		 *
  		 * Note a nonobvious property of this test: if the column is of a
  		 * domain type, what we'll get is not a bare null Const but a
  		 * CoerceToDomain expr, so we will not discard the default.  This is
  		 * critical because the column default needs to be retained to
  		 * override any default that the domain might have.
  		 */
  		if (expr == NULL ||
  			(IsA(expr, Const) &&((Const *) expr)->constisnull))
  			continue;
  
  		StoreAttrDefault(rel, colDef->attnum, expr);
  
  		cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
  		cooked->contype = CONSTR_DEFAULT;
  		cooked->name = NULL;
  		cooked->attnum = colDef->attnum;
  		cooked->expr = expr;
  		cooked->is_local = is_local;
  		cooked->inhcount = is_local ? 0 : 1;
  		cookedConstraints = lappend(cookedConstraints, cooked);
  	}
  
  	/*
  	 * Process constraint expressions.
  	 */
  	numchecks = numoldchecks;
  	checknames = NIL;
  	foreach(cell, newConstraints)
  	{
  		Constraint *cdef = (Constraint *) lfirst(cell);
  		char	   *ccname;
  
  		if (cdef->contype != CONSTR_CHECK)
  			continue;
  
  		if (cdef->raw_expr != NULL)
  		{
  			Assert(cdef->cooked_expr == NULL);
  
  			/*
  			 * Transform raw parsetree to executable expression, and verify
  			 * it's valid as a CHECK constraint.
  			 */
  			expr = cookConstraint(pstate, cdef->raw_expr,
  								  RelationGetRelationName(rel));
  		}
  		else
  		{
  			Assert(cdef->cooked_expr != NULL);
  
  			/*
  			 * Here, we assume the parser will only pass us valid CHECK
  			 * expressions, so we do no particular checking.
  			 */
  			expr = stringToNode(cdef->cooked_expr);
  		}
  
  		/*
  		 * Check name uniqueness, or generate a name if none was given.
  		 */
  		if (cdef->conname != NULL)
  		{
  			ListCell   *cell2;
  
  			ccname = cdef->conname;
  			/* Check against other new constraints */
  			/* Needed because we don't do CommandCounterIncrement in loop */
  			foreach(cell2, checknames)
  			{
  				if (strcmp((char *) lfirst(cell2), ccname) == 0)
  					ereport(ERROR,
  							(errcode(ERRCODE_DUPLICATE_OBJECT),
  							 errmsg("check constraint \"%s\" already exists",
  									ccname)));
  			}
  
  			/* save name for future checks */
  			checknames = lappend(checknames, ccname);
  
  			/*
  			 * Check against pre-existing constraints.	If we are allowed to
  			 * merge with an existing constraint, there's no more to do here.
  			 * (We omit the duplicate constraint from the result, which is
  			 * what ATAddCheckConstraint wants.)
  			 */
  			if (MergeWithExistingConstraint(rel, ccname, expr,
  											allow_merge, is_local))
  				continue;
  		}
  		else
  		{
  			/*
  			 * When generating a name, we want to create "tab_col_check" for a
  			 * column constraint and "tab_check" for a table constraint.  We
  			 * no longer have any info about the syntactic positioning of the
  			 * constraint phrase, so we approximate this by seeing whether the
  			 * expression references more than one column.	(If the user
  			 * played by the rules, the result is the same...)
  			 *
  			 * Note: pull_var_clause() doesn't descend into sublinks, but we
  			 * eliminated those above; and anyway this only needs to be an
  			 * approximate answer.
  			 */
  			List	   *vars;
  			char	   *colname;
  
  			vars = pull_var_clause(expr,
  								   PVC_REJECT_AGGREGATES,
  								   PVC_REJECT_PLACEHOLDERS);
  
  			/* eliminate duplicates */
  			vars = list_union(NIL, vars);
  
  			if (list_length(vars) == 1)
  				colname = get_attname(RelationGetRelid(rel),
  									  ((Var *) linitial(vars))->varattno);
  			else
  				colname = NULL;
  
  			ccname = ChooseConstraintName(RelationGetRelationName(rel),
  										  colname,
  										  "check",
  										  RelationGetNamespace(rel),
  										  checknames);
  
  			/* save name for future checks */
  			checknames = lappend(checknames, ccname);
  		}
  
  		/*
  		 * OK, store it.
  		 */
  		StoreRelCheck(rel, ccname, expr, is_local, is_local ? 0 : 1);
  
  		numchecks++;
  
  		cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
  		cooked->contype = CONSTR_CHECK;
  		cooked->name = ccname;
  		cooked->attnum = 0;
  		cooked->expr = expr;
  		cooked->is_local = is_local;
  		cooked->inhcount = is_local ? 0 : 1;
  		cookedConstraints = lappend(cookedConstraints, cooked);
  	}
  
  	/* Cleanup the parse state */
  	free_parsestate(pstate);
  
  	/*
  	 * Update the count of constraints in the relation's pg_class tuple. We do
  	 * this even if there was no change, in order to ensure that an SI update
  	 * message is sent out for the pg_class tuple, which will force other
  	 * backends to rebuild their relcache entries for the rel. (This is
  	 * critical if we added defaults but not constraints.)
  	 */
  	SetRelationNumChecks(rel, numchecks);
  
  	return cookedConstraints;
  }
  
  /*
   * Check for a pre-existing check constraint that conflicts with a proposed
   * new one, and either adjust its conislocal/coninhcount settings or throw
   * error as needed.
   *
   * Returns TRUE if merged (constraint is a duplicate), or FALSE if it's
   * got a so-far-unique name, or throws error if conflict.
   */
  static bool
  MergeWithExistingConstraint(Relation rel, char *ccname, Node *expr,
  							bool allow_merge, bool is_local)
  {
  	bool		found;
  	Relation	conDesc;
  	SysScanDesc conscan;
  	ScanKeyData skey[2];
  	HeapTuple	tup;
  
  	/* Search for a pg_constraint entry with same name and relation */
  	conDesc = heap_open(ConstraintRelationId, RowExclusiveLock);
  
  	found = false;
  
  	ScanKeyInit(&skey[0],
  				Anum_pg_constraint_conname,
  				BTEqualStrategyNumber, F_NAMEEQ,
  				CStringGetDatum(ccname));
  
  	ScanKeyInit(&skey[1],
  				Anum_pg_constraint_connamespace,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(RelationGetNamespace(rel)));
  
  	conscan = systable_beginscan(conDesc, ConstraintNameNspIndexId, true,
  								 SnapshotNow, 2, skey);
  
  	while (HeapTupleIsValid(tup = systable_getnext(conscan)))
  	{
  		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tup);
  
  		if (con->conrelid == RelationGetRelid(rel))
  		{
  			/* Found it.  Conflicts if not identical check constraint */
  			if (con->contype == CONSTRAINT_CHECK)
  			{
  				Datum		val;
  				bool		isnull;
  
  				val = fastgetattr(tup,
  								  Anum_pg_constraint_conbin,
  								  conDesc->rd_att, &isnull);
  				if (isnull)
  					elog(ERROR, "null conbin for rel %s",
  						 RelationGetRelationName(rel));
  				if (equal(expr, stringToNode(TextDatumGetCString(val))))
  					found = true;
  			}
  			if (!found || !allow_merge)
  				ereport(ERROR,
  						(errcode(ERRCODE_DUPLICATE_OBJECT),
  				errmsg("constraint \"%s\" for relation \"%s\" already exists",
  					   ccname, RelationGetRelationName(rel))));
  			/* OK to update the tuple */
  			ereport(NOTICE,
  			   (errmsg("merging constraint \"%s\" with inherited definition",
  					   ccname)));
  			tup = heap_copytuple(tup);
  			con = (Form_pg_constraint) GETSTRUCT(tup);
  			if (is_local)
  				con->conislocal = true;
  			else
  				con->coninhcount++;
  			simple_heap_update(conDesc, &tup->t_self, tup);
  			CatalogUpdateIndexes(conDesc, tup);
  			break;
  		}
  	}
  
  	systable_endscan(conscan);
  	heap_close(conDesc, RowExclusiveLock);
  
  	return found;
  }
  
  /*
   * Update the count of constraints in the relation's pg_class tuple.
   *
   * Caller had better hold exclusive lock on the relation.
   *
   * An important side effect is that a SI update message will be sent out for
   * the pg_class tuple, which will force other backends to rebuild their
   * relcache entries for the rel.  Also, this backend will rebuild its
   * own relcache entry at the next CommandCounterIncrement.
   */
  void
  SetRelationNumChecks(Relation rel, int numchecks)
  {
  	Relation	relrel;
  	HeapTuple	reltup;
  	Form_pg_class relStruct;
  
  	relrel = heap_open(RelationRelationId, RowExclusiveLock);
  	reltup = SearchSysCacheCopy1(RELOID,
  								 ObjectIdGetDatum(RelationGetRelid(rel)));
  	if (!HeapTupleIsValid(reltup))
  		elog(ERROR, "cache lookup failed for relation %u",
  			 RelationGetRelid(rel));
  	relStruct = (Form_pg_class) GETSTRUCT(reltup);
  
  	if (relStruct->relchecks != numchecks)
  	{
  		relStruct->relchecks = numchecks;
  
  		simple_heap_update(relrel, &reltup->t_self, reltup);
  
  		/* keep catalog indexes current */
  		CatalogUpdateIndexes(relrel, reltup);
  	}
  	else
  	{
  		/* Skip the disk update, but force relcache inval anyway */
  		CacheInvalidateRelcache(rel);
  	}
  
  	heap_freetuple(reltup);
  	heap_close(relrel, RowExclusiveLock);
  }
  
  /*
   * Take a raw default and convert it to a cooked format ready for
   * storage.
   *
   * Parse state should be set up to recognize any vars that might appear
   * in the expression.  (Even though we plan to reject vars, it's more
   * user-friendly to give the correct error message than "unknown var".)
   *
   * If atttypid is not InvalidOid, coerce the expression to the specified
   * type (and typmod atttypmod).   attname is only needed in this case:
   * it is used in the error message, if any.
   */
  Node *
  cookDefault(ParseState *pstate,
  			Node *raw_default,
  			Oid atttypid,
  			int32 atttypmod,
  			char *attname)
  {
  	Node	   *expr;
  
  	Assert(raw_default != NULL);
  
  	/*
  	 * Transform raw parsetree to executable expression.
  	 */
  	expr = transformExpr(pstate, raw_default, EXPR_KIND_COLUMN_DEFAULT);
  
  	/*
  	 * Make sure default expr does not refer to any vars (we need this check
  	 * since the pstate includes the target table).
  	 */
  	if (contain_var_clause(expr))
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  			  errmsg("cannot use column references in default expression")));
  
  	/*
  	 * transformExpr() should have already rejected subqueries, aggregates,
  	 * and window functions, based on the EXPR_KIND_ for a default expression.
  	 *
  	 * It can't return a set either.
  	 */
  	if (expression_returns_set(expr))
  		ereport(ERROR,
  				(errcode(ERRCODE_DATATYPE_MISMATCH),
  				 errmsg("default expression must not return a set")));
  
  	/*
  	 * Coerce the expression to the correct type and typmod, if given. This
  	 * should match the parser's processing of non-defaulted expressions ---
  	 * see transformAssignedExpr().
  	 */
  	if (OidIsValid(atttypid))
  	{
  		Oid			type_id = exprType(expr);
  
  		expr = coerce_to_target_type(pstate, expr, type_id,
  									 atttypid, atttypmod,
  									 COERCION_ASSIGNMENT,
  									 COERCE_IMPLICIT_CAST,
  									 -1);
  		if (expr == NULL)
  			ereport(ERROR,
  					(errcode(ERRCODE_DATATYPE_MISMATCH),
  					 errmsg("column \"%s\" is of type %s"
  							" but default expression is of type %s",
  							attname,
  							format_type_be(atttypid),
  							format_type_be(type_id)),
  			   errhint("You will need to rewrite or cast the expression.")));
  	}
  
  	return expr;
  }
  
  /*
   * Take a raw CHECK constraint expression and convert it to a cooked format
   * ready for storage.
   *
   * Parse state must be set up to recognize any vars that might appear
   * in the expression.
   */
  static Node *
  cookConstraint(ParseState *pstate,
  			   Node *raw_constraint,
  			   char *relname)
  {
  	Node	   *expr;
  
  	/*
  	 * Transform raw parsetree to executable expression.
  	 */
  	expr = transformExpr(pstate, raw_constraint, EXPR_KIND_CHECK_CONSTRAINT);
  
  	/*
  	 * Make sure it yields a boolean result.
  	 */
  	expr = coerce_to_boolean(pstate, expr, "CHECK");
  
  	/*
  	 * Make sure no outside relations are referred to.
  	 */
  	if (list_length(pstate->p_rtable) != 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  			errmsg("only table \"%s\" can be referenced in check constraint",
  				   relname)));
  
  	return expr;
  }
  
  
  /*
   * RemoveStatistics --- remove entries in pg_statistic for a rel or column
   *
   * If attnum is zero, remove all entries for rel; else remove only the one(s)
   * for that column.
   */
  void
  RemoveStatistics(Oid relid, AttrNumber attnum)
  {
  	Relation	pgstatistic;
  	SysScanDesc scan;
  	ScanKeyData key[2];
  	int			nkeys;
  	HeapTuple	tuple;
  
  	pgstatistic = heap_open(StatisticRelationId, RowExclusiveLock);
  
  	ScanKeyInit(&key[0],
  				Anum_pg_statistic_starelid,
  				BTEqualStrategyNumber, F_OIDEQ,
  				ObjectIdGetDatum(relid));
  
  	if (attnum == 0)
  		nkeys = 1;
  	else
  	{
  		ScanKeyInit(&key[1],
  					Anum_pg_statistic_staattnum,
  					BTEqualStrategyNumber, F_INT2EQ,
  					Int16GetDatum(attnum));
  		nkeys = 2;
  	}
  
  	scan = systable_beginscan(pgstatistic, StatisticRelidAttnumInhIndexId, true,
  							  SnapshotNow, nkeys, key);
  
  	/* we must loop even when attnum != 0, in case of inherited stats */
  	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
  		simple_heap_delete(pgstatistic, &tuple->t_self);
  
  	systable_endscan(scan);
  
  	heap_close(pgstatistic, RowExclusiveLock);
  }
  
  
  /*
   * RelationTruncateIndexes - truncate all indexes associated
   * with the heap relation to zero tuples.
   *
   * The routine will truncate and then reconstruct the indexes on
   * the specified relation.	Caller must hold exclusive lock on rel.
   */
  static void
  RelationTruncateIndexes(Relation heapRelation)
  {
  	ListCell   *indlist;
  
  	/* Ask the relcache to produce a list of the indexes of the rel */
  	foreach(indlist, RelationGetIndexList(heapRelation))
  	{
  		Oid			indexId = lfirst_oid(indlist);
  		Relation	currentIndex;
  		IndexInfo  *indexInfo;
  
  		/* Open the index relation; use exclusive lock, just to be sure */
  		currentIndex = index_open(indexId, AccessExclusiveLock);
  
  		/* Fetch info needed for index_build */
  		indexInfo = BuildIndexInfo(currentIndex);
  
  		/* Now truncate the actual file (and discard buffers) */
  		RelationTruncate(currentIndex, 0);
  
  		/* Initialize the index and rebuild */
  		/* Note: we do not need to re-establish pkey setting */
  		index_build(heapRelation, currentIndex, indexInfo, false, true);
  
  		/* We're done with this index */
  		index_close(currentIndex, NoLock);
  	}
  }
  
  /*
   *	 heap_truncate
   *
   *	 This routine deletes all data within all the specified relations.
   *
   * This is not transaction-safe!  There is another, transaction-safe
   * implementation in commands/tablecmds.c.	We now use this only for
   * ON COMMIT truncation of temporary tables, where it doesn't matter.
   */
  void
  heap_truncate(List *relids)
  {
  	List	   *relations = NIL;
  	ListCell   *cell;
  
  	/* Open relations for processing, and grab exclusive access on each */
  	foreach(cell, relids)
  	{
  		Oid			rid = lfirst_oid(cell);
  		Relation	rel;
  
  		rel = heap_open(rid, AccessExclusiveLock);
  		relations = lappend(relations, rel);
  	}
  
  	/* Don't allow truncate on tables that are referenced by foreign keys */
  	heap_truncate_check_FKs(relations, true);
  
  	/* OK to do it */
  	foreach(cell, relations)
  	{
  		Relation	rel = lfirst(cell);
  
  		/*
  		 * Truncating AO and auxiliary tables' relfiles, like in case
  		 * of heap tables, leaves the AO table in an inconsistent
  		 * state at the end of commit:
  		 *
  		 *    - The aoseg table indicates no segfiles on disk.
  		 *    - AO segment files are truncated, with EOF = 0.
  		 *    - The EOF recorded in persistent tables for the AO
  		 *      segment files, however, is greater than 0 if the
  		 *      transaction inserted tuples in the AO table.
  		 *
  		 * One may think of resetting the EOF in persistent tables to
  		 * 0.  Beware, EOF of AO segfiles can only increase.  Filerep
  		 * incremental recovery relies on this assumption.
  		 *
  		 * Therefore, ON COMMIT DELETE ROWS action for AO tables is
  		 * implemented by creating new segment file and scheduling
  		 * existing one for drop at the end of commit.  TRUNCATE TABLE
  		 * command works the same way.  At some point, all temporary
  		 * tables should be exempt from persistent tables/lifecycle
  		 * management.
  		 */
  
  		if (RelationIsAoRows(rel) || RelationIsAoCols(rel))
  		{
  			/*
  			 * GPDB_90_MERGE_FIXME: see commit cab9a0656, which changed how
  			 * truncation was done for heap tables. Do we need a matching change
  			 * here, and does the removal of filerep change any of the
  			 * assumptions in the above comment?
  			 */
  			TruncateRelfiles(rel, InvalidSubTransactionId);
  			reindex_relation(RelationGetRelid(rel), true, true);
  		}
  		else
  		{
  			/* Truncate the relation */
  			heap_truncate_one_rel(rel);
  		}
  
  		/* Close the relation, but keep exclusive lock on it until commit */
  		heap_close(rel, NoLock);
  	}
  }
  
  /*
   *	 heap_truncate_one_rel
   *
   *	 This routine deletes all data within the specified relation.
   *
   * This is not transaction-safe, because the truncation is done immediately
   * and cannot be rolled back later.  Caller is responsible for having
   * checked permissions etc, and must have obtained AccessExclusiveLock.
   */
  void
  heap_truncate_one_rel(Relation rel)
  {
  	Oid			toastrelid;
  
  	/* Truncate the actual file (and discard buffers) */
  	RelationTruncate(rel, 0);
  
  	/* If the relation has indexes, truncate the indexes too */
  	RelationTruncateIndexes(rel);
  
  	/* If there is a toast table, truncate that too */
  	toastrelid = rel->rd_rel->reltoastrelid;
  	if (OidIsValid(toastrelid))
  	{
  		Relation	toastrel = heap_open(toastrelid, AccessExclusiveLock);
  
  		RelationTruncate(toastrel, 0);
  		RelationTruncateIndexes(toastrel);
  		/* keep the lock... */
  		heap_close(toastrel, NoLock);
  	}
  }
  
  /*
   * heap_truncate_check_FKs
   *		Check for foreign keys referencing a list of relations that
   *		are to be truncated, and raise error if there are any
   *
   * We disallow such FKs (except self-referential ones) since the whole point
   * of TRUNCATE is to not scan the individual rows to be thrown away.
   *
   * This is split out so it can be shared by both implementations of truncate.
   * Caller should already hold a suitable lock on the relations.
   *
   * tempTables is only used to select an appropriate error message.
   */
  void
  heap_truncate_check_FKs(List *relations, bool tempTables)
  {
  	List	   *oids = NIL;
  	List	   *dependents;
  	ListCell   *cell;
  
  	/*
  	 * Build a list of OIDs of the interesting relations.
  	 *
  	 * If a relation has no triggers, then it can neither have FKs nor be
  	 * referenced by a FK from another table, so we can ignore it.
  	 */
  	foreach(cell, relations)
  	{
  		Relation	rel = lfirst(cell);
  
  		if (rel->rd_rel->relhastriggers)
  			oids = lappend_oid(oids, RelationGetRelid(rel));
  	}
  
  	/*
  	 * Fast path: if no relation has triggers, none has FKs either.
  	 */
  	if (oids == NIL)
  		return;
  
  	/*
  	 * Otherwise, must scan pg_constraint.	We make one pass with all the
  	 * relations considered; if this finds nothing, then all is well.
  	 */
  	dependents = heap_truncate_find_FKs(oids);
  	if (dependents == NIL)
  		return;
  
  	/*
  	 * Otherwise we repeat the scan once per relation to identify a particular
  	 * pair of relations to complain about.  This is pretty slow, but
  	 * performance shouldn't matter much in a failure path.  The reason for
  	 * doing things this way is to ensure that the message produced is not
  	 * dependent on chance row locations within pg_constraint.
  	 */
  	foreach(cell, oids)
  	{
  		Oid			relid = lfirst_oid(cell);
  		ListCell   *cell2;
  
  		dependents = heap_truncate_find_FKs(list_make1_oid(relid));
  
  		foreach(cell2, dependents)
  		{
  			Oid			relid2 = lfirst_oid(cell2);
  
  			if (!list_member_oid(oids, relid2))
  			{
  				char	   *relname = get_rel_name(relid);
  				char	   *relname2 = get_rel_name(relid2);
  
  				if (tempTables)
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("unsupported ON COMMIT and foreign key combination"),
  							 errdetail("Table \"%s\" references \"%s\", but they do not have the same ON COMMIT setting.",
  									   relname2, relname)));
  				else
  					ereport(ERROR,
  							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  							 errmsg("cannot truncate a table referenced in a foreign key constraint"),
  							 errdetail("Table \"%s\" references \"%s\".",
  									   relname2, relname),
  						   errhint("Truncate table \"%s\" at the same time, "
  								   "or use TRUNCATE ... CASCADE.",
  								   relname2)));
  			}
  		}
  	}
  }
  
  /*
   * heap_truncate_find_FKs
   *		Find relations having foreign keys referencing any of the given rels
   *
   * Input and result are both lists of relation OIDs.  The result contains
   * no duplicates, does *not* include any rels that were already in the input
   * list, and is sorted in OID order.  (The last property is enforced mainly
   * to guarantee consistent behavior in the regression tests; we don't want
   * behavior to change depending on chance locations of rows in pg_constraint.)
   *
   * Note: caller should already have appropriate lock on all rels mentioned
   * in relationIds.	Since adding or dropping an FK requires exclusive lock
   * on both rels, this ensures that the answer will be stable.
   */
  List *
  heap_truncate_find_FKs(List *relationIds)
  {
  	List	   *result = NIL;
  	Relation	fkeyRel;
  	SysScanDesc fkeyScan;
  	HeapTuple	tuple;
  
  	/*
  	 * Must scan pg_constraint.  Right now, it is a seqscan because there is
  	 * no available index on confrelid.
  	 */
  	fkeyRel = heap_open(ConstraintRelationId, AccessShareLock);
  
  	fkeyScan = systable_beginscan(fkeyRel, InvalidOid, false,
  								  SnapshotNow, 0, NULL);
  
  	while (HeapTupleIsValid(tuple = systable_getnext(fkeyScan)))
  	{
  		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
  
  		/* Not a foreign key */
  		if (con->contype != CONSTRAINT_FOREIGN)
  			continue;
  
  		/* Not referencing one of our list of tables */
  		if (!list_member_oid(relationIds, con->confrelid))
  			continue;
  
  		/* Add referencer unless already in input or result list */
  		if (!list_member_oid(relationIds, con->conrelid))
  			result = insert_ordered_unique_oid(result, con->conrelid);
  	}
  
  	systable_endscan(fkeyScan);
  	heap_close(fkeyRel, AccessShareLock);
  
  	return result;
  }
  
  /*
   * insert_ordered_unique_oid
   *		Insert a new Oid into a sorted list of Oids, preserving ordering,
   *		and eliminating duplicates
   *
   * Building the ordered list this way is O(N^2), but with a pretty small
   * constant, so for the number of entries we expect it will probably be
   * faster than trying to apply qsort().  It seems unlikely someone would be
   * trying to truncate a table with thousands of dependent tables ...
   */
  static List *
  insert_ordered_unique_oid(List *list, Oid datum)
  {
  	ListCell   *prev;
  
  	/* Does the datum belong at the front? */
  	if (list == NIL || datum < linitial_oid(list))
  		return lcons_oid(datum, list);
  	/* Does it match the first entry? */
  	if (datum == linitial_oid(list))
  		return list;			/* duplicate, so don't insert */
  	/* No, so find the entry it belongs after */
  	prev = list_head(list);
  	for (;;)
  	{
  		ListCell   *curr = lnext(prev);
  
  		if (curr == NULL || datum < lfirst_oid(curr))
  			break;				/* it belongs after 'prev', before 'curr' */
  
  		if (datum == lfirst_oid(curr))
  			return list;		/* duplicate, so don't insert */
  
  		prev = curr;
  	}
  	/* Insert datum into list after 'prev' */
  	lappend_cell_oid(list, prev, datum);
  	return list;
  }
  
  bool
  should_have_valid_relfrozenxid(char relkind, char relstorage)
  {
  	switch (relkind)
  	{
  		case RELKIND_RELATION:
  			if (relstorage == RELSTORAGE_EXTERNAL ||
  				relstorage == RELSTORAGE_FOREIGN  ||
  				relstorage == RELSTORAGE_VIRTUAL ||
  				relstorage == RELSTORAGE_AOROWS ||
  				relstorage == RELSTORAGE_AOCOLS)
  			{
  				return false;
  			}
  			return true;
  
  		case RELKIND_TOASTVALUE:
  		case RELKIND_AOSEGMENTS:
  		case RELKIND_AOBLOCKDIR:
  		case RELKIND_AOVISIMAP:
  			return true;
  	}
  
  	return false;
  }
  