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) 2012-2014, TransLattice, Inc.
   * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * IDENTIFICATION
   *      src/backend/catalog/namespace.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/htup_details.h"
  #include "access/parallel.h"
  #include "access/xact.h"
  #ifdef PGXC
  #include "access/transam.h"
  #include "pgxc/pgxc.h"
  #endif
  #include "access/xlog.h"
  #include "catalog/dependency.h"
  #include "catalog/objectaccess.h"
  #include "catalog/pg_authid.h"
  #include "catalog/pg_collation.h"
  #include "catalog/pg_conversion.h"
  #include "catalog/pg_conversion_fn.h"
  #include "catalog/pg_namespace.h"
  #include "catalog/pg_opclass.h"
  #include "catalog/pg_operator.h"
  #include "catalog/pg_opfamily.h"
  #include "catalog/pg_proc.h"
  #include "catalog/pg_statistic_ext.h"
  #include "catalog/pg_ts_config.h"
  #include "catalog/pg_ts_dict.h"
  #include "catalog/pg_ts_parser.h"
  #include "catalog/pg_ts_template.h"
  #include "catalog/pg_type.h"
  #include "commands/dbcommands.h"
  #include "funcapi.h"
  #include "mb/pg_wchar.h"
  #include "miscadmin.h"
  #include "nodes/makefuncs.h"
  #include "parser/parse_func.h"
  #include "storage/ipc.h"
  #include "storage/lmgr.h"
  #ifdef XCP
  #include "storage/proc.h"
  #endif
  #include "storage/sinval.h"
  #include "utils/acl.h"
  #include "utils/builtins.h"
  #include "utils/catcache.h"
  #include "utils/guc.h"
  #include "utils/inval.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
  #include "utils/syscache.h"
  #include "utils/varlena.h"
  
  #ifdef _PG_ORCL_
  #include "catalog/catalog.h"
  #endif
  
  /*
   * The namespace search path is a possibly-empty list of namespace OIDs.
   * In addition to the explicit list, implicitly-searched namespaces
   * may be included:
   *
   * 1. If a TEMP table namespace has been initialized in this session, it
   * is implicitly searched first.  (The only time this doesn't happen is
   * when we are obeying an override search path spec that says not to use the
   * temp namespace, or the temp namespace is included in the explicit list.)
   *
   * 2. 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 always the first element of the
   * explicit list.  If the explicit list is empty, 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.)
   * activeTempCreationPending is TRUE if "pg_temp" appears first in the string
   * but is not reflected in activeCreationNamespace 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.
   * initdb 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).
   *
   * We support a stack of "override" search path settings for use within
   * specific sections of backend code.  namespace_search_path is ignored
   * whenever the override stack is nonempty.  activeSearchPath is always
   * the actually active path; it points either to the search list of the
   * topmost stack entry, or to baseSearchPath which is the list derived
   * from namespace_search_path.
   *
   * If baseSearchPathValid is false, then baseSearchPath (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 non-overridden lookup attempt.  Note that an
   * override spec is never subject to recomputation.
   *
   * Any namespaces mentioned in namespace_search_path that are not readable
   * by the current user ID are simply left out of baseSearchPath; so
   * we have to be willing to recompute the path when current userid changes.
   * namespaceUser is the userid the path has been computed for.
   *
   * Note: all data pointed to by these List variables is in TopMemoryContext.
   */
  
  /* These variables define the actually active state: */
  
  static List *activeSearchPath = NIL;
  
  /* default place to create stuff; if InvalidOid, no default */
  static Oid    activeCreationNamespace = InvalidOid;
  
  /* if TRUE, activeCreationNamespace is wrong, it should be temp namespace */
  static bool activeTempCreationPending = false;
  
  /* These variables are the values last derived from namespace_search_path: */
  
  static List *baseSearchPath = NIL;
  
  static Oid    baseCreationNamespace = InvalidOid;
  
  static bool baseTempCreationPending = false;
  
  static Oid    namespaceUser = InvalidOid;
  
  /* The above four values are valid only if baseSearchPathValid */
  static bool baseSearchPathValid = true;
  
  /* Override requests are remembered in a stack of OverrideStackEntry structs */
  
  typedef struct
  {
      List       *searchPath;        /* the desired search path */
      Oid            creationNamespace;    /* the desired creation namespace */
      int            nestLevel;        /* subtransaction nesting level */
  } OverrideStackEntry;
  
  static List *overrideStack = NIL;
  
  /*
   * 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.
   *
   * myTempToastNamespace is the OID of the namespace for my temp tables' toast
   * tables.  It is set when myTempNamespace is, and is InvalidOid before that.
   *
   * 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 Oid    myTempToastNamespace = InvalidOid;
  
  static SubTransactionId myTempNamespaceSubID = InvalidSubTransactionId;
  
  /*
   * This is the user's textual search path specification --- it's the value
   * of the GUC variable 'search_path'.
   */
  char       *namespace_search_path = NULL;
  
  
  /* Local functions */
  static void recomputeNamespacePath(void);
  static void InitTempTableNamespace(void);
  static void RemoveTempRelations(Oid tempNamespaceId);
  static void RemoveTempRelationsCallback(int code, Datum arg);
  static void NamespaceCallback(Datum arg, int cacheid, uint32 hashvalue);
  static bool MatchNamedCall(HeapTuple proctup, int nargs, List *argnames,
                 int **argnumbers);
  
  #ifdef _MLS_
  static List * FunctionGetOidsByNameInner(char *schemaname, char * funcname);
  static void StringDeconstructQualifiedName(List *names,
                           char **nspname_p,
                           char **objname_p);
  
  #endif
  
  #ifdef XCP
  static void FindTemporaryNamespace(void);
  #endif
  
  
  /*
   * RangeVarGetRelid
   *        Given a RangeVar describing an existing relation,
   *        select the proper namespace and look up the relation OID.
   *
   * If the schema or relation is not found, return InvalidOid if missing_ok
   * = true, otherwise raise an error.
   *
   * If nowait = true, throw an error if we'd have to wait for a lock.
   *
   * Callback allows caller to check permissions or acquire additional locks
   * prior to grabbing the relation lock.
   */
  Oid
  RangeVarGetRelidExtended(const RangeVar *relation, LOCKMODE lockmode,
                           bool missing_ok, bool nowait,
                           RangeVarGetRelidCallback callback, void *callback_arg)
  {// #lizard forgives
      uint64        inval_count;
      Oid            relId;
      Oid            oldRelId = InvalidOid;
      bool        retry = false;
  
      /*
       * We check the catalog name and then ignore it.
       */
      if (relation->catalogname)
      {
          if (strcmp(relation->catalogname, get_database_name(MyDatabaseId)) != 0)
              ereport(ERROR,
                      (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                       errmsg("cross-database references are not implemented: \"%s.%s.%s\"",
                              relation->catalogname, relation->schemaname,
                              relation->relname)));
      }
  
      /*
       * DDL operations can change the results of a name lookup.  Since all such
       * operations will generate invalidation messages, we keep track of
       * whether any such messages show up while we're performing the operation,
       * and retry until either (1) no more invalidation messages show up or (2)
       * the answer doesn't change.
       *
       * But if lockmode = NoLock, then we assume that either the caller is OK
       * with the answer changing under them, or that they already hold some
       * appropriate lock, and therefore return the first answer we get without
       * checking for invalidation messages.  Also, if the requested lock is
       * already held, LockRelationOid will not AcceptInvalidationMessages, so
       * we may fail to notice a change.  We could protect against that case by
       * calling AcceptInvalidationMessages() before beginning this loop, but
       * that would add a significant amount overhead, so for now we don't.
       */
      for (;;)
      {
          /*
           * Remember this value, so that, after looking up the relation name
           * and locking its OID, we can check whether any invalidation messages
           * have been processed that might require a do-over.
           */
          inval_count = SharedInvalidMessageCounter;
  
          /*
           * Some non-default relpersistence value may have been specified.  The
           * parser never generates such a RangeVar in simple DML, but it can
           * happen in contexts such as "CREATE TEMP TABLE foo (f1 int PRIMARY
           * KEY)".  Such a command will generate an added CREATE INDEX
           * operation, which must be careful to find the temp table, even when
           * pg_temp is not first in the search path.
           */
          if (relation->relpersistence == RELPERSISTENCE_TEMP)
          {
              if (!OidIsValid(myTempNamespace))
                  relId = InvalidOid; /* this probably can't happen? */
              else
              {
                  if (relation->schemaname)
                  {
                      Oid            namespaceId;
  
                      namespaceId = LookupExplicitNamespace(relation->schemaname, missing_ok);
  
                      /*
                       * For missing_ok, allow a non-existent schema name to
                       * return InvalidOid.
                       */
                      if (namespaceId != myTempNamespace)
                          ereport(ERROR,
                                  (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                                   errmsg("temporary tables cannot specify a schema name")));
                  }
  
                  relId = get_relname_relid(relation->relname, myTempNamespace);
              }
          }
          else if (relation->schemaname)
          {
              Oid            namespaceId;
  
              /* use exact schema given */
              namespaceId = LookupExplicitNamespace(relation->schemaname, missing_ok);
              if (missing_ok && !OidIsValid(namespaceId))
                  relId = InvalidOid;
              else
                  relId = get_relname_relid(relation->relname, namespaceId);
          }
          else
          {
              /* search the namespace path */
              relId = RelnameGetRelid(relation->relname);
          }
  
          /*
           * Invoke caller-supplied callback, if any.
           *
           * This callback is a good place to check permissions: we haven't
           * taken the table lock yet (and it's really best to check permissions
           * before locking anything!), but we've gotten far enough to know what
           * OID we think we should lock.  Of course, concurrent DDL might
           * change things while we're waiting for the lock, but in that case
           * the callback will be invoked again for the new OID.
           */
          if (callback)
              callback(relation, relId, oldRelId, callback_arg);
  
          /*
           * If no lock requested, we assume the caller knows what they're
           * doing.  They should have already acquired a heavyweight lock on
           * this relation earlier in the processing of this same statement, so
           * it wouldn't be appropriate to AcceptInvalidationMessages() here, as
           * that might pull the rug out from under them.
           */
          if (lockmode == NoLock)
              break;
  
          /*
           * If, upon retry, we get back the same OID we did last time, then the
           * invalidation messages we processed did not change the final answer.
           * So we're done.
           *
           * If we got a different OID, we've locked the relation that used to
           * have this name rather than the one that does now.  So release the
           * lock.
           */
          if (retry)
          {
              if (relId == oldRelId)
                  break;
              if (OidIsValid(oldRelId))
                  UnlockRelationOid(oldRelId, lockmode);
          }
  
          /*
           * Lock relation.  This will also accept any pending invalidation
           * messages.  If we got back InvalidOid, indicating not found, then
           * there's nothing to lock, but we accept invalidation messages
           * anyway, to flush any negative catcache entries that may be
           * lingering.
           */
          if (!OidIsValid(relId))
              AcceptInvalidationMessages();
          else if (!nowait)
              LockRelationOid(relId, lockmode);
          else if (!ConditionalLockRelationOid(relId, lockmode))
          {
              if (relation->schemaname)
                  ereport(ERROR,
                          (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
                           errmsg("could not obtain lock on relation \"%s.%s\"",
                                  relation->schemaname, relation->relname)));
              else
                  ereport(ERROR,
                          (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
                           errmsg("could not obtain lock on relation \"%s\"",
                                  relation->relname)));
          }
  
          /*
           * If no invalidation message were processed, we're done!
           */
          if (inval_count == SharedInvalidMessageCounter)
              break;
  
          /*
           * Something may have changed.  Let's repeat the name lookup, to make
           * sure this name still references the same relation it did
           * previously.
           */
          retry = true;
          oldRelId = relId;
      }
  
      if (!OidIsValid(relId) && !missing_ok)
      {
          if (relation->schemaname)
              ereport(ERROR,
                      (errcode(ERRCODE_UNDEFINED_TABLE),
                       errmsg("relation \"%s.%s\" does not exist",
                              relation->schemaname, relation->relname)));
          else
              ereport(ERROR,
                      (errcode(ERRCODE_UNDEFINED_TABLE),
                       errmsg("relation \"%s\" does not exist",
                              relation->relname)));
      }
  
  #ifdef __TBASE__
      if (OidIsValid(relId) && lockmode != NoLock)
      {
          Oid parentId = get_interval_parent_relid(relId);
  
          if (OidIsValid(parentId))
          {
              LockRelationOid(parentId, AccessShareLock);
          }
      }
  #endif
  
      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)
  {// #lizard forgives
      Oid            namespaceId;
  
      /*
       * We check the catalog name and then ignore it.
       */
      if (newRelation->catalogname)
      {
          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->schemaname)
      {
          /* check for pg_temp alias */
          if (strcmp(newRelation->schemaname, "pg_temp") == 0)
          {
              /* Initialize temp namespace if first time through */
              if (!OidIsValid(myTempNamespace))
                  InitTempTableNamespace();
              return myTempNamespace;
          }
          /* use exact schema given */
          namespaceId = get_namespace_oid(newRelation->schemaname, false);
          /* we do not check for USAGE rights here! */
      }
      else if (newRelation->relpersistence == RELPERSISTENCE_TEMP)
      {
          /* Initialize temp namespace if first time through */
          if (!OidIsValid(myTempNamespace))
              InitTempTableNamespace();
          return myTempNamespace;
      }
      else
      {
          /* use the default creation namespace */
          recomputeNamespacePath();
          if (activeTempCreationPending)
          {
              /* Need to initialize temp namespace */
              InitTempTableNamespace();
              return myTempNamespace;
          }
          namespaceId = activeCreationNamespace;
          if (!OidIsValid(namespaceId))
              ereport(ERROR,
                      (errcode(ERRCODE_UNDEFINED_SCHEMA),
                       errmsg("no schema has been selected to create in")));
      }
  
      /* Note: callers will check for CREATE rights when appropriate */
  
      return namespaceId;
  }
  
  /*
   * RangeVarGetAndCheckCreationNamespace
   *
   * This function returns the OID of the namespace in which a new relation
   * with a given name should be created.  If the user does not have CREATE
   * permission on the target namespace, this function will instead signal
   * an ERROR.
   *
   * If non-NULL, *existing_oid is set to the OID of any existing relation with
   * the same name which already exists in that namespace, or to InvalidOid if
   * no such relation exists.
   *
   * If lockmode != NoLock, the specified lock mode is acquired on the existing
   * relation, if any, provided that the current user owns the target relation.
   * However, if lockmode != NoLock and the user does not own the target
   * relation, we throw an ERROR, as we must not try to lock relations the
   * user does not have permissions on.
   *
   * As a side effect, this function acquires AccessShareLock on the target
   * namespace.  Without this, the namespace could be dropped before our
   * transaction commits, leaving behind relations with relnamespace pointing
   * to a no-longer-existent namespace.
   *
   * As a further side-effect, if the selected namespace is a temporary namespace,
   * we mark the RangeVar as RELPERSISTENCE_TEMP.
   */
  Oid
  RangeVarGetAndCheckCreationNamespace(RangeVar *relation,
                                       LOCKMODE lockmode,
                                       Oid *existing_relation_id)
  {// #lizard forgives
      uint64        inval_count;
      Oid            relid;
      Oid            oldrelid = InvalidOid;
      Oid            nspid;
      Oid            oldnspid = InvalidOid;
      bool        retry = false;
  
      /*
       * We check the catalog name and then ignore it.
       */
      if (relation->catalogname)
      {
          if (strcmp(relation->catalogname, get_database_name(MyDatabaseId)) != 0)
              ereport(ERROR,
                      (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                       errmsg("cross-database references are not implemented: \"%s.%s.%s\"",
                              relation->catalogname, relation->schemaname,
                              relation->relname)));
      }
  
      /*
       * As in RangeVarGetRelidExtended(), we guard against concurrent DDL
       * operations by tracking whether any invalidation messages are processed
       * while we're doing the name lookups and acquiring locks.  See comments
       * in that function for a more detailed explanation of this logic.
       */
      for (;;)
      {
          AclResult    aclresult;
  
          inval_count = SharedInvalidMessageCounter;
  
          /* Look up creation namespace and check for existing relation. */
          nspid = RangeVarGetCreationNamespace(relation);
          Assert(OidIsValid(nspid));
          if (existing_relation_id != NULL)
              relid = get_relname_relid(relation->relname, nspid);
          else
              relid = InvalidOid;
  
          /*
           * In bootstrap processing mode, we don't bother with permissions or
           * locking.  Permissions might not be working yet, and locking is
           * unnecessary.
           */
          if (IsBootstrapProcessingMode())
              break;
  
          /* Check namespace permissions. */
          aclresult = pg_namespace_aclcheck(nspid, GetUserId(), ACL_CREATE);
          if (aclresult != ACLCHECK_OK)
              aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
                             get_namespace_name(nspid));
  
          if (retry)
          {
              /* If nothing changed, we're done. */
              if (relid == oldrelid && nspid == oldnspid)
                  break;
              /* If creation namespace has changed, give up old lock. */
              if (nspid != oldnspid)
                  UnlockDatabaseObject(NamespaceRelationId, oldnspid, 0,
                                       AccessShareLock);
              /* If name points to something different, give up old lock. */
              if (relid != oldrelid && OidIsValid(oldrelid) && lockmode != NoLock)
                  UnlockRelationOid(oldrelid, lockmode);
          }
  
          /* Lock namespace. */
          if (nspid != oldnspid)
              LockDatabaseObject(NamespaceRelationId, nspid, 0, AccessShareLock);
  
          /* Lock relation, if required if and we have permission. */
          if (lockmode != NoLock && OidIsValid(relid))
          {
              if (!pg_class_ownercheck(relid, GetUserId()))
                  aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 relation->relname);
              if (relid != oldrelid)
                  LockRelationOid(relid, lockmode);
          }
  
          /* If no invalidation message were processed, we're done! */
          if (inval_count == SharedInvalidMessageCounter)
              break;
  
          /* Something may have changed, so recheck our work. */
          retry = true;
          oldrelid = relid;
          oldnspid = nspid;
      }
  
      RangeVarAdjustRelationPersistence(relation, nspid);
      if (existing_relation_id != NULL)
          *existing_relation_id = relid;
      return nspid;
  }
  
  /*
   * Adjust the relpersistence for an about-to-be-created relation based on the
   * creation namespace, and throw an error for invalid combinations.
   */
  void
  RangeVarAdjustRelationPersistence(RangeVar *newRelation, Oid nspid)
  {
      switch (newRelation->relpersistence)
      {
          case RELPERSISTENCE_TEMP:
              if (!isTempOrTempToastNamespace(nspid))
              {
                  if (isAnyTempNamespace(nspid))
                      ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("cannot create relations in temporary schemas of other sessions")));
                  else
                      ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("cannot create temporary relation in non-temporary schema")));
              }
              break;
          case RELPERSISTENCE_PERMANENT:
              if (isTempOrTempToastNamespace(nspid))
                  newRelation->relpersistence = RELPERSISTENCE_TEMP;
              else if (isAnyTempNamespace(nspid))
                  ereport(ERROR,
                          (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                           errmsg("cannot create relations in temporary schemas of other sessions")));
              break;
          default:
              if (isAnyTempNamespace(nspid))
                  ereport(ERROR,
                          (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                           errmsg("only temporary relations may be created in temporary schemas")));
      }
  }
  
  /*
   * 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, activeSearchPath)
      {
          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;
  
      reltup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
      if (!HeapTupleIsValid(reltup))
          elog(ERROR, "cache lookup failed for relation %u", relid);
      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(activeSearchPath, 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, activeSearchPath)
          {
              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;
              }
          }
      }
  
      ReleaseSysCache(reltup);
  
      return visible;
  }
  /*
   * TypIDGetTypename
   *		Try to resolve an OID.
   *		Returns typename if type found in search path
   * 		else, schema.typename.
   *
   */
  char *
  TypidGetTypename(Oid typid) 
  {
  	HeapTuple		tuple;
  	Form_pg_type	typeForm;
  	char		   *result;
  	char 			prefix[2*NAMEDATALEN+2];
  	char 			*typnspname;
  	Oid				typnamespace;
  
  	tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
  
  	if (!HeapTupleIsValid(tuple))
  			elog(ERROR, "cache lookup failed for type %u", typid);
  
  	typeForm = (Form_pg_type) GETSTRUCT(tuple);
  	typnamespace = typeForm->typnamespace;
  	if (typnamespace != PG_CATALOG_NAMESPACE &&
  		!list_member_oid(activeSearchPath, typnamespace))
  	{
  		typnspname = get_namespace_name(typeForm->typnamespace);
  		sprintf(prefix, "%s.%s", typnspname, NameStr(typeForm->typname));
  		result = pstrdup(prefix);	
  	}
  	else 
  	{
  		result = pstrdup(NameStr(typeForm->typname));
  	}
  
  	ReleaseSysCache(tuple);
  
  	return result;
  }
  
  /*
   * 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, activeSearchPath)
      {
          Oid            namespaceId = lfirst_oid(l);
  
          typid = GetSysCacheOid2(TYPENAMENSP,
                                  PointerGetDatum(typname),
                                  ObjectIdGetDatum(namespaceId));
          if (OidIsValid(typid))
              return typid;
      }
  
      /* Not found in path */
      return InvalidOid;
  }
  
  /*
   * 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;
  
      typtup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
      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(activeSearchPath, 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, activeSearchPath)
          {
              Oid            namespaceId = lfirst_oid(l);
  
              if (namespaceId == typnamespace)
              {
                  /* Found it first in path */
                  visible = true;
                  break;
              }
              if (SearchSysCacheExists2(TYPENAMENSP,
                                        PointerGetDatum(typname),
                                        ObjectIdGetDatum(namespaceId)))
              {
                  /* Found something else first in path */
                  break;
              }
          }
      }
  
      ReleaseSysCache(typtup);
  
      return visible;
  }
  
  #ifdef __AUDIT__
  List * 
  FunctionGetOidsByName(List * func_name)
  {// #lizard forgives
      char       *schemaname = NULL;
      char       *funcname = NULL;
      Oid            namespaceId = InvalidOid;
      CatCList   *catlist = NULL;
      int            i= 0;
      List        *loid = NIL;
      bool        found = false;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(func_name, &schemaname, &funcname);
  
      if (schemaname != NULL)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, false);
          if (!OidIsValid(namespaceId))
          {
              ereport(ERROR,
                      (errcode(ERRCODE_UNDEFINED_SCHEMA),
                       errmsg("schema \"%s\" does not exist", schemaname)));
              return NULL;
          }
      }
      else
      {
          /* flag to indicate we need namespace search */
          namespaceId = InvalidOid;
          recomputeNamespacePath();
      }
  
      /* Search syscache by name only */
      catlist = SearchSysCacheList1(PROCNAMEARGSNSP, 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);
          Oid procoid = HeapTupleGetOid(proctup);
  
          if (OidIsValid(namespaceId))
          {
              /* Consider only procs in specified namespace */
              if (procform->pronamespace != namespaceId)
                  continue;
          }
          else
          {
              /*
               * Consider only procs that are in the search path and are not in
               * the temp namespace.
               */
              ListCell   *nsp = NULL;
  
              foreach(nsp, activeSearchPath)
              {
                  if (procform->pronamespace == lfirst_oid(nsp) &&
                      procform->pronamespace != myTempNamespace)
                      break;
              }
              if (nsp == NULL)
                  continue;        /* proc is not in search path */
          }
  
          loid = list_append_unique_oid(loid, procoid);
          found = true;
      }
  
      ReleaseSysCacheList(catlist);
  
      if (!found)
      {
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_FUNCTION),
                   errmsg("\"%s\" is not a function",
                          NameListToString(func_name))));
          return NIL;
      }
  
      return loid;
  }
  
  char * RangeVarGetName(RangeVar *relation)
  {
      StringInfo str = makeStringInfo();
  
      if (relation->catalogname != NULL &&
          relation->schemaname != NULL)
      {
          appendStringInfo(str, "%s.%s.%s", 
                           relation->catalogname,
                           relation->schemaname,
                           relation->relname);
      }
      else if (relation->schemaname != NULL)
      {
          appendStringInfo(str, "%s.%s", 
                           relation->schemaname,
                           relation->relname);
      }
      else
      {
          appendStringInfo(str, "%s", 
                           relation->relname);
      }
  
      return str->data;
  }
  
  #endif
  #ifdef  _MLS_
  static List * FunctionGetOidsByNameInner(char *schemaname, char * funcname)
  {// #lizard forgives
      Oid            namespaceId = InvalidOid;
      CatCList   *catlist = NULL;
      int            i= 0;
      List        *loid = NIL;
      bool        found = false;
  
      if (schemaname != NULL)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, false);
          if (!OidIsValid(namespaceId))
          {
              ereport(ERROR,
                      (errcode(ERRCODE_UNDEFINED_SCHEMA),
                       errmsg("schema \"%s\" does not exist", schemaname)));
              return NULL;
          }
      }
      else
      {
          /* flag to indicate we need namespace search */
          namespaceId = InvalidOid;
          recomputeNamespacePath();
      }
  
      Assert(funcname);
  
      /* Search syscache by name only */
      catlist = SearchSysCacheList1(PROCNAMEARGSNSP, 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);
          Oid procoid = HeapTupleGetOid(proctup);
  
          if (OidIsValid(namespaceId))
          {
              /* Consider only procs in specified namespace */
              if (procform->pronamespace != namespaceId)
                  continue;
          }
          else
          {
              /*
               * Consider only procs that are in the search path and are not in
               * the temp namespace.
               */
              ListCell   *nsp = NULL;
  
              foreach(nsp, activeSearchPath)
              {
                  if (procform->pronamespace == lfirst_oid(nsp) &&
                      procform->pronamespace != myTempNamespace)
                      break;
              }
              if (nsp == NULL)
                  continue;        /* proc is not in search path */
          }
  
          loid = list_append_unique_oid(loid, procoid);
          found = true;
      }
  
      ReleaseSysCacheList(catlist);
  
      if (!found)
      {
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_FUNCTION),
                   errmsg("\"%s\" is not a function",
                          (funcname))));
          return NIL;
      }
  
      return loid;
  }
  /*
   * function input func_name is just a normal list whose element is character string.
   */
  List * FunctionGetOidsByNameString(List * func_name)
  {
      char       *schemaname = NULL;
      char       *funcname = NULL;
  
      /* deconstruct the name list */
      StringDeconstructQualifiedName(func_name, &schemaname, &funcname);
  
      return FunctionGetOidsByNameInner(schemaname, funcname);
  }
  #endif
  
  
  /*
   * 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.  (argnames must be NIL, and expand_variadic
   * and expand_defaults must be false, in this case.)
   *
   * If argnames isn't NIL, we are considering a named- or mixed-notation call,
   * and only functions having all the listed argument names will be returned.
   * (We assume that length(argnames) <= nargs and all the passed-in names are
   * distinct.)  The returned structs will include an argnumbers array showing
   * the actual argument index for each logical argument position.
   *
   * If expand_variadic is true, then variadic functions having the same number
   * or fewer arguments will be retrieved, with the variadic argument and any
   * additional argument positions filled with the variadic element type.
   * nvargs in the returned struct is set to the number of such arguments.
   * If expand_variadic is false, variadic arguments are not treated specially,
   * and the returned nvargs will always be zero.
   *
   * If expand_defaults is true, functions that could match after insertion of
   * default argument values will also be retrieved.  In this case the returned
   * structs could have nargs > passed-in nargs, and ndargs is set to the number
   * of additional args (which can be retrieved from the function's
   * proargdefaults entry).
   *
   * It is not possible for nvargs and ndargs to both be nonzero in the same
   * list entry, since default insertion allows matches to functions with more
   * than nargs arguments while the variadic transformation requires the same
   * number or less.
   *
   * When argnames isn't NIL, the returned args[] type arrays are not ordered
   * according to the functions' declarations, but rather according to the call:
   * first any positional arguments, then the named arguments, then defaulted
   * arguments (if needed and allowed by expand_defaults).  The argnumbers[]
   * array can be used to map this back to the catalog information.
   * argnumbers[k] is set to the proargtypes index of the k'th call argument.
   *
   * We search a single namespace if the function name is qualified, else
   * all namespaces in the search path.  In the multiple-namespace case,
   * we arrange for entries in earlier namespaces to mask identical entries in
   * later namespaces.
   *
   * When expanding variadics, we arrange for non-variadic functions to mask
   * variadic ones if the expanded argument list is the same.  It is still
   * possible for there to be conflicts between different variadic functions,
   * however.
   *
   * It is guaranteed that the return list will never contain multiple entries
   * with identical argument lists.  When expand_defaults is true, the entries
   * could have more than nargs positions, but we still guarantee that they are
   * distinct in the first nargs positions.  However, if argnames isn't NIL or
   * either expand_variadic or expand_defaults is true, there might be multiple
   * candidate functions that expand to identical argument lists.  Rather than
   * throw error here, we report such situations by returning a single entry
   * with oid = 0 that represents a set of such conflicting candidates.
   * The caller might end up discarding such an entry anyway, but if it selects
   * such an entry it should react as though the call were ambiguous.
   *
   * If missing_ok is true, an empty list (NULL) is returned if the name was
   * schema- qualified with a schema that does not exist.  Likewise if no
   * candidate is found for other reasons.
   */
  FuncCandidateList
  FuncnameGetCandidates(List *names, int nargs, List *argnames,
                        bool expand_variadic, bool expand_defaults,
                        bool missing_ok)
  {// #lizard forgives
      FuncCandidateList resultList = NULL;
      bool        any_special = false;
      char       *schemaname;
      char       *funcname;
      Oid            namespaceId;
      CatCList   *catlist;
      int            i;
  
      /* check for caller error */
      Assert(nargs >= 0 || !(expand_variadic | expand_defaults));
  
      /* deconstruct the name list */
      DeconstructQualifiedName(names, &schemaname, &funcname);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (!OidIsValid(namespaceId))
              return NULL;
      }
      else
      {
          /* flag to indicate we need namespace search */
          namespaceId = InvalidOid;
          recomputeNamespacePath();
      }
  
      /* Search syscache by name only */
      catlist = SearchSysCacheList1(PROCNAMEARGSNSP, 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            effective_nargs;
          int            pathpos = 0;
          bool        variadic;
          bool        use_defaults;
          Oid            va_elem_type;
          int           *argnumbers = NULL;
          FuncCandidateList newResult;
  
          if (OidIsValid(namespaceId))
          {
              /* Consider only procs in specified namespace */
              if (procform->pronamespace != namespaceId)
                  continue;
          }
          else
          {
              /*
               * Consider only procs that are in the search path and are not in
               * the temp namespace.
               */
              ListCell   *nsp;
  
              foreach(nsp, activeSearchPath)
              {
                  if (procform->pronamespace == lfirst_oid(nsp) &&
                      procform->pronamespace != myTempNamespace)
                      break;
                  pathpos++;
              }
              if (nsp == NULL)
                  continue;        /* proc is not in search path */
          }
  
          if (argnames != NIL)
          {
              /*
               * Call uses named or mixed notation
               *
               * Named or mixed notation can match a variadic function only if
               * expand_variadic is off; otherwise there is no way to match the
               * presumed-nameless parameters expanded from the variadic array.
               */
              if (OidIsValid(procform->provariadic) && expand_variadic)
                  continue;
              va_elem_type = InvalidOid;
              variadic = false;
  
              /*
               * Check argument count.
               */
              Assert(nargs >= 0); /* -1 not supported with argnames */
  
              if (pronargs > nargs && expand_defaults)
              {
                  /* Ignore if not enough default expressions */
                  if (nargs + procform->pronargdefaults < pronargs)
                      continue;
                  use_defaults = true;
              }
              else
                  use_defaults = false;
  
              /* Ignore if it doesn't match requested argument count */
              if (pronargs != nargs && !use_defaults)
                  continue;
  
              /* Check for argument name match, generate positional mapping */
              if (!MatchNamedCall(proctup, nargs, argnames,
                                  &argnumbers))
                  continue;
  
              /* Named argument matching is always "special" */
              any_special = true;
          }
          else
          {
              /*
               * Call uses positional notation
               *
               * Check if function is variadic, and get variadic element type if
               * so.  If expand_variadic is false, we should just ignore
               * variadic-ness.
               */
              if (pronargs <= nargs && expand_variadic)
              {
                  va_elem_type = procform->provariadic;
                  variadic = OidIsValid(va_elem_type);
                  any_special |= variadic;
              }
              else
              {
                  va_elem_type = InvalidOid;
                  variadic = false;
              }
  
              /*
               * Check if function can match by using parameter defaults.
               */
              if (pronargs > nargs && expand_defaults)
              {
                  /* Ignore if not enough default expressions */
                  if (nargs + procform->pronargdefaults < pronargs)
                      continue;
                  use_defaults = true;
                  any_special = true;
              }
              else
                  use_defaults = false;
  
              /* Ignore if it doesn't match requested argument count */
              if (nargs >= 0 && pronargs != nargs && !variadic && !use_defaults)
                  continue;
          }
  
          /*
           * We must compute the effective argument list so that we can easily
           * compare it to earlier results.  We waste a palloc cycle if it gets
           * masked by an earlier result, but really that's a pretty infrequent
           * case so it's not worth worrying about.
           */
          effective_nargs = Max(pronargs, nargs);
          newResult = (FuncCandidateList)
              palloc(offsetof(struct _FuncCandidateList, args) +
                     effective_nargs * sizeof(Oid));
          newResult->pathpos = pathpos;
          newResult->oid = HeapTupleGetOid(proctup);
          newResult->nargs = effective_nargs;
          newResult->argnumbers = argnumbers;
          if (argnumbers)
          {
              /* Re-order the argument types into call's logical order */
              Oid           *proargtypes = procform->proargtypes.values;
              int            i;
  
              for (i = 0; i < pronargs; i++)
                  newResult->args[i] = proargtypes[argnumbers[i]];
          }
          else
          {
              /* Simple positional case, just copy proargtypes as-is */
              memcpy(newResult->args, procform->proargtypes.values,
                     pronargs * sizeof(Oid));
          }
          if (variadic)
          {
              int            i;
  
              newResult->nvargs = effective_nargs - pronargs + 1;
              /* Expand variadic argument into N copies of element type */
              for (i = pronargs - 1; i < effective_nargs; i++)
                  newResult->args[i] = va_elem_type;
          }
          else
              newResult->nvargs = 0;
          newResult->ndargs = use_defaults ? pronargs - nargs : 0;
  
          /*
           * Does it have the same arguments as something we already accepted?
           * If so, decide what to do to avoid returning duplicate argument
           * lists.  We can skip this check for the single-namespace case if no
           * special (named, variadic or defaults) match has been made, since
           * then the unique index on pg_proc guarantees all the matches have
           * different argument lists.
           */
          if (resultList != NULL &&
              (any_special || !OidIsValid(namespaceId)))
          {
              /*
               * If we have an ordered list from SearchSysCacheList (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.  Also, if either the current candidate or any
               * previous candidate is a special match, we can't assume that
               * conflicts are adjacent.
               *
               * We ignore defaulted arguments in deciding what is a match.
               */
              FuncCandidateList prevResult;
  
              if (catlist->ordered && !any_special)
              {
                  /* ndargs must be 0 if !any_special */
                  if (effective_nargs == resultList->nargs &&
                      memcmp(newResult->args,
                             resultList->args,
                             effective_nargs * sizeof(Oid)) == 0)
                      prevResult = resultList;
                  else
                      prevResult = NULL;
              }
              else
              {
                  int            cmp_nargs = newResult->nargs - newResult->ndargs;
  
                  for (prevResult = resultList;
                       prevResult;
                       prevResult = prevResult->next)
                  {
                      if (cmp_nargs == prevResult->nargs - prevResult->ndargs &&
                          memcmp(newResult->args,
                                 prevResult->args,
                                 cmp_nargs * sizeof(Oid)) == 0)
                          break;
                  }
              }
  
              if (prevResult)
              {
                  /*
                   * We have a match with a previous result.  Decide which one
                   * to keep, or mark it ambiguous if we can't decide.  The
                   * logic here is preference > 0 means prefer the old result,
                   * preference < 0 means prefer the new, preference = 0 means
                   * ambiguous.
                   */
                  int            preference;
  
                  if (pathpos != prevResult->pathpos)
                  {
                      /*
                       * Prefer the one that's earlier in the search path.
                       */
                      preference = pathpos - prevResult->pathpos;
                  }
                  else if (variadic && prevResult->nvargs == 0)
                  {
                      /*
                       * With variadic functions we could have, for example,
                       * both foo(numeric) and foo(variadic numeric[]) in the
                       * same namespace; if so we prefer the non-variadic match
                       * on efficiency grounds.
                       */
                      preference = 1;
                  }
                  else if (!variadic && prevResult->nvargs > 0)
                  {
                      preference = -1;
                  }
                  else
                  {
                      /*----------
                       * We can't decide.  This can happen with, for example,
                       * both foo(numeric, variadic numeric[]) and
                       * foo(variadic numeric[]) in the same namespace, or
                       * both foo(int) and foo (int, int default something)
                       * in the same namespace, or both foo(a int, b text)
                       * and foo(b text, a int) in the same namespace.
                       *----------
                       */
                      preference = 0;
                  }
  
                  if (preference > 0)
                  {
                      /* keep previous result */
                      pfree(newResult);
                      continue;
                  }
                  else if (preference < 0)
                  {
                      /* remove previous result from the list */
                      if (prevResult == resultList)
                          resultList = prevResult->next;
                      else
                      {
                          FuncCandidateList prevPrevResult;
  
                          for (prevPrevResult = resultList;
                               prevPrevResult;
                               prevPrevResult = prevPrevResult->next)
                          {
                              if (prevResult == prevPrevResult->next)
                              {
                                  prevPrevResult->next = prevResult->next;
                                  break;
                              }
                          }
                          Assert(prevPrevResult); /* assert we found it */
                      }
                      pfree(prevResult);
                      /* fall through to add newResult to list */
                  }
                  else
                  {
                      /* mark old result as ambiguous, discard new */
                      prevResult->oid = InvalidOid;
                      pfree(newResult);
                      continue;
                  }
              }
          }
  
          /*
           * Okay to add it to result list
           */
          newResult->next = resultList;
          resultList = newResult;
      }
  
      ReleaseSysCacheList(catlist);
  
      return resultList;
  }
  
  /*
   * MatchNamedCall
   *        Given a pg_proc heap tuple and a call's list of argument names,
   *        check whether the function could match the call.
   *
   * The call could match if all supplied argument names are accepted by
   * the function, in positions after the last positional argument, and there
   * are defaults for all unsupplied arguments.
   *
   * The number of positional arguments is nargs - list_length(argnames).
   * Note caller has already done basic checks on argument count.
   *
   * On match, return true and fill *argnumbers with a palloc'd array showing
   * the mapping from call argument positions to actual function argument
   * numbers.  Defaulted arguments are included in this map, at positions
   * after the last supplied argument.
   */
  static bool
  MatchNamedCall(HeapTuple proctup, int nargs, List *argnames,
                 int **argnumbers)
  {// #lizard forgives
      Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(proctup);
      int            pronargs = procform->pronargs;
      int            numposargs = nargs - list_length(argnames);
      int            pronallargs;
      Oid           *p_argtypes;
      char      **p_argnames;
      char       *p_argmodes;
      bool        arggiven[FUNC_MAX_ARGS];
      bool        isnull;
      int            ap;                /* call args position */
      int            pp;                /* proargs position */
      ListCell   *lc;
  
      Assert(argnames != NIL);
      Assert(numposargs >= 0);
      Assert(nargs <= pronargs);
  
      /* Ignore this function if its proargnames is null */
      (void) SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_proargnames,
                             &isnull);
      if (isnull)
          return false;
  
      /* OK, let's extract the argument names and types */
      pronallargs = get_func_arg_info(proctup,
                                      &p_argtypes, &p_argnames, &p_argmodes);
      Assert(p_argnames != NULL);
  
      /* initialize state for matching */
      *argnumbers = (int *) palloc(pronargs * sizeof(int));
      memset(arggiven, false, pronargs * sizeof(bool));
  
      /* there are numposargs positional args before the named args */
      for (ap = 0; ap < numposargs; ap++)
      {
          (*argnumbers)[ap] = ap;
          arggiven[ap] = true;
      }
  
      /* now examine the named args */
      foreach(lc, argnames)
      {
          char       *argname = (char *) lfirst(lc);
          bool        found;
          int            i;
  
          pp = 0;
          found = false;
          for (i = 0; i < pronallargs; i++)
          {
              /* consider only input parameters */
              if (p_argmodes &&
                  (p_argmodes[i] != FUNC_PARAM_IN &&
                   p_argmodes[i] != FUNC_PARAM_INOUT &&
                   p_argmodes[i] != FUNC_PARAM_VARIADIC))
                  continue;
              if (p_argnames[i] && strcmp(p_argnames[i], argname) == 0)
              {
                  /* fail if argname matches a positional argument */
                  if (arggiven[pp])
                      return false;
                  arggiven[pp] = true;
                  (*argnumbers)[ap] = pp;
                  found = true;
                  break;
              }
              /* increase pp only for input parameters */
              pp++;
          }
          /* if name isn't in proargnames, fail */
          if (!found)
              return false;
          ap++;
      }
  
      Assert(ap == nargs);        /* processed all actual parameters */
  
      /* Check for default arguments */
      if (nargs < pronargs)
      {
          int            first_arg_with_default = pronargs - procform->pronargdefaults;
  
          for (pp = numposargs; pp < pronargs; pp++)
          {
              if (arggiven[pp])
                  continue;
              /* fail if arg not given and no default available */
              if (pp < first_arg_with_default)
                  return false;
              (*argnumbers)[ap++] = pp;
          }
      }
  
      Assert(ap == pronargs);        /* processed all function parameters */
  
      return true;
  }
  
  /*
   * 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;
  
      proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
      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(activeSearchPath, 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, NIL, false, false, false);
  
          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;
              }
          }
      }
  
      ReleaseSysCache(proctup);
  
      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.  If the name is schema-qualified and the given
   * schema does not exist, InvalidOid is returned.
   */
  Oid
  OpernameGetOprid(List *names, Oid oprleft, Oid oprright)
  {// #lizard forgives
      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;
  
          namespaceId = LookupExplicitNamespace(schemaname, true);
          if (OidIsValid(namespaceId))
          {
              HeapTuple    opertup;
  
              opertup = SearchSysCache4(OPERNAMENSP,
                                        CStringGetDatum(opername),
                                        ObjectIdGetDatum(oprleft),
                                        ObjectIdGetDatum(oprright),
                                        ObjectIdGetDatum(namespaceId));
              if (HeapTupleIsValid(opertup))
              {
                  Oid            result = HeapTupleGetOid(opertup);
  
                  ReleaseSysCache(opertup);
                  return result;
              }
          }
  
          return InvalidOid;
      }
  
      /* Search syscache by name and argument types */
      catlist = SearchSysCacheList3(OPERNAMENSP,
                                    CStringGetDatum(opername),
                                    ObjectIdGetDatum(oprleft),
                                    ObjectIdGetDatum(oprright));
  
      if (catlist->n_members == 0)
      {
          /* no hope, fall out early */
          ReleaseSysCacheList(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, activeSearchPath)
      {
          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);
  
                  ReleaseSysCacheList(catlist);
                  return result;
              }
          }
      }
  
      ReleaseSysCacheList(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, bool missing_schema_ok)
  {// #lizard forgives
      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, missing_schema_ok);
          if (missing_schema_ok && !OidIsValid(namespaceId))
              return NULL;
      }
      else
      {
          /* flag to indicate we need namespace search */
          namespaceId = InvalidOid;
          recomputeNamespacePath();
      }
  
      /* Search syscache by name only */
      catlist = SearchSysCacheList1(OPERNAMENSP, 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(offsetof(struct _FuncCandidateList, args) + \
                                2 * 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, activeSearchPath)
              {
                  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 SearchSysCacheList (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->nvargs = 0;
          newResult->ndargs = 0;
          newResult->argnumbers = NULL;
          newResult->args[0] = operform->oprleft;
          newResult->args[1] = operform->oprright;
          newResult->next = resultList;
          resultList = newResult;
      }
  
      ReleaseSysCacheList(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;
  
      oprtup = SearchSysCache1(OPEROID, ObjectIdGetDatum(oprid));
      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(activeSearchPath, 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);
      }
  
      ReleaseSysCache(oprtup);
  
      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, activeSearchPath)
      {
          Oid            namespaceId = lfirst_oid(l);
  
          if (namespaceId == myTempNamespace)
              continue;            /* do not look in temp namespace */
  
          opcid = GetSysCacheOid3(CLAAMNAMENSP,
                                  ObjectIdGetDatum(amid),
                                  PointerGetDatum(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;
  
      opctup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opcid));
      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(activeSearchPath, 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->opcmethod, opcname) == opcid);
      }
  
      ReleaseSysCache(opctup);
  
      return visible;
  }
  
  /*
   * OpfamilynameGetOpfid
   *        Try to resolve an unqualified index opfamily name.
   *        Returns OID if opfamily 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
  OpfamilynameGetOpfid(Oid amid, const char *opfname)
  {
      Oid            opfid;
      ListCell   *l;
  
      recomputeNamespacePath();
  
      foreach(l, activeSearchPath)
      {
          Oid            namespaceId = lfirst_oid(l);
  
          if (namespaceId == myTempNamespace)
              continue;            /* do not look in temp namespace */
  
          opfid = GetSysCacheOid3(OPFAMILYAMNAMENSP,
                                  ObjectIdGetDatum(amid),
                                  PointerGetDatum(opfname),
                                  ObjectIdGetDatum(namespaceId));
          if (OidIsValid(opfid))
              return opfid;
      }
  
      /* Not found in path */
      return InvalidOid;
  }
  
  /*
   * OpfamilyIsVisible
   *        Determine whether an opfamily (identified by OID) is visible in the
   *        current search path.  Visible means "would be found by searching
   *        for the unqualified opfamily name".
   */
  bool
  OpfamilyIsVisible(Oid opfid)
  {
      HeapTuple    opftup;
      Form_pg_opfamily opfform;
      Oid            opfnamespace;
      bool        visible;
  
      opftup = SearchSysCache1(OPFAMILYOID, ObjectIdGetDatum(opfid));
      if (!HeapTupleIsValid(opftup))
          elog(ERROR, "cache lookup failed for opfamily %u", opfid);
      opfform = (Form_pg_opfamily) GETSTRUCT(opftup);
  
      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.
       */
      opfnamespace = opfform->opfnamespace;
      if (opfnamespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, opfnamespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another opfamily of the same name earlier in the path. So
           * we must do a slow check to see if this opfamily would be found by
           * OpfamilynameGetOpfid.
           */
          char       *opfname = NameStr(opfform->opfname);
  
          visible = (OpfamilynameGetOpfid(opfform->opfmethod, opfname) == opfid);
      }
  
      ReleaseSysCache(opftup);
  
      return visible;
  }
  
  /*
   * lookup_collation
   *        If there's a collation of the given name/namespace, and it works
   *        with the given encoding, return its OID.  Else return InvalidOid.
   */
  static Oid
  lookup_collation(const char *collname, Oid collnamespace, int32 encoding)
  {
      Oid            collid;
      HeapTuple    colltup;
      Form_pg_collation collform;
  
      /* Check for encoding-specific entry (exact match) */
      collid = GetSysCacheOid3(COLLNAMEENCNSP,
                               PointerGetDatum(collname),
                               Int32GetDatum(encoding),
                               ObjectIdGetDatum(collnamespace));
      if (OidIsValid(collid))
          return collid;
  
      /*
       * Check for any-encoding entry.  This takes a bit more work: while libc
       * collations with collencoding = -1 do work with all encodings, ICU
       * collations only work with certain encodings, so we have to check that
       * aspect before deciding it's a match.
       */
      colltup = SearchSysCache3(COLLNAMEENCNSP,
                                PointerGetDatum(collname),
                                Int32GetDatum(-1),
                                ObjectIdGetDatum(collnamespace));
      if (!HeapTupleIsValid(colltup))
          return InvalidOid;
      collform = (Form_pg_collation) GETSTRUCT(colltup);
      if (collform->collprovider == COLLPROVIDER_ICU)
      {
          if (is_encoding_supported_by_icu(encoding))
              collid = HeapTupleGetOid(colltup);
          else
              collid = InvalidOid;
      }
      else
      {
          collid = HeapTupleGetOid(colltup);
      }
      ReleaseSysCache(colltup);
      return collid;
  }
  
  /*
   * CollationGetCollid
   *        Try to resolve an unqualified collation name.
   *        Returns OID if collation found in search path, else InvalidOid.
   *
   * Note that this will only find collations that work with the current
   * database's encoding.
   */
  Oid
  CollationGetCollid(const char *collname)
  {
      int32        dbencoding = GetDatabaseEncoding();
      ListCell   *l;
  
      recomputeNamespacePath();
  
      foreach(l, activeSearchPath)
      {
          Oid            namespaceId = lfirst_oid(l);
          Oid            collid;
  
          if (namespaceId == myTempNamespace)
              continue;            /* do not look in temp namespace */
  
          collid = lookup_collation(collname, namespaceId, dbencoding);
          if (OidIsValid(collid))
              return collid;
      }
  
      /* Not found in path */
      return InvalidOid;
  }
  
  /*
   * CollationIsVisible
   *        Determine whether a collation (identified by OID) is visible in the
   *        current search path.  Visible means "would be found by searching
   *        for the unqualified collation name".
   *
   * Note that only collations that work with the current database's encoding
   * will be considered visible.
   */
  bool
  CollationIsVisible(Oid collid)
  {
      HeapTuple    colltup;
      Form_pg_collation collform;
      Oid            collnamespace;
      bool        visible;
  
      colltup = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
      if (!HeapTupleIsValid(colltup))
          elog(ERROR, "cache lookup failed for collation %u", collid);
      collform = (Form_pg_collation) GETSTRUCT(colltup);
  
      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.
       */
      collnamespace = collform->collnamespace;
      if (collnamespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, collnamespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another collation of the same name earlier in the path,
           * or it might not work with the current DB encoding.  So we must do a
           * slow check to see if this collation would be found by
           * CollationGetCollid.
           */
          char       *collname = NameStr(collform->collname);
  
          visible = (CollationGetCollid(collname) == collid);
      }
  
      ReleaseSysCache(colltup);
  
      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, activeSearchPath)
      {
          Oid            namespaceId = lfirst_oid(l);
  
          if (namespaceId == myTempNamespace)
              continue;            /* do not look in temp namespace */
  
          conid = GetSysCacheOid2(CONNAMENSP,
                                  PointerGetDatum(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;
  
      contup = SearchSysCache1(CONVOID, ObjectIdGetDatum(conid));
      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(activeSearchPath, 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);
      }
  
      ReleaseSysCache(contup);
  
      return visible;
  }
  
  /*
   * get_statistics_object_oid - find a statistics object by possibly qualified name
   *
   * If not found, returns InvalidOid if missing_ok, else throws error
   */
  Oid
  get_statistics_object_oid(List *names, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *stats_name;
      Oid            namespaceId;
      Oid            stats_oid = InvalidOid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(names, &schemaname, &stats_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              stats_oid = InvalidOid;
          else
              stats_oid = GetSysCacheOid2(STATEXTNAMENSP,
                                          PointerGetDatum(stats_name),
                                          ObjectIdGetDatum(namespaceId));
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
              stats_oid = GetSysCacheOid2(STATEXTNAMENSP,
                                          PointerGetDatum(stats_name),
                                          ObjectIdGetDatum(namespaceId));
              if (OidIsValid(stats_oid))
                  break;
          }
      }
  
      if (!OidIsValid(stats_oid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("statistics object \"%s\" does not exist",
                          NameListToString(names))));
  
      return stats_oid;
  }
  
  /*
   * StatisticsObjIsVisible
   *        Determine whether a statistics object (identified by OID) is visible in
   *        the current search path.  Visible means "would be found by searching
   *        for the unqualified statistics object name".
   */
  bool
  StatisticsObjIsVisible(Oid relid)
  {
      HeapTuple    stxtup;
      Form_pg_statistic_ext stxform;
      Oid            stxnamespace;
      bool        visible;
  
      stxtup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(relid));
      if (!HeapTupleIsValid(stxtup))
          elog(ERROR, "cache lookup failed for statistics object %u", relid);
      stxform = (Form_pg_statistic_ext) GETSTRUCT(stxtup);
  
      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.
       */
      stxnamespace = stxform->stxnamespace;
      if (stxnamespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, stxnamespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another statistics object of the same name earlier in the
           * path. So we must do a slow check for conflicting objects.
           */
          char       *stxname = NameStr(stxform->stxname);
          ListCell   *l;
  
          visible = false;
          foreach(l, activeSearchPath)
          {
              Oid            namespaceId = lfirst_oid(l);
  
              if (namespaceId == stxnamespace)
              {
                  /* Found it first in path */
                  visible = true;
                  break;
              }
              if (SearchSysCacheExists2(STATEXTNAMENSP,
                                        PointerGetDatum(stxname),
                                        ObjectIdGetDatum(namespaceId)))
              {
                  /* Found something else first in path */
                  break;
              }
          }
      }
  
      ReleaseSysCache(stxtup);
  
      return visible;
  }
  
  /*
   * get_ts_parser_oid - find a TS parser by possibly qualified name
   *
   * If not found, returns InvalidOid if missing_ok, else throws error
   */
  Oid
  get_ts_parser_oid(List *names, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *parser_name;
      Oid            namespaceId;
      Oid            prsoid = InvalidOid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(names, &schemaname, &parser_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              prsoid = InvalidOid;
          else
              prsoid = GetSysCacheOid2(TSPARSERNAMENSP,
                                       PointerGetDatum(parser_name),
                                       ObjectIdGetDatum(namespaceId));
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              prsoid = GetSysCacheOid2(TSPARSERNAMENSP,
                                       PointerGetDatum(parser_name),
                                       ObjectIdGetDatum(namespaceId));
              if (OidIsValid(prsoid))
                  break;
          }
      }
  
      if (!OidIsValid(prsoid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("text search parser \"%s\" does not exist",
                          NameListToString(names))));
  
      return prsoid;
  }
  
  /*
   * TSParserIsVisible
   *        Determine whether a parser (identified by OID) is visible in the
   *        current search path.  Visible means "would be found by searching
   *        for the unqualified parser name".
   */
  bool
  TSParserIsVisible(Oid prsId)
  {
      HeapTuple    tup;
      Form_pg_ts_parser form;
      Oid            namespace;
      bool        visible;
  
      tup = SearchSysCache1(TSPARSEROID, ObjectIdGetDatum(prsId));
      if (!HeapTupleIsValid(tup))
          elog(ERROR, "cache lookup failed for text search parser %u", prsId);
      form = (Form_pg_ts_parser) GETSTRUCT(tup);
  
      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.
       */
      namespace = form->prsnamespace;
      if (namespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, namespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another parser of the same name earlier in the path. So
           * we must do a slow check for conflicting parsers.
           */
          char       *name = NameStr(form->prsname);
          ListCell   *l;
  
          visible = false;
          foreach(l, activeSearchPath)
          {
              Oid            namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              if (namespaceId == namespace)
              {
                  /* Found it first in path */
                  visible = true;
                  break;
              }
              if (SearchSysCacheExists2(TSPARSERNAMENSP,
                                        PointerGetDatum(name),
                                        ObjectIdGetDatum(namespaceId)))
              {
                  /* Found something else first in path */
                  break;
              }
          }
      }
  
      ReleaseSysCache(tup);
  
      return visible;
  }
  
  /*
   * get_ts_dict_oid - find a TS dictionary by possibly qualified name
   *
   * If not found, returns InvalidOid if failOK, else throws error
   */
  Oid
  get_ts_dict_oid(List *names, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *dict_name;
      Oid            namespaceId;
      Oid            dictoid = InvalidOid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(names, &schemaname, &dict_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              dictoid = InvalidOid;
          else
              dictoid = GetSysCacheOid2(TSDICTNAMENSP,
                                        PointerGetDatum(dict_name),
                                        ObjectIdGetDatum(namespaceId));
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              dictoid = GetSysCacheOid2(TSDICTNAMENSP,
                                        PointerGetDatum(dict_name),
                                        ObjectIdGetDatum(namespaceId));
              if (OidIsValid(dictoid))
                  break;
          }
      }
  
      if (!OidIsValid(dictoid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("text search dictionary \"%s\" does not exist",
                          NameListToString(names))));
  
      return dictoid;
  }
  
  /*
   * TSDictionaryIsVisible
   *        Determine whether a dictionary (identified by OID) is visible in the
   *        current search path.  Visible means "would be found by searching
   *        for the unqualified dictionary name".
   */
  bool
  TSDictionaryIsVisible(Oid dictId)
  {
      HeapTuple    tup;
      Form_pg_ts_dict form;
      Oid            namespace;
      bool        visible;
  
      tup = SearchSysCache1(TSDICTOID, ObjectIdGetDatum(dictId));
      if (!HeapTupleIsValid(tup))
          elog(ERROR, "cache lookup failed for text search dictionary %u",
               dictId);
      form = (Form_pg_ts_dict) GETSTRUCT(tup);
  
      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.
       */
      namespace = form->dictnamespace;
      if (namespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, namespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another dictionary of the same name earlier in the path.
           * So we must do a slow check for conflicting dictionaries.
           */
          char       *name = NameStr(form->dictname);
          ListCell   *l;
  
          visible = false;
          foreach(l, activeSearchPath)
          {
              Oid            namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              if (namespaceId == namespace)
              {
                  /* Found it first in path */
                  visible = true;
                  break;
              }
              if (SearchSysCacheExists2(TSDICTNAMENSP,
                                        PointerGetDatum(name),
                                        ObjectIdGetDatum(namespaceId)))
              {
                  /* Found something else first in path */
                  break;
              }
          }
      }
  
      ReleaseSysCache(tup);
  
      return visible;
  }
  
  /*
   * get_ts_template_oid - find a TS template by possibly qualified name
   *
   * If not found, returns InvalidOid if missing_ok, else throws error
   */
  Oid
  get_ts_template_oid(List *names, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *template_name;
      Oid            namespaceId;
      Oid            tmploid = InvalidOid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(names, &schemaname, &template_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              tmploid = InvalidOid;
          else
              tmploid = GetSysCacheOid2(TSTEMPLATENAMENSP,
                                        PointerGetDatum(template_name),
                                        ObjectIdGetDatum(namespaceId));
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              tmploid = GetSysCacheOid2(TSTEMPLATENAMENSP,
                                        PointerGetDatum(template_name),
                                        ObjectIdGetDatum(namespaceId));
              if (OidIsValid(tmploid))
                  break;
          }
      }
  
      if (!OidIsValid(tmploid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("text search template \"%s\" does not exist",
                          NameListToString(names))));
  
      return tmploid;
  }
  
  /*
   * TSTemplateIsVisible
   *        Determine whether a template (identified by OID) is visible in the
   *        current search path.  Visible means "would be found by searching
   *        for the unqualified template name".
   */
  bool
  TSTemplateIsVisible(Oid tmplId)
  {
      HeapTuple    tup;
      Form_pg_ts_template form;
      Oid            namespace;
      bool        visible;
  
      tup = SearchSysCache1(TSTEMPLATEOID, ObjectIdGetDatum(tmplId));
      if (!HeapTupleIsValid(tup))
          elog(ERROR, "cache lookup failed for text search template %u", tmplId);
      form = (Form_pg_ts_template) GETSTRUCT(tup);
  
      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.
       */
      namespace = form->tmplnamespace;
      if (namespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, namespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another template of the same name earlier in the path. So
           * we must do a slow check for conflicting templates.
           */
          char       *name = NameStr(form->tmplname);
          ListCell   *l;
  
          visible = false;
          foreach(l, activeSearchPath)
          {
              Oid            namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              if (namespaceId == namespace)
              {
                  /* Found it first in path */
                  visible = true;
                  break;
              }
              if (SearchSysCacheExists2(TSTEMPLATENAMENSP,
                                        PointerGetDatum(name),
                                        ObjectIdGetDatum(namespaceId)))
              {
                  /* Found something else first in path */
                  break;
              }
          }
      }
  
      ReleaseSysCache(tup);
  
      return visible;
  }
  
  /*
   * get_ts_config_oid - find a TS config by possibly qualified name
   *
   * If not found, returns InvalidOid if missing_ok, else throws error
   */
  Oid
  get_ts_config_oid(List *names, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *config_name;
      Oid            namespaceId;
      Oid            cfgoid = InvalidOid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(names, &schemaname, &config_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              cfgoid = InvalidOid;
          else
              cfgoid = GetSysCacheOid2(TSCONFIGNAMENSP,
                                       PointerGetDatum(config_name),
                                       ObjectIdGetDatum(namespaceId));
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              cfgoid = GetSysCacheOid2(TSCONFIGNAMENSP,
                                       PointerGetDatum(config_name),
                                       ObjectIdGetDatum(namespaceId));
              if (OidIsValid(cfgoid))
                  break;
          }
      }
  
      if (!OidIsValid(cfgoid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("text search configuration \"%s\" does not exist",
                          NameListToString(names))));
  
      return cfgoid;
  }
  
  /*
   * TSConfigIsVisible
   *        Determine whether a text search configuration (identified by OID)
   *        is visible in the current search path.  Visible means "would be found
   *        by searching for the unqualified text search configuration name".
   */
  bool
  TSConfigIsVisible(Oid cfgid)
  {
      HeapTuple    tup;
      Form_pg_ts_config form;
      Oid            namespace;
      bool        visible;
  
      tup = SearchSysCache1(TSCONFIGOID, ObjectIdGetDatum(cfgid));
      if (!HeapTupleIsValid(tup))
          elog(ERROR, "cache lookup failed for text search configuration %u",
               cfgid);
      form = (Form_pg_ts_config) GETSTRUCT(tup);
  
      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.
       */
      namespace = form->cfgnamespace;
      if (namespace != PG_CATALOG_NAMESPACE &&
          !list_member_oid(activeSearchPath, namespace))
          visible = false;
      else
      {
          /*
           * If it is in the path, it might still not be visible; it could be
           * hidden by another configuration of the same name earlier in the
           * path. So we must do a slow check for conflicting configurations.
           */
          char       *name = NameStr(form->cfgname);
          ListCell   *l;
  
          visible = false;
          foreach(l, activeSearchPath)
          {
              Oid            namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              if (namespaceId == namespace)
              {
                  /* Found it first in path */
                  visible = true;
                  break;
              }
              if (SearchSysCacheExists2(TSCONFIGNAMENSP,
                                        PointerGetDatum(name),
                                        ObjectIdGetDatum(namespaceId)))
              {
                  /* Found something else first in path */
                  break;
              }
          }
      }
  
      ReleaseSysCache(tup);
  
      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;
  }
  
  #ifdef _MLS_
  static void StringDeconstructQualifiedName(List *names,
                           char **nspname_p,
                           char **objname_p)
  {
      char       *catalogname;
      char       *schemaname = NULL;
      char       *objname = NULL;
  
      switch (list_length(names))
      {
          case 1:
              objname = (linitial(names));
              break;
          case 2:
              schemaname = (linitial(names));
              objname = (lsecond(names));
              break;
          case 3:
              catalogname = (linitial(names));
              schemaname = (lsecond(names));
              objname = (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;
  }
  
  #endif
  
  /*
   * LookupNamespaceNoError
   *        Look up a schema name.
   *
   * Returns the namespace OID, or InvalidOid if not found.
   *
   * Note this does NOT perform any permissions check --- callers are
   * responsible for being sure that an appropriate check is made.
   * In the majority of cases LookupExplicitNamespace is preferable.
   */
  Oid
  LookupNamespaceNoError(const char *nspname)
  {
      /* check for pg_temp alias */
      if (strcmp(nspname, "pg_temp") == 0)
      {
          if (OidIsValid(myTempNamespace))
          {
              InvokeNamespaceSearchHook(myTempNamespace, true);
              return myTempNamespace;
          }
  #ifdef XCP
          /*
           * Try to find temporary namespace created by other backend of
           * the same distributed session. If not found myTempNamespace will
           * be InvalidOid, that is correct result.
           */
          FindTemporaryNamespace();
          return myTempNamespace;
  #else
          /*
           * 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 report "not found".
           */
          return InvalidOid;
  #endif
      }
  
      return get_namespace_oid(nspname, true);
  }
  
  /*
   * LookupExplicitNamespace
   *        Process an explicitly-specified schema name: look up the schema
   *        and verify we have USAGE (lookup) rights in it.
   *
   * Returns the namespace OID
   */
  Oid
  LookupExplicitNamespace(const char *nspname, bool missing_ok)
  {// #lizard forgives
      Oid            namespaceId;
      AclResult    aclresult;
  
      /* check for pg_temp alias */
      if (strcmp(nspname, "pg_temp") == 0)
      {
          if (OidIsValid(myTempNamespace))
              return myTempNamespace;
  
  #ifdef XCP
          /*
           * Try to find temporary namespace created by other backend of
           * the same distributed session.
           */
          FindTemporaryNamespace();
          if (OidIsValid(myTempNamespace))
              return myTempNamespace;
  #endif
  
          /*
           * 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.
           */
      }
  
      namespaceId = get_namespace_oid(nspname, missing_ok);
      if (missing_ok && !OidIsValid(namespaceId))
          return InvalidOid;
  
      aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_USAGE);
      if (aclresult != ACLCHECK_OK)
          aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
                         nspname);
      /* Schema search hook for this lookup */
      InvokeNamespaceSearchHook(namespaceId, true);
  
      return namespaceId;
  }
  
  /*
   * LookupCreationNamespace
   *        Look up the schema and verify we have CREATE rights on it.
   *
   * This is just like LookupExplicitNamespace except for the different
   * 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 (!OidIsValid(myTempNamespace))
              InitTempTableNamespace();
          return myTempNamespace;
      }
  
      namespaceId = get_namespace_oid(nspname, false);
  
      aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
      if (aclresult != ACLCHECK_OK)
          aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
                         nspname);
  
      return namespaceId;
  }
  
  /*
   * Common checks on switching namespaces.
   *
   * We complain if either the old or new namespaces is a temporary schema
   * (or temporary toast schema), or if either the old or new namespaces is the
   * TOAST schema.
   */
  void
  CheckSetNamespace(Oid oldNspOid, Oid nspOid)
  {
      /* disallow renaming into or out of temp schemas */
      if (isAnyTempNamespace(nspOid) || isAnyTempNamespace(oldNspOid))
          ereport(ERROR,
                  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                   errmsg("cannot move objects into or out of temporary schemas")));
  
      /* same for TOAST schema */
      if (nspOid == PG_TOAST_NAMESPACE || oldNspOid == PG_TOAST_NAMESPACE)
          ereport(ERROR,
                  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                   errmsg("cannot move objects into or out of TOAST schema")));
  }
  
  /*
   * 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 (!OidIsValid(myTempNamespace))
                  InitTempTableNamespace();
              return myTempNamespace;
          }
          /* use exact schema given */
          namespaceId = get_namespace_oid(schemaname, false);
          /* we do not check for USAGE rights here! */
      }
      else
      {
          /* use the default creation namespace */
          recomputeNamespacePath();
          if (activeTempCreationPending)
          {
              /* Need to initialize temp namespace */
              InitTempTableNamespace();
              return myTempNamespace;
          }
          namespaceId = activeCreationNamespace;
          if (!OidIsValid(namespaceId))
              ereport(ERROR,
                      (errcode(ERRCODE_UNDEFINED_SCHEMA),
                       errmsg("no schema has been selected to create in")));
      }
  
      return namespaceId;
  }
  
  /*
   * get_namespace_oid - given a namespace name, look up the OID
   *
   * If missing_ok is false, throw an error if namespace name not found.  If
   * true, just return InvalidOid.
   */
  Oid
  get_namespace_oid(const char *nspname, bool missing_ok)
  {
      Oid            oid;
  
      oid = GetSysCacheOid1(NAMESPACENAME, CStringGetDatum(nspname));
      if (!OidIsValid(oid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_SCHEMA),
                   errmsg("schema \"%s\" does not exist", nspname)));
  
      return oid;
  }
  
  /*
   * makeRangeVarFromNameList
   *        Utility routine to convert a qualified-name list into RangeVar form.
   */
  RangeVar *
  makeRangeVarFromNameList(List *names)
  {
      RangeVar   *rel = makeRangeVar(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.
   *
   * In most scenarios the list elements should always be Value strings,
   * but we also allow A_Star for the convenience of ColumnRef processing.
   */
  char *
  NameListToString(List *names)
  {
      StringInfoData string;
      ListCell   *l;
  
      initStringInfo(&string);
  
      foreach(l, names)
      {
          Node       *name = (Node *) lfirst(l);
  
          if (l != list_head(names))
              appendStringInfoChar(&string, '.');
  
          if (IsA(name, String))
              appendStringInfoString(&string, strVal(name));
          else if (IsA(name, A_Star))
              appendStringInfoChar(&string, '*');
          else
              elog(ERROR, "unexpected node type in name list: %d",
                   (int) nodeTag(name));
      }
  
      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)
  {
      if (OidIsValid(myTempNamespace) && myTempNamespace == namespaceId)
          return true;
      return false;
  }
  
  /*
   * isTempToastNamespace - is the given namespace my temporary-toast-table
   *        namespace?
   */
  bool
  isTempToastNamespace(Oid namespaceId)
  {
      if (OidIsValid(myTempToastNamespace) && myTempToastNamespace == namespaceId)
          return true;
      return false;
  }
  
  /*
   * isTempOrTempToastNamespace - is the given namespace my temporary-table
   *        namespace or my temporary-toast-table namespace?
   */
  bool
  isTempOrTempToastNamespace(Oid namespaceId)
  {
      if (OidIsValid(myTempNamespace) &&
          (myTempNamespace == namespaceId || myTempToastNamespace == namespaceId))
          return true;
      return false;
  }
  
  /*
   * isAnyTempNamespace - is the given namespace a temporary-table namespace
   * (either my own, or another backend's)?  Temporary-toast-table namespaces
   * are included, too.
   */
  bool
  isAnyTempNamespace(Oid namespaceId)
  {
      bool        result;
      char       *nspname;
  
      /* True if the namespace name starts with "pg_temp_" or "pg_toast_temp_" */
      nspname = get_namespace_name(namespaceId);
      if (!nspname)
          return false;            /* no such namespace? */
      result = (strncmp(nspname, "pg_temp_", 8) == 0) ||
          (strncmp(nspname, "pg_toast_temp_", 14) == 0);
      pfree(nspname);
      return result;
  }
  
  /*
   * isOtherTempNamespace - is the given namespace some other backend's
   * temporary-table namespace (including temporary-toast-table namespaces)?
   *
   * Note: for most purposes in the C code, this function is obsolete.  Use
   * RELATION_IS_OTHER_TEMP() instead to detect non-local temp relations.
   */
  bool
  isOtherTempNamespace(Oid namespaceId)
  {
      /* If it's my own temp namespace, say "false" */
      if (isTempOrTempToastNamespace(namespaceId))
          return false;
      /* Else, if it's any temp namespace, say "true" */
      return isAnyTempNamespace(namespaceId);
  }
  
  /*
   * GetTempNamespaceBackendId - if the given namespace is a temporary-table
   * namespace (either my own, or another backend's), return the BackendId
   * that owns it.  Temporary-toast-table namespaces are included, too.
   * If it isn't a temp namespace, return InvalidBackendId.
   */
  int
  GetTempNamespaceBackendId(Oid namespaceId)
  {
      int            result;
      char       *nspname;
  
      /* See if the namespace name starts with "pg_temp_" or "pg_toast_temp_" */
      nspname = get_namespace_name(namespaceId);
      if (!nspname)
          return InvalidBackendId;    /* no such namespace? */
      if (strncmp(nspname, "pg_temp_", 8) == 0)
          result = atoi(nspname + 8);
      else if (strncmp(nspname, "pg_toast_temp_", 14) == 0)
          result = atoi(nspname + 14);
      else
          result = InvalidBackendId;
      pfree(nspname);
      return result;
  }
  
  /*
   * GetTempToastNamespace - get the OID of my temporary-toast-table namespace,
   * which must already be assigned.  (This is only used when creating a toast
   * table for a temp table, so we must have already done InitTempTableNamespace)
   */
  Oid
  GetTempToastNamespace(void)
  {
      Assert(OidIsValid(myTempToastNamespace));
      return myTempToastNamespace;
  }
  
  
  /*
   * GetTempNamespaceState - fetch status of session's temporary namespace
   *
   * This is used for conveying state to a parallel worker, and is not meant
   * for general-purpose access.
   */
  void
  GetTempNamespaceState(Oid *tempNamespaceId, Oid *tempToastNamespaceId)
  {
      /* Return namespace OIDs, or 0 if session has not created temp namespace */
      *tempNamespaceId = myTempNamespace;
      *tempToastNamespaceId = myTempToastNamespace;
  }
  
  /*
   * SetTempNamespaceState - set status of session's temporary namespace
   *
   * This is used for conveying state to a parallel worker, and is not meant for
   * general-purpose access.  By transferring these namespace OIDs to workers,
   * we ensure they will have the same notion of the search path as their leader
   * does.
   */
  void
  SetTempNamespaceState(Oid tempNamespaceId, Oid tempToastNamespaceId)
  {
      /* Worker should not have created its own namespaces ... */
      Assert(myTempNamespace == InvalidOid);
      Assert(myTempToastNamespace == InvalidOid);
      Assert(myTempNamespaceSubID == InvalidSubTransactionId);
  
      /* Assign same namespace OIDs that leader has */
      myTempNamespace = tempNamespaceId;
      myTempToastNamespace = tempToastNamespaceId;
  
      /*
       * It's fine to leave myTempNamespaceSubID == InvalidSubTransactionId.
       * Even if the namespace is new so far as the leader is concerned, it's
       * not new to the worker, and we certainly wouldn't want the worker trying
       * to destroy it.
       */
  
      baseSearchPathValid = false;    /* may need to rebuild list */
  }
  
  
  /*
   * GetOverrideSearchPath - fetch current search path definition in form
   * used by PushOverrideSearchPath.
   *
   * The result structure is allocated in the specified memory context
   * (which might or might not be equal to CurrentMemoryContext); but any
   * junk created by revalidation calculations will be in CurrentMemoryContext.
   */
  OverrideSearchPath *
  GetOverrideSearchPath(MemoryContext context)
  {
      OverrideSearchPath *result;
      List       *schemas;
      MemoryContext oldcxt;
  
      recomputeNamespacePath();
  
      oldcxt = MemoryContextSwitchTo(context);
  
      result = (OverrideSearchPath *) palloc0(sizeof(OverrideSearchPath));
      schemas = list_copy(activeSearchPath);
      while (schemas && linitial_oid(schemas) != activeCreationNamespace)
      {
          if (linitial_oid(schemas) == myTempNamespace)
              result->addTemp = true;
          else
          {
  #ifdef _PG_ORCL_
              Assert(IsSystemNamespace(linitial_oid(schemas)));
  #else
              Assert(linitial_oid(schemas) == PG_CATALOG_NAMESPACE);
  #endif
              result->addCatalog = true;
          }
          schemas = list_delete_first(schemas);
      }
      result->schemas = schemas;
  
      MemoryContextSwitchTo(oldcxt);
  
      return result;
  }
  
  /*
   * CopyOverrideSearchPath - copy the specified OverrideSearchPath.
   *
   * The result structure is allocated in CurrentMemoryContext.
   */
  OverrideSearchPath *
  CopyOverrideSearchPath(OverrideSearchPath *path)
  {
      OverrideSearchPath *result;
  
      result = (OverrideSearchPath *) palloc(sizeof(OverrideSearchPath));
      result->schemas = list_copy(path->schemas);
      result->addCatalog = path->addCatalog;
      result->addTemp = path->addTemp;
  
      return result;
  }
  
  /*
   * OverrideSearchPathMatchesCurrent - does path match current setting?
   */
  bool
  OverrideSearchPathMatchesCurrent(OverrideSearchPath *path)
  {// #lizard forgives
      ListCell   *lc,
                 *lcp;
  
      recomputeNamespacePath();
  
      /* We scan down the activeSearchPath to see if it matches the input. */
      lc = list_head(activeSearchPath);
  
      /* If path->addTemp, first item should be my temp namespace. */
      if (path->addTemp)
      {
          if (lc && lfirst_oid(lc) == myTempNamespace)
              lc = lnext(lc);
          else
              return false;
      }
  
      /* If path->addCatalog, next item should be pg_catalog. */
      if (path->addCatalog)
      {
  #ifdef _PG_ORCL_
          if (lc && IsSystemNamespace(lfirst_oid(lc)))
  #else
          if (lc && lfirst_oid(lc) == PG_CATALOG_NAMESPACE)
  #endif
              lc = lnext(lc);
          else
              return false;
      }
      /* We should now be looking at the activeCreationNamespace. */
      if (activeCreationNamespace != (lc ? lfirst_oid(lc) : InvalidOid))
          return false;
      /* The remainder of activeSearchPath should match path->schemas. */
      foreach(lcp, path->schemas)
      {
          if (lc && lfirst_oid(lc) == lfirst_oid(lcp))
              lc = lnext(lc);
          else
              return false;
      }
      if (lc)
          return false;
      return true;
  }
  
  /*
   * PushOverrideSearchPath - temporarily override the search path
   *
   * We allow nested overrides, hence the push/pop terminology.  The GUC
   * search_path variable is ignored while an override is active.
   *
   * It's possible that newpath->useTemp is set but there is no longer any
   * active temp namespace, if the path was saved during a transaction that
   * created a temp namespace and was later rolled back.  In that case we just
   * ignore useTemp.  A plausible alternative would be to create a new temp
   * namespace, but for existing callers that's not necessary because an empty
   * temp namespace wouldn't affect their results anyway.
   *
   * It's also worth noting that other schemas listed in newpath might not
   * exist anymore either.  We don't worry about this because OIDs that match
   * no existing namespace will simply not produce any hits during searches.
   */
  void
  PushOverrideSearchPath(OverrideSearchPath *newpath)
  {
      OverrideStackEntry *entry;
      List       *oidlist;
      Oid            firstNS;
      MemoryContext oldcxt;
  
      /*
       * Copy the list for safekeeping, and insert implicitly-searched
       * namespaces as needed.  This code should track recomputeNamespacePath.
       */
      oldcxt = MemoryContextSwitchTo(TopMemoryContext);
  
      oidlist = list_copy(newpath->schemas);
  
      /*
       * Remember the first member of the explicit list.
       */
      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 (newpath->addCatalog)
      {
  #ifdef _PG_ORCL_
          if (support_oracle_compatible && !list_member_oid(oidlist, PG_ORACLE_NAMESPACE))
              oidlist = lappend_oid(oidlist, PG_ORACLE_NAMESPACE); // lcons_oid(PG_ORACLE_NAMESPACE, oidlist);
  #endif
          oidlist = lcons_oid(PG_CATALOG_NAMESPACE, oidlist);
      }
  
      if (newpath->addTemp && OidIsValid(myTempNamespace))
          oidlist = lcons_oid(myTempNamespace, oidlist);
  
      /*
       * Build the new stack entry, then insert it at the head of the list.
       */
      entry = (OverrideStackEntry *) palloc(sizeof(OverrideStackEntry));
      entry->searchPath = oidlist;
      entry->creationNamespace = firstNS;
      entry->nestLevel = GetCurrentTransactionNestLevel();
  
      overrideStack = lcons(entry, overrideStack);
  
      /* And make it active. */
      activeSearchPath = entry->searchPath;
      activeCreationNamespace = entry->creationNamespace;
      activeTempCreationPending = false;    /* XXX is this OK? */
  
      MemoryContextSwitchTo(oldcxt);
  }
  
  /*
   * PopOverrideSearchPath - undo a previous PushOverrideSearchPath
   *
   * Any push during a (sub)transaction will be popped automatically at abort.
   * But it's caller error if a push isn't popped in normal control flow.
   */
  void
  PopOverrideSearchPath(void)
  {
      OverrideStackEntry *entry;
  
      /* Sanity checks. */
      if (overrideStack == NIL)
          elog(ERROR, "bogus PopOverrideSearchPath call");
      entry = (OverrideStackEntry *) linitial(overrideStack);
      if (entry->nestLevel != GetCurrentTransactionNestLevel())
          elog(ERROR, "bogus PopOverrideSearchPath call");
  
      /* Pop the stack and free storage. */
      overrideStack = list_delete_first(overrideStack);
      list_free(entry->searchPath);
      pfree(entry);
  
      /* Activate the next level down. */
      if (overrideStack)
      {
          entry = (OverrideStackEntry *) linitial(overrideStack);
          activeSearchPath = entry->searchPath;
          activeCreationNamespace = entry->creationNamespace;
          activeTempCreationPending = false;    /* XXX is this OK? */
      }
      else
      {
          /* If not baseSearchPathValid, this is useless but harmless */
          activeSearchPath = baseSearchPath;
          activeCreationNamespace = baseCreationNamespace;
          activeTempCreationPending = baseTempCreationPending;
      }
  }
  
  
  /*
   * get_collation_oid - find a collation by possibly qualified name
   *
   * Note that this will only find collations that work with the current
   * database's encoding.
   */
  Oid
  get_collation_oid(List *name, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *collation_name;
      int32        dbencoding = GetDatabaseEncoding();
      Oid            namespaceId;
      Oid            colloid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(name, &schemaname, &collation_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              return InvalidOid;
  
          colloid = lookup_collation(collation_name, namespaceId, dbencoding);
          if (OidIsValid(colloid))
              return colloid;
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              colloid = lookup_collation(collation_name, namespaceId, dbencoding);
              if (OidIsValid(colloid))
                  return colloid;
          }
      }
  
      /* Not found in path */
      if (!missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("collation \"%s\" for encoding \"%s\" does not exist",
                          NameListToString(name), GetDatabaseEncodingName())));
      return InvalidOid;
  }
  
  /*
   * get_conversion_oid - find a conversion by possibly qualified name
   */
  Oid
  get_conversion_oid(List *name, bool missing_ok)
  {// #lizard forgives
      char       *schemaname;
      char       *conversion_name;
      Oid            namespaceId;
      Oid            conoid = InvalidOid;
      ListCell   *l;
  
      /* deconstruct the name list */
      DeconstructQualifiedName(name, &schemaname, &conversion_name);
  
      if (schemaname)
      {
          /* use exact schema given */
          namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
          if (missing_ok && !OidIsValid(namespaceId))
              conoid = InvalidOid;
          else
              conoid = GetSysCacheOid2(CONNAMENSP,
                                       PointerGetDatum(conversion_name),
                                       ObjectIdGetDatum(namespaceId));
      }
      else
      {
          /* search for it in search path */
          recomputeNamespacePath();
  
          foreach(l, activeSearchPath)
          {
              namespaceId = lfirst_oid(l);
  
              if (namespaceId == myTempNamespace)
                  continue;        /* do not look in temp namespace */
  
              conoid = GetSysCacheOid2(CONNAMENSP,
                                       PointerGetDatum(conversion_name),
                                       ObjectIdGetDatum(namespaceId));
              if (OidIsValid(conoid))
                  return conoid;
          }
      }
  
      /* Not found in path */
      if (!OidIsValid(conoid) && !missing_ok)
          ereport(ERROR,
                  (errcode(ERRCODE_UNDEFINED_OBJECT),
                   errmsg("conversion \"%s\" does not exist",
                          NameListToString(name))));
      return conoid;
  }
  
  /*
   * FindDefaultConversionProc - find default encoding conversion proc
   */
  Oid
  FindDefaultConversionProc(int32 for_encoding, int32 to_encoding)
  {
      Oid            proc;
      ListCell   *l;
  
      recomputeNamespacePath();
  
      foreach(l, activeSearchPath)
      {
          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;
  }
  
  /*
   * recomputeNamespacePath - recompute path derived variables if needed.
   */
  static void
  recomputeNamespacePath(void)
  {// #lizard forgives
      Oid            roleid = GetUserId();
      char       *rawname;
      List       *namelist;
      List       *oidlist;
      List       *newpath;
      ListCell   *l;
      bool        temp_missing;
      Oid            firstNS;
      MemoryContext oldcxt;
  
      /* Do nothing if an override search spec is active. */
      if (overrideStack)
          return;
  
      /* Do nothing if path is already valid. */
      if (baseSearchPathValid && namespaceUser == roleid)
          return;
  
      /* 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 */
              HeapTuple    tuple;
  
              tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
              if (HeapTupleIsValid(tuple))
              {
                  char       *rname;
  
                  rname = NameStr(((Form_pg_authid) GETSTRUCT(tuple))->rolname);
                  namespaceId = get_namespace_oid(rname, true);
                  ReleaseSysCache(tuple);
                  if (OidIsValid(namespaceId) &&
                      !list_member_oid(oidlist, namespaceId) &&
                      pg_namespace_aclcheck(namespaceId, roleid,
                                            ACL_USAGE) == ACLCHECK_OK &&
                      InvokeNamespaceSearchHook(namespaceId, false))
                      oidlist = lappend_oid(oidlist, namespaceId);
              }
          }
          else if (strcmp(curname, "pg_temp") == 0)
          {
              /* pg_temp --- substitute temp namespace, if any */
              if (OidIsValid(myTempNamespace))
              {
                  if (!list_member_oid(oidlist, myTempNamespace) &&
                      InvokeNamespaceSearchHook(myTempNamespace, false))
                      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 = get_namespace_oid(curname, true);
              if (OidIsValid(namespaceId) &&
                  !list_member_oid(oidlist, namespaceId) &&
                  pg_namespace_aclcheck(namespaceId, roleid,
                                        ACL_USAGE) == ACLCHECK_OK &&
                  InvokeNamespaceSearchHook(namespaceId, false))
                  oidlist = lappend_oid(oidlist, namespaceId);
          }
      }
  
      /*
       * 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.
       */
  #ifdef _PG_ORCL_
      if (support_oracle_compatible && !list_member_oid(oidlist, PG_ORACLE_NAMESPACE))
          oidlist = lappend_oid(oidlist, PG_ORACLE_NAMESPACE); // lcons_oid(PG_ORACLE_NAMESPACE, oidlist);
  #endif
  
      if (!list_member_oid(oidlist, PG_CATALOG_NAMESPACE))
          oidlist = lcons_oid(PG_CATALOG_NAMESPACE, oidlist);
  
      if (OidIsValid(myTempNamespace) &&
          !list_member_oid(oidlist, myTempNamespace))
          oidlist = lcons_oid(myTempNamespace, 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 variables. */
      list_free(baseSearchPath);
      baseSearchPath = newpath;
      baseCreationNamespace = firstNS;
      baseTempCreationPending = temp_missing;
  
      /* Mark the path valid. */
      baseSearchPathValid = true;
      namespaceUser = roleid;
  
      /* And make it active. */
      activeSearchPath = baseSearchPath;
      activeCreationNamespace = baseCreationNamespace;
      activeTempCreationPending = baseTempCreationPending;
  
      /* 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)
  {// #lizard forgives
      char        namespaceName[NAMEDATALEN];
      Oid            namespaceId;
      Oid            toastspaceId;
  
      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))));
  
      /*
       * Do not allow a Hot Standby session to make temp tables.  Aside from
       * problems with modifying the system catalogs, there is a naming
       * conflict: pg_temp_N belongs to the session with BackendId N on the
       * master, not to a hot standby session with the same BackendId.  We
       * should not be able to get here anyway due to XactReadOnly checks, but
       * let's just make real sure.  Note that this also backstops various
       * operations that allow XactReadOnly transactions to modify temp tables;
       * they'd need RecoveryInProgress checks if not for this.
       */
      if (RecoveryInProgress())
          ereport(ERROR,
                  (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
                   errmsg("cannot create temporary tables during recovery")));
  
      /* Parallel workers can't create temporary tables, either. */
      if (IsParallelWorker())
          ereport(ERROR,
                  (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
                   errmsg("cannot create temporary tables during a parallel operation")));
  
  #ifdef XCP
      /*
       * In case of distributed session use MyFirstBackendId for temp objects
       */
      if (OidIsValid(MyCoordId))
          snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d",
                   MyFirstBackendId);
      else
      /* fallback to default */
  #endif
      snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d", MyBackendId);
  
      namespaceId = get_namespace_oid(namespaceName, true);
      if (!OidIsValid(namespaceId))
      {
          /*
           * 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.
           */
          namespaceId = NamespaceCreate(namespaceName, BOOTSTRAP_SUPERUSERID,
                                        true);
          /* Advance command counter to make namespace visible */
          CommandCounterIncrement();
      }
      else
      {
          /*
           * If the namespace already exists, clean it out (in case the former
           * owner crashed without doing so).
           */
          RemoveTempRelations(namespaceId);
      }
  
      /*
       * If the corresponding toast-table namespace doesn't exist yet, create
       * it. (We assume there is no need to clean it out if it does exist, since
       * dropping a parent table should make its toast table go away.)
       */
  #ifdef XCP
      /*
       * In case of distributed session use MyFirstBackendId for temp objects
       */
      if (OidIsValid(MyCoordId))
          snprintf(namespaceName, sizeof(namespaceName), "pg_toast_temp_%d",
                   MyFirstBackendId);
      else
      /* fallback to default */
  #endif
      snprintf(namespaceName, sizeof(namespaceName), "pg_toast_temp_%d",
               MyBackendId);
  
      toastspaceId = get_namespace_oid(namespaceName, true);
      if (!OidIsValid(toastspaceId))
      {
          toastspaceId = NamespaceCreate(namespaceName, BOOTSTRAP_SUPERUSERID,
                                         true);
          /* Advance command counter to make namespace visible */
          CommandCounterIncrement();
      }
  
      /*
       * 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 = namespaceId;
      myTempToastNamespace = toastspaceId;
  
      /* It should not be done already. */
      AssertState(myTempNamespaceSubID == InvalidSubTransactionId);
  #ifdef XCP
      //if (!OidIsValid(MyCoordId))
  #endif
      myTempNamespaceSubID = GetCurrentSubTransactionId();
  
      baseSearchPathValid = false;    /* need to rebuild list */
  }
  
  /*
   * End-of-transaction cleanup for namespaces.
   */
  void
  AtEOXact_Namespace(bool isCommit, bool parallel)
  {// #lizard forgives
      /*
       * 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 && !parallel)
      {
          if (isCommit)
  #ifdef XCP
          {
              /*
               * During backend lifetime it may be assigned to different
               * distributed sessions, and each of them may create temp
               * namespace and set a callback. That may cause memory leak.
               * XXX is it ever possible to remove callbacks?
               */
              //if (!OidIsValid(MyCoordId))
                  before_shmem_exit(RemoveTempRelationsCallback, 0);
          }
  #else
              before_shmem_exit(RemoveTempRelationsCallback, 0);
  #endif
          else
          {
              myTempNamespace = InvalidOid;
              myTempToastNamespace = InvalidOid;
              baseSearchPathValid = false;    /* need to rebuild list */
          }
          myTempNamespaceSubID = InvalidSubTransactionId;
      }
  
      /*
       * Clean up if someone failed to do PopOverrideSearchPath
       */
      if (overrideStack)
      {
          if (isCommit)
              elog(WARNING, "leaked override search path");
          while (overrideStack)
          {
              OverrideStackEntry *entry;
  
              entry = (OverrideStackEntry *) linitial(overrideStack);
              overrideStack = list_delete_first(overrideStack);
              list_free(entry->searchPath);
              pfree(entry);
          }
          /* If not baseSearchPathValid, this is useless but harmless */
          activeSearchPath = baseSearchPath;
          activeCreationNamespace = baseCreationNamespace;
          activeTempCreationPending = baseTempCreationPending;
      }
  }
  
  /*
   * 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)
  {
      OverrideStackEntry *entry;
  
      if (myTempNamespaceSubID == mySubid)
      {
          if (isCommit)
              myTempNamespaceSubID = parentSubid;
          else
          {
              myTempNamespaceSubID = InvalidSubTransactionId;
              /* TEMP namespace creation failed, so reset state */
              myTempNamespace = InvalidOid;
              myTempToastNamespace = InvalidOid;
              baseSearchPathValid = false;    /* need to rebuild list */
          }
      }
  
      /*
       * Clean up if someone failed to do PopOverrideSearchPath
       */
      while (overrideStack)
      {
          entry = (OverrideStackEntry *) linitial(overrideStack);
          if (entry->nestLevel < GetCurrentTransactionNestLevel())
              break;
          if (isCommit)
              elog(WARNING, "leaked override search path");
          overrideStack = list_delete_first(overrideStack);
          list_free(entry->searchPath);
          pfree(entry);
      }
  
      /* Activate the next level down. */
      if (overrideStack)
      {
          entry = (OverrideStackEntry *) linitial(overrideStack);
          activeSearchPath = entry->searchPath;
          activeCreationNamespace = entry->creationNamespace;
          activeTempCreationPending = false;    /* XXX is this OK? */
      }
      else
      {
          /* If not baseSearchPathValid, this is useless but harmless */
          activeSearchPath = baseSearchPath;
          activeCreationNamespace = baseCreationNamespace;
          activeTempCreationPending = baseTempCreationPending;
      }
  }
  
  /*
   * 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).  Hence, specify SKIP_ORIGINAL.  It's also an INTERNAL
       * deletion, and we want to not drop any extensions that might happen to
       * own temp objects.
       */
      object.classId = NamespaceRelationId;
      object.objectId = tempNamespaceId;
      object.objectSubId = 0;
  
      performDeletion(&object, DROP_CASCADE,
                      PERFORM_DELETION_INTERNAL |
                      PERFORM_DELETION_QUIETLY |
                      PERFORM_DELETION_SKIP_ORIGINAL |
                      PERFORM_DELETION_SKIP_EXTENSIONS);
  }
  
  /*
   * Callback to remove temp relations at backend exit.
   */
  static void
  RemoveTempRelationsCallback(int code, Datum arg)
  {
      if (OidIsValid(myTempNamespace))    /* should always be true */
      {
          /* Need to ensure we have a usable transaction. */
          AbortOutOfAnyTransaction();
  #ifdef PGXC
          /*
           * When a backend closes, this insures that
           * transaction ID taken is unique in the cluster.
           */
          if (IsConnFromCoord())
              SetForceXidFromGTM(true);
  #endif
          StartTransactionCommand();
  
          RemoveTempRelations(myTempNamespace);
  
          CommitTransactionCommand();
  #ifdef PGXC
          if (IsConnFromCoord())
              SetForceXidFromGTM(false);
  #endif
      }
  }
  
  /*
   * Remove all temp tables from the temporary namespace.
   */
  void
  ResetTempTableNamespace(void)
  {
      if (OidIsValid(myTempNamespace))
          RemoveTempRelations(myTempNamespace);
  #ifdef XCP
      else if (OidIsValid(MyCoordId))
      {
          char        namespaceName[NAMEDATALEN];
          Oid            namespaceId;
  
          snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d",
                   MyFirstBackendId);
  
          namespaceId = get_namespace_oid(namespaceName, true);
          if (OidIsValid(namespaceId))
              RemoveTempRelations(namespaceId);
      }
  #endif
  }
  
  
  #ifdef XCP
  /*
   * Reset myTempNamespace so it will be reinitialized after backend is assigned
   * to a different session.
   */
  void
  ForgetTempTableNamespace(void)
  {
      /* If the namespace exists and need to be cleaned up do that */
      if (OidIsValid(myTempNamespace) &&
              myTempNamespaceSubID != InvalidSubTransactionId)
      {
          elog(WARNING, "leaked temp namespace clean up callback");
          RemoveTempRelations(myTempNamespace);
      }
      myTempNamespace = InvalidOid;
      myTempToastNamespace = InvalidOid;
      baseSearchPathValid = false;        /* need to rebuild list */
      myTempNamespaceSubID = InvalidSubTransactionId;
  }
  #endif
  
  
  /*
   * Routines for handling the GUC variable 'search_path'.
   */
  
  /* check_hook: validate new search_path value */
  bool
  check_search_path(char **newval, void **extra, GucSource source)
  {
      char       *rawname;
      List       *namelist;
  
      /* Need a modifiable copy of string */
      rawname = pstrdup(*newval);
  
      /* Parse string into list of identifiers */
      if (!SplitIdentifierString(rawname, ',', &namelist))
      {
          /* syntax error in name list */
          GUC_check_errdetail("List syntax is invalid.");
          pfree(rawname);
          list_free(namelist);
          return false;
      }
  
      /*
       * We used to try to check that the named schemas exist, but there are
       * many valid use-cases for having search_path settings that include
       * schemas that don't exist; and often, we are not inside a transaction
       * here and so can't consult the system catalogs anyway.  So now, the only
       * requirement is syntactic validity of the identifier list.
       */
  
      pfree(rawname);
      list_free(namelist);
  
      return true;
  }
  
  /* assign_hook: do extra actions as needed */
  void
  assign_search_path(const char *newval, void *extra)
  {
      /*
       * 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, or outside a transaction.
       */
      baseSearchPathValid = false;
  }
  
  /*
   * 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);
          baseSearchPath = list_make1_oid(PG_CATALOG_NAMESPACE);
          MemoryContextSwitchTo(oldcxt);
          baseCreationNamespace = PG_CATALOG_NAMESPACE;
          baseTempCreationPending = false;
          baseSearchPathValid = true;
          namespaceUser = GetUserId();
          activeSearchPath = baseSearchPath;
          activeCreationNamespace = baseCreationNamespace;
          activeTempCreationPending = baseTempCreationPending;
      }
      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 */
          baseSearchPathValid = false;
      }
  }
  
  /*
   * NamespaceCallback
   *        Syscache inval callback function
   */
  static void
  NamespaceCallback(Datum arg, int cacheid, uint32 hashvalue)
  {
      /* Force search path to be recomputed on next use */
      baseSearchPathValid = false;
  }
  
  /*
   * 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 (activeTempCreationPending)
      {
          InitTempTableNamespace();
          recomputeNamespacePath();
      }
  
      result = list_copy(activeSearchPath);
      if (!includeImplicit)
      {
          while (result && linitial_oid(result) != activeCreationNamespace)
              result = list_delete_first(result);
      }
  
      return result;
  }
  
  /*
   * Fetch the active search path into a caller-allocated array of OIDs.
   * Returns the number of path entries.  (If this is more than sarray_len,
   * then the data didn't fit and is not all stored.)
   *
   * The returned list always includes the implicitly-prepended namespaces,
   * but never includes the temp namespace.  (This is suitable for existing
   * users, which would want to ignore the temp namespace anyway.)  This
   * definition allows us to not worry about initializing the temp namespace.
   */
  int
  fetch_search_path_array(Oid *sarray, int sarray_len)
  {
      int            count = 0;
      ListCell   *l;
  
      recomputeNamespacePath();
  
      foreach(l, activeSearchPath)
      {
          Oid            namespaceId = lfirst_oid(l);
  
          if (namespaceId == myTempNamespace)
              continue;            /* do not include temp namespace */
  
          if (count < sarray_len)
              sarray[count] = namespaceId;
          count++;
      }
  
      return count;
  }
  
  
  /*
   * 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
   * always use an up-to-date snapshot and so might see the object as already
   * gone when it's still visible to the transaction snapshot.  (There is no race
   * condition in the current coding because we don't accept sinval messages
   * between the SearchSysCacheExists test and the subsequent lookup.)
   */
  
  Datum
  pg_table_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(RELOID, 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 (!SearchSysCacheExists1(TYPEOID, 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 (!SearchSysCacheExists1(PROCOID, 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 (!SearchSysCacheExists1(OPEROID, 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 (!SearchSysCacheExists1(CLAOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(OpclassIsVisible(oid));
  }
  
  Datum
  pg_opfamily_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(OPFAMILYOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(OpfamilyIsVisible(oid));
  }
  
  Datum
  pg_collation_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(COLLOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(CollationIsVisible(oid));
  }
  
  Datum
  pg_conversion_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(CONVOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(ConversionIsVisible(oid));
  }
  
  Datum
  pg_statistics_obj_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(STATEXTOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(StatisticsObjIsVisible(oid));
  }
  
  Datum
  pg_ts_parser_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(TSPARSEROID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(TSParserIsVisible(oid));
  }
  
  Datum
  pg_ts_dict_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(TSDICTOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(TSDictionaryIsVisible(oid));
  }
  
  Datum
  pg_ts_template_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(TSTEMPLATEOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(TSTemplateIsVisible(oid));
  }
  
  Datum
  pg_ts_config_is_visible(PG_FUNCTION_ARGS)
  {
      Oid            oid = PG_GETARG_OID(0);
  
      if (!SearchSysCacheExists1(TSCONFIGOID, ObjectIdGetDatum(oid)))
          PG_RETURN_NULL();
  
      PG_RETURN_BOOL(TSConfigIsVisible(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));
  }
  
  
  #ifdef XCP
  /*
   * FindTemporaryNamespace
   *     If this is secondary backend of distributed session check if primary backend
   *     of the same session created temporary namespace and wire it up if it is the
   *     case, instead of creating new.
   */
  static void
  FindTemporaryNamespace(void)
  {
      char        namespaceName[NAMEDATALEN];
  
      Assert(!OidIsValid(myTempNamespace));
  
      /*
       * We need distribution session identifier to find the namespace.
       */
      if (!OidIsValid(MyCoordId))
          return;
  
      /*
       * Look up namespace by name. This code should be in synch with
       * InitTempTableNamespace.
       */
      snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d",
               MyFirstBackendId);
      myTempNamespace = get_namespace_oid(namespaceName, true);
      /* Same for the toast namespace */
      if (OidIsValid(myTempNamespace))
      {
          snprintf(namespaceName, sizeof(namespaceName), "pg_toast_temp_%d",
                   MyFirstBackendId);
          myTempToastNamespace = get_namespace_oid(namespaceName, true);
          baseSearchPathValid = false;    /* need to rebuild list */
      }
  }
  #endif
  
  