text: /*-------------------------------------------------------------------------
   *
   * namespace.c
   *	  code to support accessing and searching namespaces
   *
   * This is separate from pg_namespace.c, which contains the routines that
   * directly manipulate the pg_namespace system catalog.  This module
   * provides routines associated with defining a "namespace search path"
   * and implementing search-path-controlled searches.
   *
   *
   * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * IDENTIFICATION
   *	  $PostgreSQL: pgsql/src/backend/catalog/namespace.c,v 1.88.2.1 2007/04/20 02:37:48 tgl Exp $
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/genam.h"
  #include "access/xact.h"
  #include "access/hd_work_mgr.h"
  #include "catalog/catquery.h"
  #include "catalog/dependency.h"
  #include "catalog/indexing.h"
  #include "catalog/namespace.h"
  #include "catalog/pg_authid.h"
  #include "catalog/pg_conversion.h"
  #include "catalog/pg_database.h"
  #include "catalog/pg_namespace.h"
  #include "catalog/pg_opclass.h"
  #include "catalog/pg_operator.h"
  #include "catalog/pg_proc.h"
  #include "catalog/pg_type.h"
  #include "commands/dbcommands.h"
  #include "commands/schemacmds.h"
  #include "miscadmin.h"
  #include "nodes/makefuncs.h"
  #include "storage/backendid.h"
  #include "storage/ipc.h"
  #include "utils/acl.h"
  #include "utils/builtins.h"
  #include "utils/fmgroids.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/syscache.h"
  #include "utils/guc.h"
  #include "utils/hsearch.h"
  #include "cdb/cdbvars.h"
  #include "tcop/utility.h"
  
  
  /*
   * The namespace search path is a possibly-empty list of namespace OIDs.
   * In addition to the explicit list, several implicitly-searched namespaces
   * may be included:
   *
   * 1. If a "special" namespace has been set by PushSpecialNamespace, it is
   * always searched first.  (This is a hack for CREATE SCHEMA.)
   *
   * 2. If a TEMP table namespace has been initialized in this session, it
   * is always searched just after any special namespace.
   *
   * 3. The system catalog namespace is always searched.	If the system
   * namespace is present in the explicit path then it will be searched in
   * the specified order; otherwise it will be searched after TEMP tables and
   * *before* the explicit list.	(It might seem that the system namespace
   * should be implicitly last, but this behavior appears to be required by
   * SQL99.  Also, this provides a way to search the system namespace first
   * without thereby making it the default creation target namespace.)
   *
   * For security reasons, searches using the search path will ignore the temp
   * namespace when searching for any object type other than relations and
   * types.  (We must allow types since temp tables have rowtypes.)
   *
   * The default creation target namespace is normally equal to the first
   * element of the explicit list, but is the "special" namespace when one
   * has been set.  If the explicit list is empty and there is no special
   * namespace, there is no default target.
   *
   * The textual specification of search_path can include "$user" to refer to
   * the namespace named the same as the current user, if any.  (This is just
   * ignored if there is no such namespace.)  Also, it can include "pg_temp"
   * to refer to the current backend's temp namespace.  This is usually also
   * ignorable if the temp namespace hasn't been set up, but there's a special
   * case: if "pg_temp" appears first then it should be the default creation
   * target.  We kluge this case a little bit so that the temp namespace isn't
   * set up until the first attempt to create something in it.  (The reason for
   * klugery is that we can't create the temp namespace outside a transaction,
   * but initial GUC processing of search_path happens outside a transaction.)
   * tempCreationPending is TRUE if "pg_temp" appears first in the string but
   * is not reflected in defaultCreationNamespace because the namespace isn't
   * set up yet.
   *
   * In bootstrap mode, the search path is set equal to "pg_catalog", so that
   * the system namespace is the only one searched or inserted into.
   * The initdb script is also careful to set search_path to "pg_catalog" for
   * its post-bootstrap standalone backend runs.	Otherwise the default search
   * path is determined by GUC.  The factory default path contains the PUBLIC
   * namespace (if it exists), preceded by the user's personal namespace
   * (if one exists).
   *
   * If namespaceSearchPathValid is false, then namespaceSearchPath (and other
   * derived variables) need to be recomputed from namespace_search_path.
   * We mark it invalid upon an assignment to namespace_search_path or receipt
   * of a syscache invalidation event for pg_namespace.  The recomputation
   * is done during the next lookup attempt.
   *
   * Any namespaces mentioned in namespace_search_path that are not readable
   * by the current user ID are simply left out of namespaceSearchPath; so
   * we have to be willing to recompute the path when current userid changes.
   * namespaceUser is the userid the path has been computed for.
   */
  
  extern const char *debug_query_string;
  
  static List *namespaceSearchPath = NIL;
  
  static Oid	namespaceUser = InvalidOid;
  
  /* default place to create stuff; if InvalidOid, no default */
  static Oid	defaultCreationNamespace = InvalidOid;
  
  /* first explicit member of list; usually same as defaultCreationNamespace */
  static Oid	firstExplicitNamespace = InvalidOid;
  
  /* if TRUE, defaultCreationNamespace is wrong, it should be temp namespace */
  static bool tempCreationPending = false;
  
  /* The above five values are valid only if namespaceSearchPathValid */
  static bool namespaceSearchPathValid = true;
  
  /* store the query sign on the last call of recomputeNamespacePath(), and used the sign to judge cache invalidation */
  static uint32 last_query_sign = 0;
  
  /*
   * myTempNamespace is InvalidOid until and unless a TEMP namespace is set up
   * in a particular backend session (this happens when a CREATE TEMP TABLE
   * command is first executed).	Thereafter it's the OID of the temp namespace.
   *
   * myTempNamespaceSubID shows whether we've created the TEMP namespace in the
   * current subtransaction.	The flag propagates up the subtransaction tree,
   * so the main transaction will correctly recognize the flag if all
   * intermediate subtransactions commit.  When it is InvalidSubTransactionId,
   * we either haven't made the TEMP namespace yet, or have successfully
   * committed its creation, depending on whether myTempNamespace is valid.
   */
  static Oid	myTempNamespace = InvalidOid;
  
  static SubTransactionId myTempNamespaceSubID = InvalidSubTransactionId;
  
  /*
   * "Special" namespace for CREATE SCHEMA.  If set, it's the first search
   * path element, and also the default creation namespace.
   */
  static Oid	mySpecialNamespace = InvalidOid;
  
  /*
   * This is the text equivalent of the search path --- it's the value
   * of the GUC variable 'search_path'.
   */
  char	   *namespace_search_path = NULL;
  
  
  /* Local functions */
  static void recomputeNamespacePath(void);
  static void checkNamespaceInternal(List **oidlist, Oid namespaceId, Oid roleid);
  static void InitTempTableNamespace(void);
  static void RemoveTempRelations(Oid tempNamespaceId);
  static void RemoveTempRelationsCallback(int code, Datum arg);
  static void NamespaceCallback(Datum arg __attribute__((unused)) , Oid relid __attribute__((unused)) );
  static bool TempNamespaceValid(bool error_if_removed);
  static bool RelationExists(const RangeVar *relation, Oid dboid);
  
  /* These don't really need to appear in any header file */
  Datum		pg_table_is_visible(PG_FUNCTION_ARGS);
  Datum		pg_type_is_visible(PG_FUNCTION_ARGS);
  Datum		pg_function_is_visible(PG_FUNCTION_ARGS);
  Datum		pg_operator_is_visible(PG_FUNCTION_ARGS);
  Datum		pg_opclass_is_visible(PG_FUNCTION_ARGS);
  Datum		pg_conversion_is_visible(PG_FUNCTION_ARGS);
  Datum		pg_my_temp_schema(PG_FUNCTION_ARGS);
  Datum		pg_is_other_temp_schema(PG_FUNCTION_ARGS);
  Datum       pg_objname_to_oid(PG_FUNCTION_ARGS);
  
  void
  reset_query_sign()
  {
  	last_query_sign = 0;
  }
  
  /*
   * GetCatalogId
   *	Given a catalogname, return 0 if the current database is specified, or the oid from pg_database, if hcatalog is specified. 
   *	Error out if a catalog name is different from the current one or hcatalog
   */
  Oid
  GetCatalogId(const char *catalogname)
  {
  	if (NULL == catalogname || 0 == strcmp(catalogname, get_database_name(MyDatabaseId))) 
  	{
  		return NSPDBOID_CURRENT;
  	}
  
  	if (0 == strcmp(catalogname, "hcatalog"))
  	{
  		return HcatalogDbOid;
  	}	
  
  	ereport(ERROR,	(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cross-database references are not implemented: \"%s\"",
  							catalogname)));
  	return 0;
  }
  
  /*
   * RelationExists
   *		Given a RangeVar describing an existing relation,
   *		check if the relation exists in the pg_namespace and pg_class tables
   *
   */
  bool RelationExists(const RangeVar *relation, Oid dboid)
  {
  	Assert(relation != NULL);
  	Oid namespaceId = LookupExplicitNamespace(relation->schemaname, dboid);
  	Oid relId = get_relname_relid(relation->relname, namespaceId);
  	return OidIsValid(namespaceId) && OidIsValid(relId);
  }
  
  /*
   * RangeVarGetRelid
   *		Given a RangeVar describing an existing relation,
   *		select the proper namespace and look up the relation OID.
   *
   * If the relation is not found, return InvalidOid if failOK = true,
   * otherwise raise an error.
   */
  Oid
  RangeVarGetRelid(const RangeVar *relation, bool failOK, bool allowHcatalog)
  {
  	Oid			namespaceId;
  	Oid			relId;
  
  	/* check if database name is specified: the only allowed options are the current
  	 * database name and the external "hcatalog" specifier
  	 */
  	Oid dboid = GetCatalogId(relation->catalogname);
  	if (HcatalogDbOid == dboid)
  	{
  		if (!allowHcatalog)
  		{
  			ereport(ERROR,
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("reference to hcatalog table \"%s.%s.%s\" is not allowed in this context",
  						relation->catalogname, relation->schemaname,
  						relation->relname)));
  		}
  
  		/* Pull relation metadata via the hcat proxy(pxf) only if relation doesn't exist*/
  		if(!RelationExists(relation, dboid))
  		{
  			StringInfoData location;
  			initStringInfo(&location);
  
  			appendStringInfo(&location, "%s.%s", relation->schemaname, relation->relname);
  
  			// TODO: May 29, 2015 - shivram: revisit returning the hcat tables here
  			List *hcat_tables = get_pxf_item_metadata(HiveProfileName, location.data, HcatalogDbOid);
  			Assert(hcat_tables != NIL);
  			elog(DEBUG2, "Retrieved %d tables from HCatalog for \"%s.%s\"", 
  				list_length(hcat_tables), relation->schemaname, relation->relname);
  			pfree(location.data);
  		}
  	}
  	
  	if (relation->schemaname)
  	{
  		/* use exact schema given */
  		namespaceId = LookupExplicitNamespace(relation->schemaname, dboid);
  		relId = get_relname_relid(relation->relname, namespaceId);
  	}
  	else
  	{
  		/* external references must be fully specified */
  		Assert(NSPDBOID_CURRENT == dboid);
  		
  		/* search the namespace path */
  		relId = RelnameGetRelid(relation->relname);
  	}
  
  	if (!OidIsValid(relId) && !failOK)
  	{
  		if (relation->schemaname)
  		{
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_TABLE),
  					 errmsg("relation \"%s.%s\" does not exist",
  							relation->schemaname, relation->relname),
  					 errOmitLocation(true)));
  		}
  		else
  		{
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_TABLE),
  					 errmsg("relation \"%s\" does not exist",
  							relation->relname),
  					 errOmitLocation(true)));
  		}
  	}
  	return relId;
  }
  
  /*
   * RangeVarGetCreationNamespace
   *		Given a RangeVar describing a to-be-created relation,
   *		choose which namespace to create it in.
   *
   * Note: calling this may result in a CommandCounterIncrement operation.
   * That will happen on the first request for a temp table in any particular
   * backend run; we will need to either create or clean out the temp schema.
   */
  Oid
  RangeVarGetCreationNamespace(const RangeVar *newRelation)
  {
  	Oid			namespaceId;
  
  	/*
  	 * We check the catalog name and then ignore it.
  	 */
  	if (NULL != newRelation->catalogname)
  	{
  		if (strcmp(newRelation->catalogname, "hcatalog") == 0)
  		{
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("creating hcatalog tables is not supported: \"%s.%s.%s\"",
  							newRelation->catalogname, newRelation->schemaname,
  							newRelation->relname)));
  		}
  		
  		if (strcmp(newRelation->catalogname, get_database_name(MyDatabaseId)) != 0)
  		{
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("cross-database references are not implemented: \"%s.%s.%s\"",
  							newRelation->catalogname, newRelation->schemaname,
  							newRelation->relname)));
  		}
  	}
  
  	if (newRelation->istemp)
  	{
  		/* TEMP tables are created in our backend-local temp namespace */
  		if (Gp_role != GP_ROLE_EXECUTE && newRelation->schemaname)
  		{
  			char		namespaceName[NAMEDATALEN];
  			snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d", gp_session_id);
  			if (strcmp(newRelation->schemaname,namespaceName)!=0)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  					  errmsg("temporary tables may not specify a schema name"),
  							   errOmitLocation(true)));
  		}
  		/* Initialize temp namespace if first time through */
  		if (!TempNamespaceValid(false))
  			InitTempTableNamespace();
  		return myTempNamespace;
  	}
  
  	if (newRelation->schemaname)
  	{
  		/* check for pg_temp alias */
  		if (strcmp(newRelation->schemaname, "pg_temp") == 0)
  		{
  			/* Initialize temp namespace if first time through */
  			if (!TempNamespaceValid(false))
  				InitTempTableNamespace();
  			return myTempNamespace;
  		}
  		/* use exact schema given */
  		namespaceId = LookupInternalNamespaceId(newRelation->schemaname);
  
  		if (!OidIsValid(namespaceId))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_SCHEMA),
  					 errmsg("schema \"%s\" does not exist",
  							newRelation->schemaname),
  									   errOmitLocation(true)));
  		/* we do not check for USAGE rights here! */
  	}
  	else
  	{
  		if (gp_upgrade_mode)
  		{
              namespaceId = PG_CATALOG_NAMESPACE;
  		}
  		else
  		{
  			/* use the default creation namespace */
  			recomputeNamespacePath();
  			if (tempCreationPending)
  			{
  				/* Need to initialize temp namespace */
  				InitTempTableNamespace();
  				return myTempNamespace;
  			}
  			namespaceId = defaultCreationNamespace;
  		}
  
  		if (!OidIsValid(namespaceId))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_SCHEMA),
  					 errmsg("no schema has been selected to create in"),
  							   errOmitLocation(true)));
  	}
  
  	/* Note: callers will check for CREATE rights when appropriate */
  
  	return namespaceId;
  }
  
  /*
   * RelnameGetRelid
   *		Try to resolve an unqualified relation name.
   *		Returns OID if relation found in search path, else InvalidOid.
   */
  Oid
  RelnameGetRelid(const char *relname)
  {
  	Oid			relid;
  	ListCell   *l;
  
  	recomputeNamespacePath();
  
  	foreach(l, namespaceSearchPath)
  	{
  		Oid			namespaceId = lfirst_oid(l);
  
  		relid = get_relname_relid(relname, namespaceId);
  		if (OidIsValid(relid))
  			return relid;
  	}
  
  	/* Not found in path */
  	return InvalidOid;
  }
  
  
  /*
   * RelationIsVisible
   *		Determine whether a relation (identified by OID) is visible in the
   *		current search path.  Visible means "would be found by searching
   *		for the unqualified relation name".
   */
  bool
  RelationIsVisible(Oid relid)
  {
  	HeapTuple	reltup;
  	Form_pg_class relform;
  	Oid			relnamespace;
  	bool		visible;
  	cqContext  *pcqCtx;
  
  	pcqCtx = caql_beginscan(
  			NULL,
  			cql("SELECT * FROM pg_class "
  				" WHERE oid = :1 ",
  				ObjectIdGetDatum(relid)));
  
  	reltup = caql_getnext(pcqCtx);
  
  	if (!HeapTupleIsValid(reltup))
  	{
  		/* 
  		 * MPP-6982:
  		 * Note that the caller may not have gotten a lock on the relation.
  		 * Therefore, it is possible that the relation may have been dropped
  		 * by the time this method is called. Therefore, we simply return false
  		 * when we cannot find the relation in syscache instead of erroring out.
  		 */
  		return false;
  	}
  
  	relform = (Form_pg_class) GETSTRUCT(reltup);
  
  	recomputeNamespacePath();
  
  	/*
  	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
  	 * the system namespace are surely in the path and so we needn't even do
  	 * list_member_oid() for them.
  	 */
  	relnamespace = relform->relnamespace;
  	if (relnamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(namespaceSearchPath, relnamespace))
  		visible = false;
  	else
  	{
  		/*
  		 * If it is in the path, it might still not be visible; it could be
  		 * hidden by another relation of the same name earlier in the path. So
  		 * we must do a slow check for conflicting relations.
  		 */
  		char	   *relname = NameStr(relform->relname);
  		ListCell   *l;
  
  		visible = false;
  		foreach(l, namespaceSearchPath)
  		{
  			Oid			namespaceId = lfirst_oid(l);
  
  			if (namespaceId == relnamespace)
  			{
  				/* Found it first in path */
  				visible = true;
  				break;
  			}
  			if (OidIsValid(get_relname_relid(relname, namespaceId)))
  			{
  				/* Found something else first in path */
  				break;
  			}
  		}
  	}
  
  	caql_endscan(pcqCtx);
  
  	return visible;
  }
  
  
  /*
   * TypenameGetTypid
   *		Try to resolve an unqualified datatype name.
   *		Returns OID if type found in search path, else InvalidOid.
   *
   * This is essentially the same as RelnameGetRelid.
   */
  Oid
  TypenameGetTypid(const char *typname)
  {
  	Oid			typid;
  	ListCell   *l;
  
  	recomputeNamespacePath();
  
  	foreach(l, namespaceSearchPath)
  	{
  		Oid			namespaceId = lfirst_oid(l);
  
  		typid = caql_getoid(
  				NULL,
  				cql("SELECT oid FROM pg_type "
  					" WHERE typname = :1 "
  					" AND typnamespace = :2 ",
  					PointerGetDatum((char *) typname),
  					ObjectIdGetDatum(namespaceId)));
  
  		if (OidIsValid(typid))
  			return typid;
  	}
  
  	/* Not found in path */
  	return InvalidOid;
  }
  
  /*
   * TypeOidGetTypename
   * Get the name of the type, given the OID
   */
  char*
  TypeOidGetTypename(Oid typeid)
  {
  	StringInfoData tname;
  	initStringInfo(&tname);
  	
  	Assert(OidIsValid(typeid));	
  	char* typename = caql_getcstring(
  									 NULL,
  									 cql("SELECT typname FROM pg_type "
  										 " WHERE oid = :1",
  										 ObjectIdGetDatum(typeid)));
  	if (typename == NULL)
  		elog(ERROR, "oid [%u] not found in table pg_type", typeid);
  	
  	appendStringInfo(&tname, "%s", typename);
  	return tname.data;
  }
  
  /*
   * TypeIsVisible
   *		Determine whether a type (identified by OID) is visible in the
   *		current search path.  Visible means "would be found by searching
   *		for the unqualified type name".
   */
  bool
  TypeIsVisible(Oid typid)
  {
  	HeapTuple	typtup;
  	Form_pg_type typform;
  	Oid			typnamespace;
  	bool		visible;
  	cqContext  *pcqCtx;
  
  	pcqCtx = caql_beginscan(
  			NULL,
  			cql("SELECT * FROM pg_type "
  				" WHERE oid = :1 ",
  				ObjectIdGetDatum(typid)));
  
  	typtup = caql_getnext(pcqCtx);
  
  	if (!HeapTupleIsValid(typtup))
  		elog(ERROR, "cache lookup failed for type %u", typid);
  	typform = (Form_pg_type) GETSTRUCT(typtup);
  
  	recomputeNamespacePath();
  
  	/*
  	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
  	 * the system namespace are surely in the path and so we needn't even do
  	 * list_member_oid() for them.
  	 */
  	typnamespace = typform->typnamespace;
  	if (typnamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(namespaceSearchPath, typnamespace))
  		visible = false;
  	else
  	{
  		/*
  		 * If it is in the path, it might still not be visible; it could be
  		 * hidden by another type of the same name earlier in the path. So we
  		 * must do a slow check for conflicting types.
  		 */
  		char	   *typname = NameStr(typform->typname);
  		ListCell   *l;
  
  		visible = false;
  		foreach(l, namespaceSearchPath)
  		{
  			Oid			namespaceId = lfirst_oid(l);
  
  			if (namespaceId == typnamespace)
  			{
  				/* Found it first in path */
  				visible = true;
  				break;
  			}
  			
  			if (caql_getcount(
  						NULL,
  						cql("SELECT COUNT(*) FROM pg_type "
  							" WHERE typname = :1 "
  							" AND typnamespace = :2 ",
  							PointerGetDatum((char *) typname),
  							ObjectIdGetDatum(namespaceId))))
  			{
  				/* Found something else first in path */
  				break;
  			}
  		}
  	}
  
  	caql_endscan(pcqCtx);
  
  	return visible;
  }
  
  
  /*
   * FuncnameGetCandidates
   *		Given a possibly-qualified function name and argument count,
   *		retrieve a list of the possible matches.
   *
   * If nargs is -1, we return all functions matching the given name,
   * regardless of argument count.
   *
   * We search a single namespace if the function name is qualified, else
   * all namespaces in the search path.  The return list will never contain
   * multiple entries with identical argument lists --- in the multiple-
   * namespace case, we arrange for entries in earlier namespaces to mask
   * identical entries in later namespaces.
   */
  FuncCandidateList
  FuncnameGetCandidates(List *names, int nargs)
  {
  	FuncCandidateList resultList = NULL;
  	char	   *schemaname;
  	char	   *funcname;
  	Oid			namespaceId;
  	CatCList   *catlist;
  	int			i;
  
  	/* deconstruct the name list */
  	DeconstructQualifiedName(names, &schemaname, &funcname);
  
  	if (schemaname)
  	{
  		/* use exact schema given */
  		namespaceId = LookupExplicitNamespace(schemaname, NSPDBOID_CURRENT);
  	}
  	else
  	{
  		/* flag to indicate we need namespace search */
  		namespaceId = InvalidOid;
  		recomputeNamespacePath();
  	}
  
  	/* Search syscache by name only */
  
  	catlist = caql_begin_CacheList(
  			NULL,
  			cql("SELECT * FROM pg_proc "
  				" WHERE proname = :1 "
  				" ORDER BY proname, "
  				" proargtypes, "
  				" pronamespace ",
  				CStringGetDatum(funcname)));
  
  	for (i = 0; i < catlist->n_members; i++)
  	{
  		HeapTuple	proctup = &catlist->members[i]->tuple;
  		Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(proctup);
  		int			pronargs = procform->pronargs;
  		int			pathpos = 0;
  		FuncCandidateList newResult;
  
  		/* Ignore if it doesn't match requested argument count */
  		if (nargs >= 0 && pronargs != nargs)
  			continue;
  
  		if (OidIsValid(namespaceId))
  		{
  			/* Consider only procs in specified namespace */
  			if (procform->pronamespace != namespaceId)
  				continue;
  			/* No need to check args, they must all be different */
  		}
  		else
  		{
  			/*
  			 * Consider only procs that are in the search path and are not
  			 * in the temp namespace.
  			 */
  			ListCell   *nsp;
  
  			foreach(nsp, namespaceSearchPath)
  			{
  				if (procform->pronamespace == lfirst_oid(nsp) &&
  					procform->pronamespace != myTempNamespace)
  					break;
  				pathpos++;
  			}
  			if (nsp == NULL)
  				continue;		/* proc is not in search path */
  
  			/*
  			 * Okay, it's in the search path, but does it have the same
  			 * arguments as something we already accepted?	If so, keep only
  			 * the one that appears earlier in the search path.
  			 *
  			 * If we have an ordered list from caql_begin_CacheList (the normal
  			 * case), then any conflicting proc must immediately adjoin this
  			 * one in the list, so we only need to look at the newest result
  			 * item.  If we have an unordered list, we have to scan the whole
  			 * result list.
  			 */
  			if (resultList)
  			{
  				FuncCandidateList prevResult;
  
  				if (catlist->ordered)
  				{
  					if (pronargs == resultList->nargs &&
  						memcmp(procform->proargtypes.values,
  							   resultList->args,
  							   pronargs * sizeof(Oid)) == 0)
  						prevResult = resultList;
  					else
  						prevResult = NULL;
  				}
  				else
  				{
  					for (prevResult = resultList;
  						 prevResult;
  						 prevResult = prevResult->next)
  					{
  						if (pronargs == prevResult->nargs &&
  							memcmp(procform->proargtypes.values,
  								   prevResult->args,
  								   pronargs * sizeof(Oid)) == 0)
  							break;
  					}
  				}
  				if (prevResult)
  				{
  					/* We have a match with a previous result */
  					Assert(pathpos != prevResult->pathpos);
  					if (pathpos > prevResult->pathpos)
  						continue;		/* keep previous result */
  					/* replace previous result */
  					prevResult->pathpos = pathpos;
  					prevResult->oid = HeapTupleGetOid(proctup);
  					continue;	/* args are same, of course */
  				}
  			}
  		}
  
  		/*
  		 * Okay to add it to result list
  		 */
  		newResult = (FuncCandidateList)
  			palloc(sizeof(struct _FuncCandidateList) - sizeof(Oid)
  				   + pronargs * sizeof(Oid));
  		newResult->pathpos = pathpos;
  		newResult->oid = HeapTupleGetOid(proctup);
  		newResult->nargs = pronargs;
  		memcpy(newResult->args, procform->proargtypes.values,
  			   pronargs * sizeof(Oid));
  
  		newResult->next = resultList;
  		resultList = newResult;
  	}
  
  	caql_end_CacheList(catlist);
  
  	return resultList;
  }
  
  /*
   * FunctionIsVisible
   *		Determine whether a function (identified by OID) is visible in the
   *		current search path.  Visible means "would be found by searching
   *		for the unqualified function name with exact argument matches".
   */
  bool
  FunctionIsVisible(Oid funcid)
  {
  	HeapTuple	proctup;
  	Form_pg_proc procform;
  	Oid			pronamespace;
  	bool		visible;
  	cqContext  *pcqCtx;
  
  	pcqCtx = caql_beginscan(
  			NULL,
  			cql("SELECT * FROM pg_proc "
  				" WHERE oid = :1 ",
  				ObjectIdGetDatum(funcid)));
  
  	proctup = caql_getnext(pcqCtx);
  
  	if (!HeapTupleIsValid(proctup))
  		elog(ERROR, "cache lookup failed for function %u", funcid);
  	procform = (Form_pg_proc) GETSTRUCT(proctup);
  
  	recomputeNamespacePath();
  
  	/*
  	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
  	 * the system namespace are surely in the path and so we needn't even do
  	 * list_member_oid() for them.
  	 */
  	pronamespace = procform->pronamespace;
  	if (pronamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(namespaceSearchPath, pronamespace))
  		visible = false;
  	else
  	{
  		/*
  		 * If it is in the path, it might still not be visible; it could be
  		 * hidden by another proc of the same name and arguments earlier in
  		 * the path.  So we must do a slow check to see if this is the same
  		 * proc that would be found by FuncnameGetCandidates.
  		 */
  		char	   *proname = NameStr(procform->proname);
  		int			nargs = procform->pronargs;
  		FuncCandidateList clist;
  
  		visible = false;
  
  		clist = FuncnameGetCandidates(list_make1(makeString(proname)), nargs);
  
  		for (; clist; clist = clist->next)
  		{
  			if (memcmp(clist->args, procform->proargtypes.values,
  					   nargs * sizeof(Oid)) == 0)
  			{
  				/* Found the expected entry; is it the right proc? */
  				visible = (clist->oid == funcid);
  				break;
  			}
  		}
  	}
  
  	caql_endscan(pcqCtx);
  
  	return visible;
  }
  
  
  /*
   * OpernameGetOprid
   *		Given a possibly-qualified operator name and exact input datatypes,
   *		look up the operator.  Returns InvalidOid if not found.
   *
   * Pass oprleft = InvalidOid for a prefix op, oprright = InvalidOid for
   * a postfix op.
   *
   * If the operator name is not schema-qualified, it is sought in the current
   * namespace search path.
   */
  Oid
  OpernameGetOprid(List *names, Oid oprleft, Oid oprright)
  {
  	char	   *schemaname;
  	char	   *opername;
  	CatCList   *catlist;
  	ListCell   *l;
  
  	/* deconstruct the name list */
  	DeconstructQualifiedName(names, &schemaname, &opername);
  
  	if (schemaname)
  	{
  		/* search only in exact schema given */
  		Oid			namespaceId;
  		Oid			operoid;
  
  		namespaceId = LookupExplicitNamespace(schemaname, NSPDBOID_CURRENT);
  
  		operoid = caql_getoid(
  				NULL,
  				cql("SELECT oid FROM pg_operator "
  					" WHERE oprname = :1 "
  					" AND oprleft = :2 "
  					" AND oprright = :3 "
  					" AND oprnamespace = :4 ",
  					CStringGetDatum(opername),
  					ObjectIdGetDatum(oprleft),
  					ObjectIdGetDatum(oprright),
  					ObjectIdGetDatum(namespaceId)));
  
  		return operoid;
  	}
  
  	/* Search syscache by name and argument types */
  	catlist = caql_begin_CacheList(
  			NULL,
  			cql("SELECT * FROM pg_operator "
  				" WHERE oprname = :1 "
  				" AND oprleft = :2 "
  				" AND oprright = :3 "
  				" ORDER BY oprname, "
  				" oprleft, "
  				" oprright, "
  				" oprnamespace ",
  				CStringGetDatum(opername),
  				ObjectIdGetDatum(oprleft),
  				ObjectIdGetDatum(oprright)));
  
  	if (catlist->n_members == 0)
  	{
  		/* no hope, fall out early */
  		caql_end_CacheList(catlist);
  		return InvalidOid;
  	}
  
  	/*
  	 * We have to find the list member that is first in the search path, if
  	 * there's more than one.  This doubly-nested loop looks ugly, but in
  	 * practice there should usually be few catlist members.
  	 */
  	recomputeNamespacePath();
  
  	foreach(l, namespaceSearchPath)
  	{
  		Oid			namespaceId = lfirst_oid(l);
  		int			i;
  
  		if (namespaceId == myTempNamespace)
  			continue;			/* do not look in temp namespace */
  
  		for (i = 0; i < catlist->n_members; i++)
  		{
  			HeapTuple	opertup = &catlist->members[i]->tuple;
  			Form_pg_operator operform = (Form_pg_operator) GETSTRUCT(opertup);
  
  			if (operform->oprnamespace == namespaceId)
  			{
  				Oid			result = HeapTupleGetOid(opertup);
  
  				caql_end_CacheList(catlist);
  				return result;
  			}
  		}
  	}
  
  	caql_end_CacheList(catlist);
  	return InvalidOid;
  }
  
  /*
   * OpernameGetCandidates
   *		Given a possibly-qualified operator name and operator kind,
   *		retrieve a list of the possible matches.
   *
   * If oprkind is '\0', we return all operators matching the given name,
   * regardless of arguments.
   *
   * We search a single namespace if the operator name is qualified, else
   * all namespaces in the search path.  The return list will never contain
   * multiple entries with identical argument lists --- in the multiple-
   * namespace case, we arrange for entries in earlier namespaces to mask
   * identical entries in later namespaces.
   *
   * The returned items always have two args[] entries --- one or the other
   * will be InvalidOid for a prefix or postfix oprkind.	nargs is 2, too.
   */
  FuncCandidateList
  OpernameGetCandidates(List *names, char oprkind)
  {
  	FuncCandidateList resultList = NULL;
  	char	   *resultSpace = NULL;
  	int			nextResult = 0;
  	char	   *schemaname;
  	char	   *opername;
  	Oid			namespaceId;
  	CatCList   *catlist;
  	int			i;
  
  	/* deconstruct the name list */
  	DeconstructQualifiedName(names, &schemaname, &opername);
  
  	if (schemaname)
  	{
  		/* use exact schema given */
  		namespaceId = LookupExplicitNamespace(schemaname, NSPDBOID_CURRENT);
  	}
  	else
  	{
  		/* flag to indicate we need namespace search */
  		namespaceId = InvalidOid;
  		recomputeNamespacePath();
  	}
  
  	/* Search syscache by name only */
  	catlist = caql_begin_CacheList(
  			NULL, 
  			cql("SELECT * FROM pg_operator "
  				" WHERE oprname = :1 "
  				" ORDER BY oprname, "
  				" oprleft, "
  				" oprright, "
  				" oprnamespace ",
  				CStringGetDatum(opername)));
  
  	/*
  	 * In typical scenarios, most if not all of the operators found by the
  	 * catcache search will end up getting returned; and there can be quite a
  	 * few, for common operator names such as '=' or '+'.  To reduce the time
  	 * spent in palloc, we allocate the result space as an array large enough
  	 * to hold all the operators.  The original coding of this routine did a
  	 * separate palloc for each operator, but profiling revealed that the
  	 * pallocs used an unreasonably large fraction of parsing time.
  	 */
  #define SPACE_PER_OP MAXALIGN(sizeof(struct _FuncCandidateList) + sizeof(Oid))
  
  	if (catlist->n_members > 0)
  		resultSpace = palloc(catlist->n_members * SPACE_PER_OP);
  
  	for (i = 0; i < catlist->n_members; i++)
  	{
  		HeapTuple	opertup = &catlist->members[i]->tuple;
  		Form_pg_operator operform = (Form_pg_operator) GETSTRUCT(opertup);
  		int			pathpos = 0;
  		FuncCandidateList newResult;
  
  		/* Ignore operators of wrong kind, if specific kind requested */
  		if (oprkind && operform->oprkind != oprkind)
  			continue;
  
  		if (OidIsValid(namespaceId))
  		{
  			/* Consider only opers in specified namespace */
  			if (operform->oprnamespace != namespaceId)
  				continue;
  			/* No need to check args, they must all be different */
  		}
  		else
  		{
  			/*
  			 * Consider only opers that are in the search path and are not
  			 * in the temp namespace.
  			 */
  			ListCell   *nsp;
  
  			foreach(nsp, namespaceSearchPath)
  			{
  				if (operform->oprnamespace == lfirst_oid(nsp) &&
  					operform->oprnamespace != myTempNamespace)
  					break;
  				pathpos++;
  			}
  			if (nsp == NULL)
  				continue;		/* oper is not in search path */
  
  			/*
  			 * Okay, it's in the search path, but does it have the same
  			 * arguments as something we already accepted?	If so, keep only
  			 * the one that appears earlier in the search path.
  			 *
  			 * If we have an ordered list from caql_begin_CacheList (the normal
  			 * case), then any conflicting oper must immediately adjoin this
  			 * one in the list, so we only need to look at the newest result
  			 * item.  If we have an unordered list, we have to scan the whole
  			 * result list.
  			 */
  			if (resultList)
  			{
  				FuncCandidateList prevResult;
  
  				if (catlist->ordered)
  				{
  					if (operform->oprleft == resultList->args[0] &&
  						operform->oprright == resultList->args[1])
  						prevResult = resultList;
  					else
  						prevResult = NULL;
  				}
  				else
  				{
  					for (prevResult = resultList;
  						 prevResult;
  						 prevResult = prevResult->next)
  					{
  						if (operform->oprleft == prevResult->args[0] &&
  							operform->oprright == prevResult->args[1])
  							break;
  					}
  				}
  				if (prevResult)
  				{
  					/* We have a match with a previous result */
  					Assert(pathpos != prevResult->pathpos);
  					if (pathpos > prevResult->pathpos)
  						continue;		/* keep previous result */
  					/* replace previous result */
  					prevResult->pathpos = pathpos;
  					prevResult->oid = HeapTupleGetOid(opertup);
  					continue;	/* args are same, of course */
  				}
  			}
  		}
  
  		/*
  		 * Okay to add it to result list
  		 */
  		newResult = (FuncCandidateList) (resultSpace + nextResult);
  		nextResult += SPACE_PER_OP;
  
  		newResult->pathpos = pathpos;
  		newResult->oid = HeapTupleGetOid(opertup);
  		newResult->nargs = 2;
  		newResult->args[0] = operform->oprleft;
  		newResult->args[1] = operform->oprright;
  		newResult->next = resultList;
  		resultList = newResult;
  	}
  
  	caql_end_CacheList(catlist);
  
  	return resultList;
  }
  
  /*
   * OperatorIsVisible
   *		Determine whether an operator (identified by OID) is visible in the
   *		current search path.  Visible means "would be found by searching
   *		for the unqualified operator name with exact argument matches".
   */
  bool
  OperatorIsVisible(Oid oprid)
  {
  	HeapTuple	oprtup;
  	Form_pg_operator oprform;
  	Oid			oprnamespace;
  	bool		visible;
  	cqContext  *pcqCtx;
  
  	pcqCtx = caql_beginscan(
  			NULL,
  			cql("SELECT * FROM pg_operator "
  				" WHERE oid = :1 ",
  				ObjectIdGetDatum(oprid)));
  
  	oprtup = caql_getnext(pcqCtx);
  
  	if (!HeapTupleIsValid(oprtup))
  		elog(ERROR, "cache lookup failed for operator %u", oprid);
  	oprform = (Form_pg_operator) GETSTRUCT(oprtup);
  
  	recomputeNamespacePath();
  
  	/*
  	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
  	 * the system namespace are surely in the path and so we needn't even do
  	 * list_member_oid() for them.
  	 */
  	oprnamespace = oprform->oprnamespace;
  	if (oprnamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(namespaceSearchPath, oprnamespace))
  		visible = false;
  	else
  	{
  		/*
  		 * If it is in the path, it might still not be visible; it could be
  		 * hidden by another operator of the same name and arguments earlier
  		 * in the path.  So we must do a slow check to see if this is the same
  		 * operator that would be found by OpernameGetOprId.
  		 */
  		char	   *oprname = NameStr(oprform->oprname);
  
  		visible = (OpernameGetOprid(list_make1(makeString(oprname)),
  									oprform->oprleft, oprform->oprright)
  				   == oprid);
  	}
  
  	caql_endscan(pcqCtx);
  
  	return visible;
  }
  
  
  /*
   * OpclassnameGetOpcid
   *		Try to resolve an unqualified index opclass name.
   *		Returns OID if opclass found in search path, else InvalidOid.
   *
   * This is essentially the same as TypenameGetTypid, but we have to have
   * an extra argument for the index AM OID.
   */
  Oid
  OpclassnameGetOpcid(Oid amid, const char *opcname)
  {
  	Oid			opcid;
  	ListCell   *l;
  
  	recomputeNamespacePath();
  
  	foreach(l, namespaceSearchPath)
  	{
  		Oid			namespaceId = lfirst_oid(l);
  
  		if (namespaceId == myTempNamespace)
  			continue;			/* do not look in temp namespace */
  
  		opcid = caql_getoid(
  				NULL,
  				cql("SELECT oid FROM pg_opclass "
  					" WHERE opcamid = :1 "
  					" AND opcname = :2 "
  					" AND opcnamespace = :3 ",
  					ObjectIdGetDatum(amid),
  					PointerGetDatum((char *) opcname),
  					ObjectIdGetDatum(namespaceId)));
  
  		if (OidIsValid(opcid))
  			return opcid;
  	}
  
  	/* Not found in path */
  	return InvalidOid;
  }
  
  /*
   * OpclassIsVisible
   *		Determine whether an opclass (identified by OID) is visible in the
   *		current search path.  Visible means "would be found by searching
   *		for the unqualified opclass name".
   */
  bool
  OpclassIsVisible(Oid opcid)
  {
  	HeapTuple	opctup;
  	Form_pg_opclass opcform;
  	Oid			opcnamespace;
  	bool		visible;
  	cqContext  *pcqCtx;
  
  	pcqCtx = caql_beginscan(
  			NULL,
  			cql("SELECT * FROM pg_opclass "
  				" WHERE oid = :1 ",
  				ObjectIdGetDatum(opcid)));
  
  	opctup = caql_getnext(pcqCtx);
  
  	if (!HeapTupleIsValid(opctup))
  		elog(ERROR, "cache lookup failed for opclass %u", opcid);
  	opcform = (Form_pg_opclass) GETSTRUCT(opctup);
  
  	recomputeNamespacePath();
  
  	/*
  	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
  	 * the system namespace are surely in the path and so we needn't even do
  	 * list_member_oid() for them.
  	 */
  	opcnamespace = opcform->opcnamespace;
  	if (opcnamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(namespaceSearchPath, opcnamespace))
  		visible = false;
  	else
  	{
  		/*
  		 * If it is in the path, it might still not be visible; it could be
  		 * hidden by another opclass of the same name earlier in the path. So
  		 * we must do a slow check to see if this opclass would be found by
  		 * OpclassnameGetOpcid.
  		 */
  		char	   *opcname = NameStr(opcform->opcname);
  
  		visible = (OpclassnameGetOpcid(opcform->opcamid, opcname) == opcid);
  	}
  
  	caql_endscan(pcqCtx);
  
  	return visible;
  }
  
  /*
   * ConversionGetConid
   *		Try to resolve an unqualified conversion name.
   *		Returns OID if conversion found in search path, else InvalidOid.
   *
   * This is essentially the same as RelnameGetRelid.
   */
  Oid
  ConversionGetConid(const char *conname)
  {
  	Oid			conid;
  	ListCell   *l;
  
  	recomputeNamespacePath();
  
  	foreach(l, namespaceSearchPath)
  	{
  		Oid			namespaceId = lfirst_oid(l);
  
  		if (namespaceId == myTempNamespace)
  			continue;			/* do not look in temp namespace */
  
  		conid = caql_getoid(
  				NULL,
  				cql("SELECT oid FROM pg_conversion "
  					" WHERE conname = :1 "
  					" AND connamespace = :2 ",
  					PointerGetDatum((char *) conname),
  					ObjectIdGetDatum(namespaceId)));
  
  		if (OidIsValid(conid))
  			return conid;
  	}
  
  	/* Not found in path */
  	return InvalidOid;
  }
  
  /*
   * ConversionIsVisible
   *		Determine whether a conversion (identified by OID) is visible in the
   *		current search path.  Visible means "would be found by searching
   *		for the unqualified conversion name".
   */
  bool
  ConversionIsVisible(Oid conid)
  {
  	HeapTuple	contup;
  	Form_pg_conversion conform;
  	Oid			connamespace;
  	bool		visible;
  	cqContext  *pcqCtx;
  
  	pcqCtx = caql_beginscan(
  			NULL,
  			cql("SELECT * FROM pg_conversion "
  				" WHERE oid = :1 ",
  				ObjectIdGetDatum(conid)));
  
  	contup = caql_getnext(pcqCtx);
  
  	if (!HeapTupleIsValid(contup))
  		elog(ERROR, "cache lookup failed for conversion %u", conid);
  	conform = (Form_pg_conversion) GETSTRUCT(contup);
  
  	recomputeNamespacePath();
  
  	/*
  	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
  	 * the system namespace are surely in the path and so we needn't even do
  	 * list_member_oid() for them.
  	 */
  	connamespace = conform->connamespace;
  	if (connamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(namespaceSearchPath, connamespace))
  		visible = false;
  	else
  	{
  		/*
  		 * If it is in the path, it might still not be visible; it could be
  		 * hidden by another conversion of the same name earlier in the path.
  		 * So we must do a slow check to see if this conversion would be found
  		 * by ConversionGetConid.
  		 */
  		char	   *conname = NameStr(conform->conname);
  
  		visible = (ConversionGetConid(conname) == conid);
  	}
  
  	caql_endscan(pcqCtx);
  
  	return visible;
  }
  
  /*
   * DeconstructQualifiedName
   *		Given a possibly-qualified name expressed as a list of String nodes,
   *		extract the schema name and object name.
   *
   * *nspname_p is set to NULL if there is no explicit schema name.
   */
  void
  DeconstructQualifiedName(List *names,
  						 char **nspname_p,
  						 char **objname_p)
  {
  	char	   *catalogname;
  	char	   *schemaname = NULL;
  	char	   *objname = NULL;
  
  	switch (list_length(names))
  	{
  		case 1:
  			objname = strVal(linitial(names));
  			break;
  		case 2:
  			schemaname = strVal(linitial(names));
  			objname = strVal(lsecond(names));
  			break;
  		case 3:
  			catalogname = strVal(linitial(names));
  			schemaname = strVal(lsecond(names));
  			objname = strVal(lthird(names));
  
  			/*
  			 * We check the catalog name and then ignore it.
  			 */
  			if (strcmp(catalogname, get_database_name(MyDatabaseId)) != 0)
  				ereport(ERROR,
  						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				  errmsg("cross-database references are not implemented: %s",
  						 NameListToString(names))));
  			break;
  		default:
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  				errmsg("improper qualified name (too many dotted names): %s",
  					   NameListToString(names))));
  			break;
  	}
  
  	*nspname_p = schemaname;
  	*objname_p = objname;
  }
  
  
  /*
   * LookupInternalNamespaceId
   *		Look up oid of the specified internal schema .
   *
   *		Returns the namespace OID or InvalidOid if not found.
   */
  Oid
  LookupInternalNamespaceId(const char *nspname)
  {
  	return LookupNamespaceId(nspname, NSPDBOID_CURRENT);
  }
  
  /*
   * LookupNamespaceId
   *		Process an explicitly-specified schema name and database oid: 
   *		look up the schema id from the catalog
   *
   *		Returns the namespace OID or InvalidOid if not found.
   */
  Oid
  LookupNamespaceId(const char *nspname, Oid dboid)
  {
  
      /* check for pg_temp alias */
      if (NSPDBOID_CURRENT == dboid && strcmp(nspname, "pg_temp") == 0)
      {
          if (TempNamespaceValid(true))
              return myTempNamespace;
          /*
           * Since this is used only for looking up existing objects, there
           * is no point in trying to initialize the temp namespace here;
           * and doing so might create problems for some callers.
           * Just fall through and give the "does not exist" error.
           */
      }
  
      if(gp_upgrade_mode)
      {
          // This code is only need at hawq2.0 upgrade, in this case the old pg_namespace doesn't 
          // have column nspdboid, so we report error in else clause
          if(ObjectIdGetDatum(dboid)==NSPDBOID_CURRENT)
          {
              return caql_getoid(
  			NULL,
  			cql("SELECT oid FROM pg_namespace "
  				" WHERE nspname = :1",
  				CStringGetDatum((char *) nspname)));
          }
          else
          	elog(ERROR, "Upgrade cannot process the namespace: %s in dbid: %i", nspname, dboid);
      }
  	return caql_getoid(
  			NULL,
  			cql("SELECT oid FROM pg_namespace "
  				" WHERE nspname = :1 and nspdboid = :2",
  				CStringGetDatum((char *) nspname), ObjectIdGetDatum(dboid)));
  }
  
  /*
   * LookupExplicitNamespace
   *		Process an explicitly-specified schema name: look up the schema
   *		and verify we have USAGE (lookup) rights in it.
   *
   * Returns the namespace OID.  Raises ereport if any problem.
   */
  Oid
  LookupExplicitNamespace(const char *nspname, Oid dboid)
  {
  	Assert(NSPDBOID_CURRENT == dboid || HcatalogDbOid == dboid);
  	
  	Oid			namespaceId;
  	AclResult	aclresult;
  
  	namespaceId = LookupNamespaceId(nspname, dboid);
  
  	if (!OidIsValid(namespaceId))
  	{
  		if (HcatalogDbOid == dboid)
  		{
  			/* Return invalid namespaceId if in hcatalog */
  			return namespaceId;
  		}
  		StringInfoData qualifiedSchemaName;
  		initStringInfo(&qualifiedSchemaName);
  
  		appendStringInfoString(&qualifiedSchemaName, nspname);
  		
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_SCHEMA),
  				 errmsg("schema \"%s\" does not exist", qualifiedSchemaName.data),
  				 errOmitLocation(true)));
  	}
  
  	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_USAGE);
  	if (aclresult != ACLCHECK_OK)
  		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
  					   nspname);
  
  	return namespaceId;
  }
  
  /*
   * LookupCreationNamespace
   *		Look up the schema and verify we have CREATE rights on it.
   *
   * This is just like LookupExplicitNamespace except for the permission check,
   * and that we are willing to create pg_temp if needed.
   *
   * Note: calling this may result in a CommandCounterIncrement operation,
   * if we have to create or clean out the temp namespace.
   */
  Oid
  LookupCreationNamespace(const char *nspname)
  {
  	Oid			namespaceId;
  	AclResult	aclresult;
  
  	/* check for pg_temp alias */
  	if (strcmp(nspname, "pg_temp") == 0)
  	{
  		/* Initialize temp namespace if first time through */
  		if (!TempNamespaceValid(false))
  			InitTempTableNamespace();
  		return myTempNamespace;
  	}
  
  	namespaceId = LookupInternalNamespaceId((char *) nspname);
  
  	if (!OidIsValid(namespaceId))
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_SCHEMA),
  				 errmsg("schema \"%s\" does not exist", nspname),
  				 errOmitLocation(true)));
  
  	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
  	if (aclresult != ACLCHECK_OK)
  		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
  					   nspname);
  
  	return namespaceId;
  }
  
  /*
   * QualifiedNameGetCreationNamespace
   *		Given a possibly-qualified name for an object (in List-of-Values
   *		format), determine what namespace the object should be created in.
   *		Also extract and return the object name (last component of list).
   *
   * Note: this does not apply any permissions check.  Callers must check
   * for CREATE rights on the selected namespace when appropriate.
   *
   * Note: calling this may result in a CommandCounterIncrement operation,
   * if we have to create or clean out the temp namespace.
   */
  Oid
  QualifiedNameGetCreationNamespace(List *names, char **objname_p)
  {
  	char	   *schemaname;
  	Oid			namespaceId;
  
  	/* deconstruct the name list */
  	DeconstructQualifiedName(names, &schemaname, objname_p);
  
  	if (schemaname)
  	{
  		/* check for pg_temp alias */
  		if (strcmp(schemaname, "pg_temp") == 0)
  		{
  			/* Initialize temp namespace if first time through */
  			if (!TempNamespaceValid(false))
  				InitTempTableNamespace();
  			return myTempNamespace;
  		}
  		/* use exact schema given */
  		namespaceId = LookupInternalNamespaceId(schemaname);
  
  		if (!OidIsValid(namespaceId))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_SCHEMA),
  					 errmsg("schema \"%s\" does not exist", schemaname),
  				     errOmitLocation(true)));
  		/* we do not check for USAGE rights here! */
  	}
  	else
  	{
  		/* use the default creation namespace */
  		recomputeNamespacePath();
  		if (tempCreationPending)
  		{
  			/* Need to initialize temp namespace */
  			InitTempTableNamespace();
  			return myTempNamespace;
  		}
  		namespaceId = defaultCreationNamespace;
  		if (!OidIsValid(namespaceId))
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_SCHEMA),
  					 errmsg("no schema has been selected to create in")));
  	}
  
  	return namespaceId;
  }
  
  /*
   * makeRangeVarFromNameList
   *		Utility routine to convert a qualified-name list into RangeVar form.
   */
  RangeVar *
  makeRangeVarFromNameList(List *names)
  {
  	RangeVar   *rel = makeRangeVar(NULL, NULL, NULL, -1);
  
  	switch (list_length(names))
  	{
  		case 1:
  			rel->relname = strVal(linitial(names));
  			break;
  		case 2:
  			rel->schemaname = strVal(linitial(names));
  			rel->relname = strVal(lsecond(names));
  			break;
  		case 3:
  			rel->catalogname = strVal(linitial(names));
  			rel->schemaname = strVal(lsecond(names));
  			rel->relname = strVal(lthird(names));
  			break;
  		default:
  			ereport(ERROR,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  				 errmsg("improper relation name (too many dotted names): %s",
  						NameListToString(names))));
  			break;
  	}
  
  	return rel;
  }
  
  /*
   * NameListToString
   *		Utility routine to convert a qualified-name list into a string.
   *
   * This is used primarily to form error messages, and so we do not quote
   * the list elements, for the sake of legibility.
   */
  char *
  NameListToString(List *names)
  {
  	StringInfoData string;
  	ListCell   *l;
  
  	initStringInfo(&string);
  
  	foreach(l, names)
  	{
  		if (l != list_head(names))
  			appendStringInfoChar(&string, '.');
  		appendStringInfoString(&string, strVal(lfirst(l)));
  	}
  
  	return string.data;
  }
  
  /*
   * NameListToQuotedString
   *		Utility routine to convert a qualified-name list into a string.
   *
   * Same as above except that names will be double-quoted where necessary,
   * so the string could be re-parsed (eg, by textToQualifiedNameList).
   */
  char *
  NameListToQuotedString(List *names)
  {
  	StringInfoData string;
  	ListCell   *l;
  
  	initStringInfo(&string);
  
  	foreach(l, names)
  	{
  		if (l != list_head(names))
  			appendStringInfoChar(&string, '.');
  		appendStringInfoString(&string, quote_identifier(strVal(lfirst(l))));
  	}
  
  	return string.data;
  }
  
  /*
   * isTempNamespace - is the given namespace my temporary-table namespace?
   */
  bool
  isTempNamespace(Oid namespaceId)
  {
  	/* 
  	 * We know these namespaces aren't temporary. We need this bootstrapping to
  	 * avoid complex situations where we're actively trying to rebuild
  	 * pg_namespace's catalog cache but continue to recurse because
  	 * TempNamespaceValid() wants to rebuild the catalog cache for us. Chicken
  	 * and egg...
  	 */
  	if (IsBuiltInNameSpace(namespaceId))
  		return false;
  
  	if (TempNamespaceValid(false) && myTempNamespace == namespaceId)
  		return true;
  
  	return false;
  }
  
  /*
   * isAnyTempNamespace - is the given namespace a temporary-table namespace
   * (either my own, or another backend's)?
   */
  bool
  isAnyTempNamespace(Oid namespaceId)
  {
  	bool		result;
  	char	   *nspname;
  
  	/* Metadata tracking: don't check at bootstrap (before
  	 * pg_namespace is loaded 
  	 */
  	if (IsBootstrapProcessingMode())
  		return false;
  
  	/* If the namespace name starts with "pg_temp_", say "true" */
  	nspname = get_namespace_name(namespaceId);
  	if (!nspname)
  		return false;			/* no such namespace? */
  	result = (strncmp(nspname, "pg_temp_", 8) == 0);
  	pfree(nspname);
  	return result;
  }
  
  /*
   * isOtherTempNamespace - is the given namespace some other backend's
   * temporary-table namespace?
   */
  bool
  isOtherTempNamespace(Oid namespaceId)
  {
  	/* If it's my own temp namespace, say "false" */
  	if (isTempNamespace(namespaceId))
  		return false;
  	/* Else, if the namespace name starts with "pg_temp_", say "true" */
  	return isAnyTempNamespace(namespaceId);
  }
  
  /*
   * PushSpecialNamespace - push a "special" namespace onto the front of the
   * search path.
   *
   * This is a slightly messy hack intended only for support of CREATE SCHEMA.
   * Although the API is defined to allow a stack of pushed namespaces, we
   * presently only support one at a time.
   *
   * The pushed namespace will be removed from the search path at end of
   * transaction, whether commit or abort.
   */
  void
  PushSpecialNamespace(Oid namespaceId)
  {
  	Assert(!OidIsValid(mySpecialNamespace));
  	mySpecialNamespace = namespaceId;
  	namespaceSearchPathValid = false;
  }
  
  /*
   * PopSpecialNamespace - remove previously pushed special namespace.
   */
  void
  PopSpecialNamespace(Oid namespaceId)
  {
  	Assert(mySpecialNamespace == namespaceId);
  	mySpecialNamespace = InvalidOid;
  	namespaceSearchPathValid = false;
  }
  
  /*
   * FindConversionByName - find a conversion by possibly qualified name
   */
  Oid
  FindConversionByName(List *name)
  {
  	char	   *schemaname;
  	char	   *conversion_name;
  	Oid			namespaceId;
  	Oid			conoid;
  	ListCell   *l;
  
  	/* deconstruct the name list */
  	DeconstructQualifiedName(name, &schemaname, &conversion_name);
  
  	if (schemaname)
  	{
  		/* use exact schema given */
  		namespaceId = LookupExplicitNamespace(schemaname, NSPDBOID_CURRENT);
  		return FindConversion(conversion_name, namespaceId);
  	}
  	else
  	{
  		/* search for it in search path */
  		recomputeNamespacePath();
  
  		foreach(l, namespaceSearchPath)
  		{
  			namespaceId = lfirst_oid(l);
  
  			if (namespaceId == myTempNamespace)
  				continue;			/* do not look in temp namespace */
  
  			conoid = FindConversion(conversion_name, namespaceId);
  			if (OidIsValid(conoid))
  				return conoid;
  		}
  	}
  
  	/* Not found in path */
  	return InvalidOid;
  }
  
  /*
   * FindDefaultConversionProc - find default encoding conversion proc
   */
  Oid
  FindDefaultConversionProc(int4 for_encoding, int4 to_encoding)
  {
  	Oid			proc;
  	ListCell   *l;
  
  	recomputeNamespacePath();
  
  	foreach(l, namespaceSearchPath)
  	{
  		Oid			namespaceId = lfirst_oid(l);
  
  		if (namespaceId == myTempNamespace)
  			continue;			/* do not look in temp namespace */
  
  		proc = FindDefaultConversion(namespaceId, for_encoding, to_encoding);
  		if (OidIsValid(proc))
  			return proc;
  	}
  
  	/* Not found in path */
  	return InvalidOid;
  }
  
  
  
  /*
   *
   */
  static void checkNamespaceInternal(List **oidlist, Oid namespaceId, Oid roleid)
  {
  	if (pg_namespace_aclcheck(namespaceId, roleid,
  			ACL_USAGE) == ACLCHECK_OK)
  	{
  		*oidlist = lappend_oid(*oidlist, namespaceId);
  	}
  	else {
  		if (OidIsValid(namespaceId) && aclType == HAWQ_ACL_RANGER) {
  			elog(WARNING, "usage privilege of namespace %s is required.",
  					getNamespaceNameByOid(namespaceId));
  		}
  	}
  }
  /*
   * recomputeNamespacePath - recompute path derived variables if needed.
   */
  static void
  recomputeNamespacePath(void)
  {
  	Oid			roleid = GetUserId();
  	char	   *rawname;
  	List	   *namelist;
  	List	   *oidlist;
  	List	   *newpath;
  	ListCell   *l;
  	bool		temp_missing;
  	Oid			firstNS;
  	MemoryContext oldcxt;
  
  	/*
  	 * Do nothing if path is already valid.
  	 */
  	if (namespaceSearchPathValid && namespaceUser == roleid)
  	{
  		if (aclType != HAWQ_ACL_RANGER)
  		{
  			return;
  		}
  		else
  		{
  			uint32 current_query_sign = 0;
  			if (debug_query_string != NULL)
  				current_query_sign = string_hash(debug_query_string, strlen(debug_query_string));
  
  			if (current_query_sign == last_query_sign)
  				return;
  			last_query_sign = current_query_sign;
  			elog(DEBUG3, "recompute search_path[%s] when acl_type is ranger", namespace_search_path);
  		}
  	}
  	else 
  	{
  		if (aclType == HAWQ_ACL_RANGER && debug_query_string != NULL)
  		{
  			last_query_sign = string_hash(debug_query_string, strlen(debug_query_string));
  		}
  	}
  
  	/* Need a modifiable copy of namespace_search_path string */
  	rawname = pstrdup(namespace_search_path);
  
  	/* Parse string into list of identifiers */
  	if (!SplitIdentifierString(rawname, ',', &namelist))
  	{
  		/* syntax error in name list */
  		/* this should not happen if GUC checked check_search_path */
  		elog(ERROR, "invalid list syntax");
  	}
  
  	/*
  	 * Convert the list of names to a list of OIDs.  If any names are not
  	 * recognizable or we don't have read access, just leave them out of the
  	 * list.  (We can't raise an error, since the search_path setting has
  	 * already been accepted.)	Don't make duplicate entries, either.
  	 */
  	oidlist = NIL;
  	temp_missing = false;
  	foreach(l, namelist)
  	{
  		char	   *curname = (char *) lfirst(l);
  		Oid			namespaceId;
  
  		if (strcmp(curname, "$user") == 0)
  		{
  			/* $user --- substitute namespace matching user name, if any */
  			char	   *rname = NULL;
  			int			fetchCount;
  
  			rname = caql_getcstring_plus(
  					NULL,
  					&fetchCount,
  					NULL,
  					cql("SELECT rolname FROM pg_authid "
  						" WHERE oid = :1 ",
  						ObjectIdGetDatum(roleid)));
  
  			if (fetchCount)
  			{
  				namespaceId = LookupInternalNamespaceId(rname);
  
  				if (OidIsValid(namespaceId) &&
  						!list_member_oid(oidlist, namespaceId))
  				{
  					checkNamespaceInternal(&oidlist, namespaceId, roleid);
  				}
  			}
  		}
  		else if (strcmp(curname, "pg_temp") == 0)
  		{
  			/* pg_temp --- substitute temp namespace, if any */
  
  			if (TempNamespaceValid(true))
  			{
  				if (!list_member_oid(oidlist, myTempNamespace))
  					oidlist = lappend_oid(oidlist, myTempNamespace);
  			}
  			else
  			{
  				/* If it ought to be the creation namespace, set flag */
  				if (oidlist == NIL)
  					temp_missing = true;
  			}
  		}
  		else
  		{
  			/* normal namespace reference */
  			namespaceId = LookupInternalNamespaceId(curname);
  
  			if (OidIsValid(namespaceId) &&
  				!list_member_oid(oidlist, namespaceId))
  			{
  				checkNamespaceInternal(&oidlist, namespaceId, roleid);
  			}
  		}
  	}
  
  	/*
  	 * Remember the first member of the explicit list.  (Note: this is
  	 * nominally wrong if temp_missing, but we need it anyway to distinguish
  	 * explicit from implicit mention of pg_catalog.)
  	 */
  	if (oidlist == NIL)
  		firstNS = InvalidOid;
  	else
  		firstNS = linitial_oid(oidlist);
  
  	/*
  	 * Add any implicitly-searched namespaces to the list.	Note these go on
  	 * the front, not the back; also notice that we do not check USAGE
  	 * permissions for these.
  	 */
  	if (!list_member_oid(oidlist, PG_CATALOG_NAMESPACE))
  		oidlist = lcons_oid(PG_CATALOG_NAMESPACE, oidlist);
  
  	if (TempNamespaceValid(false) &&
  		!list_member_oid(oidlist, myTempNamespace))
  		oidlist = lcons_oid(myTempNamespace, oidlist);
  
  	if (OidIsValid(mySpecialNamespace) &&
  		!list_member_oid(oidlist, mySpecialNamespace))
  		oidlist = lcons_oid(mySpecialNamespace, oidlist);
  
  	/*
  	 * Now that we've successfully built the new list of namespace OIDs, save
  	 * it in permanent storage.
  	 */
  	oldcxt = MemoryContextSwitchTo(TopMemoryContext);
  	newpath = list_copy(oidlist);
  	MemoryContextSwitchTo(oldcxt);
  
  	/* Now safe to assign to state variable. */
  	list_free(namespaceSearchPath);
  	namespaceSearchPath = newpath;
  
  	/*
  	 * Update info derived from search path.
  	 */
  	firstExplicitNamespace = firstNS;
  	if (OidIsValid(mySpecialNamespace))
  	{
  		defaultCreationNamespace = mySpecialNamespace;
  		/* don't have to create temp in this state */
  		tempCreationPending = false;
  	}
  	else
  	{
  		defaultCreationNamespace = firstNS;
  		tempCreationPending = temp_missing;
  	}
  
  	/* Mark the path valid. */
  	namespaceSearchPathValid = true;
  	namespaceUser = roleid;
  
  	/* Clean up. */
  	pfree(rawname);
  	list_free(namelist);
  	list_free(oidlist);
  }
  
  /*
   * InitTempTableNamespace
   *		Initialize temp table namespace on first use in a particular backend
   */
  static void
  InitTempTableNamespace(void)
  {
  	char				 namespaceName[NAMEDATALEN];
  	int					 fetchCount;
  	char				*rolname;
  	CreateSchemaStmt   	*stmt;
  
  	Assert(!OidIsValid(myTempNamespace));
  
  	/*
  	 * First, do permission check to see if we are authorized to make temp
  	 * tables.	We use a nonstandard error message here since "databasename:
  	 * permission denied" might be a tad cryptic.
  	 *
  	 * Note that ACL_CREATE_TEMP rights are rechecked in pg_namespace_aclmask;
  	 * that's necessary since current user ID could change during the session.
  	 * But there's no need to make the namespace in the first place until a
  	 * temp table creation request is made by someone with appropriate rights.
  	 */
  	if (pg_database_aclcheck(MyDatabaseId, GetUserId(),
  							 ACL_CREATE_TEMP) != ACLCHECK_OK)
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("permission denied to create temporary tables in database \"%s\"",
  						get_database_name(MyDatabaseId))));
  
  	/* 
  	 * TempNamespace name creation rules are different depending on the
  	 * nature of the current connection role.
  	 */
  	switch (Gp_role)
  	{
  		case GP_ROLE_DISPATCH:
  			snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d", 
  					 gp_session_id);
  			break;
  
  		case GP_ROLE_UTILITY:
  			snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d", 
  					 MyBackendId);
  			break;
  
  		default:
  			/* Should never hit this */
  			elog(ERROR, "invalid backend temp schema creation");
  			break;
  	}
  
  	/*
  	 * First use of this temp namespace in this database; create it. The
  	 * temp namespaces are always owned by the superuser.  We leave their
  	 * permissions at default --- i.e., no access except to superuser ---
  	 * to ensure that unprivileged users can't peek at other backends'
  	 * temp tables.  This works because the places that access the temp
  	 * namespace for my own backend skip permissions checks on it.
  	 */
  
  	/* 
  	 * CDB: Dispatch CREATE SCHEMA command.
  	 *
  	 * We need to keep the OID of temp schemas synchronized across the
  	 * cluster which means that we must go through regular dispatch
  	 * logic rather than letting every backend manage the 
  	 */
  		
  	/* Lookup the name of the superuser */
  
  	rolname = caql_getcstring_plus(
  					NULL,
  					&fetchCount,
  					NULL,
  					cql("SELECT rolname FROM pg_authid "
  						" WHERE oid = :1 ",
  						ObjectIdGetDatum(BOOTSTRAP_SUPERUSERID)));
  
  	Assert(fetchCount);  /* bootstrap user MUST exist */
  
  	/* Execute the internal DDL */
  	stmt = makeNode(CreateSchemaStmt);
  	stmt->schemaname = namespaceName;
  	stmt->istemp	 = true;
  	stmt->authid	 = rolname;
  	ProcessUtility((Node*) stmt, "(internal create temp schema command)",
  				   NULL, false, None_Receiver, NULL);
  }
  
  /*
   * Drop temp relations for session reset.
   */
  void
  DropTempTableNamespaceForResetSession(Oid namespaceOid)
  {
    if (IsTransactionOrTransactionBlock())
      elog(ERROR, "Called within a transation");
  
    StartTransactionCommand();
  
    RemoveTempRelations(namespaceOid);
  
    CommitTransactionCommand();
  }
  
  /*
   * Called by CreateSchemaCommand when creating a temporary schema 
   */
  void
  SetTempNamespace(Oid namespaceOid)
  {
  	if (TempNamespaceValid(false))
  		elog(ERROR, "temporary namespace already exists");
  
  	/*
  	 * Okay, we've prepared the temp namespace ... but it's not committed yet,
  	 * so all our work could be undone by transaction rollback.  Set flag for
  	 * AtEOXact_Namespace to know what to do.
  	 */
  	myTempNamespace = namespaceOid;
  
  	/* It should not be done already. */
  	AssertState(myTempNamespaceSubID == InvalidSubTransactionId);
  	myTempNamespaceSubID = GetCurrentSubTransactionId();
  
  	namespaceSearchPathValid = false;	/* need to rebuild list */
  }
  
  /*
   * End-of-transaction cleanup for namespaces.
   */
  void
  AtEOXact_Namespace(bool isCommit)
  {
  	/*
  	 * If we abort the transaction in which a temp namespace was selected,
  	 * we'll have to do any creation or cleanout work over again.  So, just
  	 * forget the namespace entirely until next time.  On the other hand, if
  	 * we commit then register an exit callback to clean out the temp tables
  	 * at backend shutdown.  (We only want to register the callback once per
  	 * session, so this is a good place to do it.)
  	 */
  	if (myTempNamespaceSubID != InvalidSubTransactionId)
  	{
  		if (isCommit)
  			on_shmem_exit(RemoveTempRelationsCallback, 0);
  		else
  		{
  			myTempNamespace = InvalidOid;
  			namespaceSearchPathValid = false;	/* need to rebuild list */
  		}
  		myTempNamespaceSubID = InvalidSubTransactionId;
  	}
  
  	/*
  	 * Clean up if someone failed to do PopSpecialNamespace
  	 */
  	if (OidIsValid(mySpecialNamespace))
  	{
  		mySpecialNamespace = InvalidOid;
  		namespaceSearchPathValid = false;		/* need to rebuild list */
  	}
  }
  
  /*
   * AtEOSubXact_Namespace
   *
   * At subtransaction commit, propagate the temp-namespace-creation
   * flag to the parent subtransaction.
   *
   * At subtransaction abort, forget the flag if we set it up.
   */
  void
  AtEOSubXact_Namespace(bool isCommit, SubTransactionId mySubid,
  					  SubTransactionId parentSubid)
  {
  
      if (Gp_role == GP_ROLE_EXECUTE)
          return;
  
  	if (myTempNamespaceSubID == mySubid)
  	{
  		if (isCommit)
  			myTempNamespaceSubID = parentSubid;
  		else
  		{
  			myTempNamespaceSubID = InvalidSubTransactionId;
  			/* TEMP namespace creation failed, so reset state */
  			myTempNamespace = InvalidOid;
  			namespaceSearchPathValid = false;	/* need to rebuild list */
  		}
  	}
  }
  
  /*
   * Remove all relations in the specified temp namespace.
   *
   * This is called at backend shutdown (if we made any temp relations).
   * It is also called when we begin using a pre-existing temp namespace,
   * in order to clean out any relations that might have been created by
   * a crashed backend.
   */
  static void
  RemoveTempRelations(Oid tempNamespaceId)
  {
  	ObjectAddress object;
  
  	/*
  	 * We want to get rid of everything in the target namespace, but not the
  	 * namespace itself (deleting it only to recreate it later would be a
  	 * waste of cycles).  We do this by finding everything that has a
  	 * dependency on the namespace.
  	 */
  	object.classId = NamespaceRelationId;
  	object.objectId = tempNamespaceId;
  	object.objectSubId = 0;
  
  	deleteWhatDependsOn(&object, false);
  }
  
  /*
   * Callback to remove temp relations at backend exit.
   */
  static void
  RemoveTempRelationsCallback(int code, Datum arg)
  {
  	/*
  	 * in hawq, we do not create any object on QE,
  	 * therefore we do not drop anything.
  	 */
  	if (Gp_role == GP_ROLE_EXECUTE)
          return;
  
  	if (OidIsValid(myTempNamespace))
  	{
  		/* Need to ensure we have a usable transaction. */
  		AbortOutOfAnyTransaction();
  		StartTransactionCommand();
  
  		/* 
  		 * Make sure that the schema hasn't been removed. We must do this after
  		 * we start a new transaction (see previous two lines), otherwise we
  		 * wont have a valid CurrentResourceOwner.
  		 */
  		if (TempNamespaceValid(false))
  		{
  			RemoveTempRelations(myTempNamespace);
  
  			/* MPP-3390: drop pg_temp_N schema entry from pg_namespace */
  			RemoveSchemaById(myTempNamespace);
  			elog(DEBUG1, "Remove schema entry %u from pg_namespace", 
  				 myTempNamespace); 
  		}
  
  		CommitTransactionCommand();
  	}
  }
  
  
  /*
   * Routines for handling the GUC variable 'search_path'.
   */
  
  /* assign_hook: validate new search_path, do extra actions as needed */
  const char *
  assign_search_path(const char *newval, bool doit, GucSource source)
  {
  	char	   *rawname;
  	List	   *namelist;
  	ListCell   *l;
  
  	/* Need a modifiable copy of string */
  	rawname = pstrdup(newval);
  
  	/* Parse string into list of identifiers */
  	if (!SplitIdentifierString(rawname, ',', &namelist))
  	{
  		/* syntax error in name list */
  		pfree(rawname);
  		list_free(namelist);
  		return NULL;
  	}
  
  	/*
  	 * If we aren't inside a transaction, we cannot do database access so
  	 * cannot verify the individual names.	Must accept the list on faith.
  	 */
  	if (source >= PGC_S_INTERACTIVE && IsTransactionState())
  	{
  		/*
  		 * Verify that all the names are either valid namespace names or
  		 * "$user" or "pg_temp".  We do not require $user to correspond to a
  		 * valid namespace, and pg_temp might not exist yet.  We do not check
  		 * for USAGE rights, either; should we?
  		 *
  		 * When source == PGC_S_TEST, we are checking the argument of an ALTER
  		 * DATABASE SET or ALTER USER SET command.	It could be that the
  		 * intended use of the search path is for some other database, so we
  		 * should not error out if it mentions schemas not present in the
  		 * current database.  We reduce the message to NOTICE instead.
  		 */
  		foreach(l, namelist)
  		{
  			char	   *curname = (char *) lfirst(l);
  
  			if (strcmp(curname, "$user") == 0)
  				continue;
  			if (strcmp(curname, "pg_temp") == 0)
  				continue;
  
  			if (0 == LookupInternalNamespaceId(curname))
  			{
  				if (Gp_role != GP_ROLE_EXECUTE)
  					ereport((source == PGC_S_TEST) ? NOTICE : ERROR,
  							(errcode(ERRCODE_UNDEFINED_SCHEMA),
  							 errmsg("schema \"%s\" does not exist", curname),
  							 errOmitLocation(true)));
  			}
  		}
  	}
  
  	pfree(rawname);
  	list_free(namelist);
  
  	/*
  	 * We mark the path as needing recomputation, but don't do anything until
  	 * it's needed.  This avoids trying to do database access during GUC
  	 * initialization.
  	 */
  	if (doit)
  		namespaceSearchPathValid = false;
  
  	return newval;
  }
  
  /*
   * InitializeSearchPath: initialize module during InitPostgres.
   *
   * This is called after we are up enough to be able to do catalog lookups.
   */
  void
  InitializeSearchPath(void)
  {
  	if (IsBootstrapProcessingMode())
  	{
  		/*
  		 * In bootstrap mode, the search path must be 'pg_catalog' so that
  		 * tables are created in the proper namespace; ignore the GUC setting.
  		 */
  		MemoryContext oldcxt;
  
  		oldcxt = MemoryContextSwitchTo(TopMemoryContext);
  		namespaceSearchPath = list_make1_oid(PG_CATALOG_NAMESPACE);
  		MemoryContextSwitchTo(oldcxt);
  		defaultCreationNamespace = PG_CATALOG_NAMESPACE;
  		firstExplicitNamespace = PG_CATALOG_NAMESPACE;
  		tempCreationPending = false;
  		namespaceSearchPathValid = true;
  		namespaceUser = GetUserId();
  	}
  	else
  	{
  		/*
  		 * In normal mode, arrange for a callback on any syscache invalidation
  		 * of pg_namespace rows.
  		 */
  		CacheRegisterSyscacheCallback(NAMESPACEOID,
  									  NamespaceCallback,
  									  (Datum) 0);
  		/* Force search path to be recomputed on next use */
  		namespaceSearchPathValid = false;
  	}
  }
  
  /*
   * NamespaceCallback
   *		Syscache inval callback function
   */
  static void
  NamespaceCallback(Datum arg, Oid relid)
  {
  	/* Force search path to be recomputed on next use */
  	namespaceSearchPathValid = false;
  }
  
  /* double check that temp name space is valid. */
  static bool
  TempNamespaceValid(bool error_if_removed)
  {
  	if (!OidIsValid(myTempNamespace))
  		return false;
  	else
  	{
  		/*
  		 * Warning:  To use the syscache, there must be a valid ResourceOwner.
  		 * This implies we must be in a Portal, and if we are in a
  		 * Portal, we are in a transaction.  So you can't use this if
  		 * we are currently idle.
  		 */
  		AcceptInvalidationMessages();  /* minimize race conditions */
  
  		/* NOTE: use of syscache with caql ! */
  		/* XXX XXX: jic 20120430: is this correct - check if oid exists? */
  		myTempNamespace = caql_getoid(
  				NULL,
  				cql("SELECT oid FROM pg_namespace "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(myTempNamespace)));
  
  		if (OidIsValid(myTempNamespace))
  			return true;
  		else if (Gp_role != GP_ROLE_EXECUTE && error_if_removed) 
  			/*
  			 * We might call this on QEs if we're dropping our own
  			 * session's temp table schema. However, we want the
  			 * QD to be the one to find it not the QE.
  			 */
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_SCHEMA),
  					 errmsg("temporary table schema removed while session "
  							"still in progress")));
  	}
  	return false;
  }
  
  /*
   * GPDB: Special just for cdbgang use
   */
  bool
  TempNamespaceOidIsValid(void)
  {
  	return OidIsValid(myTempNamespace);
  }
  
  /*
   * Fetch the active search path. The return value is a palloc'ed list
   * of OIDs; the caller is responsible for freeing this storage as
   * appropriate.
   *
   * The returned list includes the implicitly-prepended namespaces only if
   * includeImplicit is true.
   *
   * Note: calling this may result in a CommandCounterIncrement operation,
   * if we have to create or clean out the temp namespace.
   */
  List *
  fetch_search_path(bool includeImplicit)
  {
  	List	   *result;
  
  	recomputeNamespacePath();
  
  	/*
  	 * If the temp namespace should be first, force it to exist.  This is
  	 * so that callers can trust the result to reflect the actual default
  	 * creation namespace.  It's a bit bogus to do this here, since
  	 * current_schema() is supposedly a stable function without side-effects,
  	 * but the alternatives seem worse.
  	 */
  	if (tempCreationPending)
  	{
  		InitTempTableNamespace();
  		recomputeNamespacePath();
  	}
  
  	result = list_copy(namespaceSearchPath);
  	if (!includeImplicit)
  	{
  		while (result && linitial_oid(result) != firstExplicitNamespace)
  			result = list_delete_first(result);
  	}
  
  	return result;
  }
  
  /*
   * Export the FooIsVisible functions as SQL-callable functions.
   *
   * Note: as of Postgres 8.4, these will silently return NULL if called on
   * a nonexistent object OID, rather than failing.  This is to avoid race
   * condition errors when a query that's scanning a catalog using an MVCC
   * snapshot uses one of these functions.  The underlying IsVisible functions
   * operate on SnapshotNow semantics and so might see the object as already
   * gone when it's still visible to the MVCC snapshot.  (There is no race
   * condition in the current coding because we don't accept sinval messages
   * between the searchsyscacheexists/getcount test and the subsequent lookup.)
   */
  
  Datum
  pg_table_is_visible(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	if (0 == caql_getcount(
  				NULL,
  				cql("SELECT COUNT(*) FROM pg_class "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(oid))))
  		PG_RETURN_NULL();
  
  	PG_RETURN_BOOL(RelationIsVisible(oid));
  }
  
  Datum
  pg_type_is_visible(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	if (0 == caql_getcount(
  				NULL,
  				cql("SELECT COUNT(*) FROM pg_type "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(oid))))
  		PG_RETURN_NULL();
  
  	PG_RETURN_BOOL(TypeIsVisible(oid));
  }
  
  Datum
  pg_function_is_visible(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	if (0 == caql_getcount(
  				NULL,
  				cql("SELECT COUNT(*) FROM pg_proc "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(oid))))
  		PG_RETURN_NULL();
  
  	PG_RETURN_BOOL(FunctionIsVisible(oid));
  }
  
  Datum
  pg_operator_is_visible(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	if (0 == caql_getcount(
  				NULL,
  				cql("SELECT COUNT(*) FROM pg_operator "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(oid))))
  		PG_RETURN_NULL();
  
  	PG_RETURN_BOOL(OperatorIsVisible(oid));
  }
  
  Datum
  pg_opclass_is_visible(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	if (0 == caql_getcount(
  				NULL,
  				cql("SELECT COUNT(*) FROM pg_opclass "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(oid))))
  		PG_RETURN_NULL();
  
  	PG_RETURN_BOOL(OpclassIsVisible(oid));
  }
  
  Datum
  pg_conversion_is_visible(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	if (0 == caql_getcount(
  				NULL,
  				cql("SELECT COUNT(*) FROM pg_conversion "
  					" WHERE oid = :1 ",
  					ObjectIdGetDatum(oid))))
  		PG_RETURN_NULL();
  
  	PG_RETURN_BOOL(ConversionIsVisible(oid));
  }
  
  Datum
  pg_my_temp_schema(PG_FUNCTION_ARGS)
  {
  	PG_RETURN_OID(myTempNamespace);
  }
  
  Datum
  pg_is_other_temp_schema(PG_FUNCTION_ARGS)
  {
  	Oid			oid = PG_GETARG_OID(0);
  
  	PG_RETURN_BOOL(isOtherTempNamespace(oid));
  }
  
  Datum
  pg_objname_to_oid(PG_FUNCTION_ARGS)
  {
      text *s = PG_GETARG_TEXT_P(0); 
      RangeVar *rv = makeRangeVarFromNameList(textToQualifiedNameList(s));
      Oid relid = RangeVarGetRelid(rv, true, false /*allowHcatalog*/);
  
      PG_RETURN_OID(relid);
  }
  
      
      
  