text: /*-------------------------------------------------------------------------
   *
   * parse_relation.c
   *	  parser support routines dealing with relations
   *
   * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/parser/parse_relation.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include <ctype.h>
  
  #include "access/htup_details.h"
  #include "access/sysattr.h"
  #include "catalog/heap.h"
  #include "catalog/namespace.h"
  #include "catalog/pg_type.h"
  #include "funcapi.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "parser/parsetree.h"
  #include "parser/parse_enr.h"
  #include "parser/parse_relation.h"
  #include "parser/parse_type.h"
  #include "storage/lmgr.h"
  #include "utils/builtins.h"
  #include "utils/lsyscache.h"
  #include "utils/rel.h"
  #include "utils/syscache.h"
  #include "utils/varlena.h"
  
  
  #define MAX_FUZZY_DISTANCE				3
  
  static RangeTblEntry *scanNameSpaceForRefname(ParseState *pstate,
  						const char *refname, int location);
  static RangeTblEntry *scanNameSpaceForRelid(ParseState *pstate, Oid relid,
  					  int location);
  static void check_lateral_ref_ok(ParseState *pstate, ParseNamespaceItem *nsitem,
  					 int location);
  static void markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
  					 int rtindex, AttrNumber col);
  static void expandRelation(Oid relid, Alias *eref,
  			   int rtindex, int sublevels_up,
  			   int location, bool include_dropped,
  			   List **colnames, List **colvars);
  static void expandTupleDesc(TupleDesc tupdesc, Alias *eref,
  				int count, int offset,
  				int rtindex, int sublevels_up,
  				int location, bool include_dropped,
  				List **colnames, List **colvars);
  static int	specialAttNum(const char *attname);
  static bool isQueryUsingTempRelation_walker(Node *node, void *context);
  
  
  /*
   * refnameRangeTblEntry
   *	  Given a possibly-qualified refname, look to see if it matches any RTE.
   *	  If so, return a pointer to the RangeTblEntry; else return NULL.
   *
   *	  Optionally get RTE's nesting depth (0 = current) into *sublevels_up.
   *	  If sublevels_up is NULL, only consider items at the current nesting
   *	  level.
   *
   * An unqualified refname (schemaname == NULL) can match any RTE with matching
   * alias, or matching unqualified relname in the case of alias-less relation
   * RTEs.  It is possible that such a refname matches multiple RTEs in the
   * nearest nesting level that has a match; if so, we report an error via
   * ereport().
   *
   * A qualified refname (schemaname != NULL) can only match a relation RTE
   * that (a) has no alias and (b) is for the same relation identified by
   * schemaname.refname.  In this case we convert schemaname.refname to a
   * relation OID and search by relid, rather than by alias name.  This is
   * peculiar, but it's what SQL says to do.
   */
  RangeTblEntry *
  refnameRangeTblEntry(ParseState *pstate,
  					 const char *schemaname,
  					 const char *refname,
  					 int location,
  					 int *sublevels_up)
  {
  	Oid			relId = InvalidOid;
  
  	if (sublevels_up)
  		*sublevels_up = 0;
  
  	if (schemaname != NULL)
  	{
  		Oid			namespaceId;
  
  		/*
  		 * We can use LookupNamespaceNoError() here because we are only
  		 * interested in finding existing RTEs.  Checking USAGE permission on
  		 * the schema is unnecessary since it would have already been checked
  		 * when the RTE was made.  Furthermore, we want to report "RTE not
  		 * found", not "no permissions for schema", if the name happens to
  		 * match a schema name the user hasn't got access to.
  		 */
  		namespaceId = LookupNamespaceNoError(schemaname);
  		if (!OidIsValid(namespaceId))
  			return NULL;
  		relId = get_relname_relid(refname, namespaceId);
  		if (!OidIsValid(relId))
  			return NULL;
  	}
  
  	while (pstate != NULL)
  	{
  		RangeTblEntry *result;
  
  		if (OidIsValid(relId))
  			result = scanNameSpaceForRelid(pstate, relId, location);
  		else
  			result = scanNameSpaceForRefname(pstate, refname, location);
  
  		if (result)
  			return result;
  
  		if (sublevels_up)
  			(*sublevels_up)++;
  		else
  			break;
  
  		pstate = pstate->parentParseState;
  	}
  	return NULL;
  }
  
  /*
   * Search the query's table namespace for an RTE matching the
   * given unqualified refname.  Return the RTE if a unique match, or NULL
   * if no match.  Raise error if multiple matches.
   *
   * Note: it might seem that we shouldn't have to worry about the possibility
   * of multiple matches; after all, the SQL standard disallows duplicate table
   * aliases within a given SELECT level.  Historically, however, Postgres has
   * been laxer than that.  For example, we allow
   *		SELECT ... FROM tab1 x CROSS JOIN (tab2 x CROSS JOIN tab3 y) z
   * on the grounds that the aliased join (z) hides the aliases within it,
   * therefore there is no conflict between the two RTEs named "x".  However,
   * if tab3 is a LATERAL subquery, then from within the subquery both "x"es
   * are visible.  Rather than rejecting queries that used to work, we allow
   * this situation, and complain only if there's actually an ambiguous
   * reference to "x".
   */
  static RangeTblEntry *
  scanNameSpaceForRefname(ParseState *pstate, const char *refname, int location)
  {
  	RangeTblEntry *result = NULL;
  	ListCell   *l;
  
  	foreach(l, pstate->p_namespace)
  	{
  		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(l);
  		RangeTblEntry *rte = nsitem->p_rte;
  
  		/* Ignore columns-only items */
  		if (!nsitem->p_rel_visible)
  			continue;
  		/* If not inside LATERAL, ignore lateral-only items */
  		if (nsitem->p_lateral_only && !pstate->p_lateral_active)
  			continue;
  
  		if (strcmp(rte->eref->aliasname, refname) == 0)
  		{
  			if (result)
  				ereport(ERROR,
  						(errcode(ERRCODE_AMBIGUOUS_ALIAS),
  						 errmsg("table reference \"%s\" is ambiguous",
  								refname),
  						 parser_errposition(pstate, location)));
  			check_lateral_ref_ok(pstate, nsitem, location);
  			result = rte;
  		}
  	}
  	return result;
  }
  
  /*
   * Search the query's table namespace for a relation RTE matching the
   * given relation OID.  Return the RTE if a unique match, or NULL
   * if no match.  Raise error if multiple matches.
   *
   * See the comments for refnameRangeTblEntry to understand why this
   * acts the way it does.
   */
  static RangeTblEntry *
  scanNameSpaceForRelid(ParseState *pstate, Oid relid, int location)
  {
  	RangeTblEntry *result = NULL;
  	ListCell   *l;
  
  	foreach(l, pstate->p_namespace)
  	{
  		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(l);
  		RangeTblEntry *rte = nsitem->p_rte;
  
  		/* Ignore columns-only items */
  		if (!nsitem->p_rel_visible)
  			continue;
  		/* If not inside LATERAL, ignore lateral-only items */
  		if (nsitem->p_lateral_only && !pstate->p_lateral_active)
  			continue;
  
  		/* yes, the test for alias == NULL should be there... */
  		if (rte->rtekind == RTE_RELATION &&
  			rte->relid == relid &&
  			rte->alias == NULL)
  		{
  			if (result)
  				ereport(ERROR,
  						(errcode(ERRCODE_AMBIGUOUS_ALIAS),
  						 errmsg("table reference %u is ambiguous",
  								relid),
  						 parser_errposition(pstate, location)));
  			check_lateral_ref_ok(pstate, nsitem, location);
  			result = rte;
  		}
  	}
  	return result;
  }
  
  /*
   * Search the query's CTE namespace for a CTE matching the given unqualified
   * refname.  Return the CTE (and its levelsup count) if a match, or NULL
   * if no match.  We need not worry about multiple matches, since parse_cte.c
   * rejects WITH lists containing duplicate CTE names.
   */
  CommonTableExpr *
  scanNameSpaceForCTE(ParseState *pstate, const char *refname,
  					Index *ctelevelsup)
  {
  	Index		levelsup;
  
  	for (levelsup = 0;
  		 pstate != NULL;
  		 pstate = pstate->parentParseState, levelsup++)
  	{
  		ListCell   *lc;
  
  		foreach(lc, pstate->p_ctenamespace)
  		{
  			CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
  
  			if (strcmp(cte->ctename, refname) == 0)
  			{
  				*ctelevelsup = levelsup;
  				return cte;
  			}
  		}
  	}
  	return NULL;
  }
  
  /*
   * Search for a possible "future CTE", that is one that is not yet in scope
   * according to the WITH scoping rules.  This has nothing to do with valid
   * SQL semantics, but it's important for error reporting purposes.
   */
  static bool
  isFutureCTE(ParseState *pstate, const char *refname)
  {
  	for (; pstate != NULL; pstate = pstate->parentParseState)
  	{
  		ListCell   *lc;
  
  		foreach(lc, pstate->p_future_ctes)
  		{
  			CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
  
  			if (strcmp(cte->ctename, refname) == 0)
  				return true;
  		}
  	}
  	return false;
  }
  
  /*
   * Search the query's ephemeral named relation namespace for a relation
   * matching the given unqualified refname.
   */
  bool
  scanNameSpaceForENR(ParseState *pstate, const char *refname)
  {
  	return name_matches_visible_ENR(pstate, refname);
  }
  
  /*
   * searchRangeTableForRel
   *	  See if any RangeTblEntry could possibly match the RangeVar.
   *	  If so, return a pointer to the RangeTblEntry; else return NULL.
   *
   * This is different from refnameRangeTblEntry in that it considers every
   * entry in the ParseState's rangetable(s), not only those that are currently
   * visible in the p_namespace list(s).  This behavior is invalid per the SQL
   * spec, and it may give ambiguous results (there might be multiple equally
   * valid matches, but only one will be returned).  This must be used ONLY
   * as a heuristic in giving suitable error messages.  See errorMissingRTE.
   *
   * Notice that we consider both matches on actual relation (or CTE) name
   * and matches on alias.
   */
  static RangeTblEntry *
  searchRangeTableForRel(ParseState *pstate, RangeVar *relation)
  {
  	const char *refname = relation->relname;
  	Oid			relId = InvalidOid;
  	CommonTableExpr *cte = NULL;
  	bool		isenr = false;
  	Index		ctelevelsup = 0;
  	Index		levelsup;
  
  	/*
  	 * If it's an unqualified name, check for possible CTE matches. A CTE
  	 * hides any real relation matches.  If no CTE, look for a matching
  	 * relation.
  	 *
  	 * NB: It's not critical that RangeVarGetRelid return the correct answer
  	 * here in the face of concurrent DDL.  If it doesn't, the worst case
  	 * scenario is a less-clear error message.  Also, the tables involved in
  	 * the query are already locked, which reduces the number of cases in
  	 * which surprising behavior can occur.  So we do the name lookup
  	 * unlocked.
  	 */
  	if (!relation->schemaname)
  	{
  		cte = scanNameSpaceForCTE(pstate, refname, &ctelevelsup);
  		if (!cte)
  			isenr = scanNameSpaceForENR(pstate, refname);
  	}
  
  	if (!cte && !isenr)
  		relId = RangeVarGetRelid(relation, NoLock, true);
  
  	/* Now look for RTEs matching either the relation/CTE/ENR or the alias */
  	for (levelsup = 0;
  		 pstate != NULL;
  		 pstate = pstate->parentParseState, levelsup++)
  	{
  		ListCell   *l;
  
  		foreach(l, pstate->p_rtable)
  		{
  			RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
  
  			if (rte->rtekind == RTE_RELATION &&
  				OidIsValid(relId) &&
  				rte->relid == relId)
  				return rte;
  			if (rte->rtekind == RTE_CTE &&
  				cte != NULL &&
  				rte->ctelevelsup + levelsup == ctelevelsup &&
  				strcmp(rte->ctename, refname) == 0)
  				return rte;
  			if (rte->rtekind == RTE_NAMEDTUPLESTORE &&
  				isenr &&
  				strcmp(rte->enrname, refname) == 0)
  				return rte;
  			if (strcmp(rte->eref->aliasname, refname) == 0)
  				return rte;
  		}
  	}
  	return NULL;
  }
  
  /*
   * Check for relation-name conflicts between two namespace lists.
   * Raise an error if any is found.
   *
   * Note: we assume that each given argument does not contain conflicts
   * itself; we just want to know if the two can be merged together.
   *
   * Per SQL, two alias-less plain relation RTEs do not conflict even if
   * they have the same eref->aliasname (ie, same relation name), if they
   * are for different relation OIDs (implying they are in different schemas).
   *
   * We ignore the lateral-only flags in the namespace items: the lists must
   * not conflict, even when all items are considered visible.  However,
   * columns-only items should be ignored.
   */
  void
  checkNameSpaceConflicts(ParseState *pstate, List *namespace1,
  						List *namespace2)
  {
  	ListCell   *l1;
  
  	foreach(l1, namespace1)
  	{
  		ParseNamespaceItem *nsitem1 = (ParseNamespaceItem *) lfirst(l1);
  		RangeTblEntry *rte1 = nsitem1->p_rte;
  		const char *aliasname1 = rte1->eref->aliasname;
  		ListCell   *l2;
  
  		if (!nsitem1->p_rel_visible)
  			continue;
  
  		foreach(l2, namespace2)
  		{
  			ParseNamespaceItem *nsitem2 = (ParseNamespaceItem *) lfirst(l2);
  			RangeTblEntry *rte2 = nsitem2->p_rte;
  
  			if (!nsitem2->p_rel_visible)
  				continue;
  			if (strcmp(rte2->eref->aliasname, aliasname1) != 0)
  				continue;		/* definitely no conflict */
  			if (rte1->rtekind == RTE_RELATION && rte1->alias == NULL &&
  				rte2->rtekind == RTE_RELATION && rte2->alias == NULL &&
  				rte1->relid != rte2->relid)
  				continue;		/* no conflict per SQL rule */
  			ereport(ERROR,
  					(errcode(ERRCODE_DUPLICATE_ALIAS),
  					 errmsg("table name \"%s\" specified more than once",
  							aliasname1)));
  		}
  	}
  }
  
  /*
   * Complain if a namespace item is currently disallowed as a LATERAL reference.
   * This enforces both SQL:2008's rather odd idea of what to do with a LATERAL
   * reference to the wrong side of an outer join, and our own prohibition on
   * referencing the target table of an UPDATE or DELETE as a lateral reference
   * in a FROM/USING clause.
   *
   * Convenience subroutine to avoid multiple copies of a rather ugly ereport.
   */
  static void
  check_lateral_ref_ok(ParseState *pstate, ParseNamespaceItem *nsitem,
  					 int location)
  {
  	if (nsitem->p_lateral_only && !nsitem->p_lateral_ok)
  	{
  		/* SQL:2008 demands this be an error, not an invisible item */
  		RangeTblEntry *rte = nsitem->p_rte;
  		char	   *refname = rte->eref->aliasname;
  
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  				 errmsg("invalid reference to FROM-clause entry for table \"%s\"",
  						refname),
  				 (rte == pstate->p_target_rangetblentry) ?
  				 errhint("There is an entry for table \"%s\", but it cannot be referenced from this part of the query.",
  						 refname) :
  				 errdetail("The combining JOIN type must be INNER or LEFT for a LATERAL reference."),
  				 parser_errposition(pstate, location)));
  	}
  }
  
  /*
   * given an RTE, return RT index (starting with 1) of the entry,
   * and optionally get its nesting depth (0 = current).  If sublevels_up
   * is NULL, only consider rels at the current nesting level.
   * Raises error if RTE not found.
   */
  int
  RTERangeTablePosn(ParseState *pstate, RangeTblEntry *rte, int *sublevels_up)
  {
  	int			index;
  	ListCell   *l;
  
  	if (sublevels_up)
  		*sublevels_up = 0;
  
  	while (pstate != NULL)
  	{
  		index = 1;
  		foreach(l, pstate->p_rtable)
  		{
  			if (rte == (RangeTblEntry *) lfirst(l))
  				return index;
  			index++;
  		}
  		pstate = pstate->parentParseState;
  		if (sublevels_up)
  			(*sublevels_up)++;
  		else
  			break;
  	}
  
  	elog(ERROR, "RTE not found (internal error)");
  	return 0;					/* keep compiler quiet */
  }
  
  /*
   * Given an RT index and nesting depth, find the corresponding RTE.
   * This is the inverse of RTERangeTablePosn.
   */
  RangeTblEntry *
  GetRTEByRangeTablePosn(ParseState *pstate,
  					   int varno,
  					   int sublevels_up)
  {
  	while (sublevels_up-- > 0)
  	{
  		pstate = pstate->parentParseState;
  		Assert(pstate != NULL);
  	}
  	Assert(varno > 0 && varno <= list_length(pstate->p_rtable));
  	return rt_fetch(varno, pstate->p_rtable);
  }
  
  /*
   * Fetch the CTE for a CTE-reference RTE.
   *
   * rtelevelsup is the number of query levels above the given pstate that the
   * RTE came from.  Callers that don't have this information readily available
   * may pass -1 instead.
   */
  CommonTableExpr *
  GetCTEForRTE(ParseState *pstate, RangeTblEntry *rte, int rtelevelsup)
  {
  	Index		levelsup;
  	ListCell   *lc;
  
  	/* Determine RTE's levelsup if caller didn't know it */
  	if (rtelevelsup < 0)
  		(void) RTERangeTablePosn(pstate, rte, &rtelevelsup);
  
  	Assert(rte->rtekind == RTE_CTE);
  	levelsup = rte->ctelevelsup + rtelevelsup;
  	while (levelsup-- > 0)
  	{
  		pstate = pstate->parentParseState;
  		if (!pstate)			/* shouldn't happen */
  			elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
  	}
  	foreach(lc, pstate->p_ctenamespace)
  	{
  		CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
  
  		if (strcmp(cte->ctename, rte->ctename) == 0)
  			return cte;
  	}
  	/* shouldn't happen */
  	elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
  	return NULL;				/* keep compiler quiet */
  }
  
  /*
   * updateFuzzyAttrMatchState
   *	  Using Levenshtein distance, consider if column is best fuzzy match.
   */
  static void
  updateFuzzyAttrMatchState(int fuzzy_rte_penalty,
  						  FuzzyAttrMatchState *fuzzystate, RangeTblEntry *rte,
  						  const char *actual, const char *match, int attnum)
  {
  	int			columndistance;
  	int			matchlen;
  
  	/* Bail before computing the Levenshtein distance if there's no hope. */
  	if (fuzzy_rte_penalty > fuzzystate->distance)
  		return;
  
  	/*
  	 * Outright reject dropped columns, which can appear here with apparent
  	 * empty actual names, per remarks within scanRTEForColumn().
  	 */
  	if (actual[0] == '\0')
  		return;
  
  	/* Use Levenshtein to compute match distance. */
  	matchlen = strlen(match);
  	columndistance =
  		varstr_levenshtein_less_equal(actual, strlen(actual), match, matchlen,
  									  1, 1, 1,
  									  fuzzystate->distance + 1
  									  - fuzzy_rte_penalty,
  									  true);
  
  	/*
  	 * If more than half the characters are different, don't treat it as a
  	 * match, to avoid making ridiculous suggestions.
  	 */
  	if (columndistance > matchlen / 2)
  		return;
  
  	/*
  	 * From this point on, we can ignore the distinction between the RTE-name
  	 * distance and the column-name distance.
  	 */
  	columndistance += fuzzy_rte_penalty;
  
  	/*
  	 * If the new distance is less than or equal to that of the best match
  	 * found so far, update fuzzystate.
  	 */
  	if (columndistance < fuzzystate->distance)
  	{
  		/* Store new lowest observed distance for RTE */
  		fuzzystate->distance = columndistance;
  		fuzzystate->rfirst = rte;
  		fuzzystate->first = attnum;
  		fuzzystate->rsecond = NULL;
  		fuzzystate->second = InvalidAttrNumber;
  	}
  	else if (columndistance == fuzzystate->distance)
  	{
  		/*
  		 * This match distance may equal a prior match within this same range
  		 * table.  When that happens, the prior match may also be given, but
  		 * only if there is no more than two equally distant matches from the
  		 * RTE (in turn, our caller will only accept two equally distant
  		 * matches overall).
  		 */
  		if (AttributeNumberIsValid(fuzzystate->second))
  		{
  			/* Too many RTE-level matches */
  			fuzzystate->rfirst = NULL;
  			fuzzystate->first = InvalidAttrNumber;
  			fuzzystate->rsecond = NULL;
  			fuzzystate->second = InvalidAttrNumber;
  			/* Clearly, distance is too low a bar (for *any* RTE) */
  			fuzzystate->distance = columndistance - 1;
  		}
  		else if (AttributeNumberIsValid(fuzzystate->first))
  		{
  			/* Record as provisional second match for RTE */
  			fuzzystate->rsecond = rte;
  			fuzzystate->second = attnum;
  		}
  		else if (fuzzystate->distance <= MAX_FUZZY_DISTANCE)
  		{
  			/*
  			 * Record as provisional first match (this can occasionally occur
  			 * because previous lowest distance was "too low a bar", rather
  			 * than being associated with a real match)
  			 */
  			fuzzystate->rfirst = rte;
  			fuzzystate->first = attnum;
  		}
  	}
  }
  
  /*
   * scanRTEForColumn
   *	  Search the column names of a single RTE for the given name.
   *	  If found, return an appropriate Var node, else return NULL.
   *	  If the name proves ambiguous within this RTE, raise error.
   *
   * Side effect: if we find a match, mark the RTE as requiring read access
   * for the column.
   *
   * Additional side effect: if fuzzystate is non-NULL, check non-system columns
   * for an approximate match and update fuzzystate accordingly.
   */
  Node *
  scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte, const char *colname,
  				 int location, int fuzzy_rte_penalty,
  				 FuzzyAttrMatchState *fuzzystate)
  {
  	Node	   *result = NULL;
  	int			attnum = 0;
  	Var		   *var;
  	ListCell   *c;
  
  	/*
  	 * Scan the user column names (or aliases) for a match. Complain if
  	 * multiple matches.
  	 *
  	 * Note: eref->colnames may include entries for dropped columns, but those
  	 * will be empty strings that cannot match any legal SQL identifier, so we
  	 * don't bother to test for that case here.
  	 *
  	 * Should this somehow go wrong and we try to access a dropped column,
  	 * we'll still catch it by virtue of the checks in
  	 * get_rte_attribute_type(), which is called by make_var().  That routine
  	 * has to do a cache lookup anyway, so the check there is cheap.  Callers
  	 * interested in finding match with shortest distance need to defend
  	 * against this directly, though.
  	 */
  	foreach(c, rte->eref->colnames)
  	{
  		const char *attcolname = strVal(lfirst(c));
  
  		attnum++;
  		if (strcmp(attcolname, colname) == 0)
  		{
  			if (result)
  				ereport(ERROR,
  						(errcode(ERRCODE_AMBIGUOUS_COLUMN),
  						 errmsg("column reference \"%s\" is ambiguous",
  								colname),
  						 parser_errposition(pstate, location)));
  			var = make_var(pstate, rte, attnum, location);
  			/* Require read access to the column */
  			markVarForSelectPriv(pstate, var, rte);
  			result = (Node *) var;
  		}
  
  		/* Updating fuzzy match state, if provided. */
  		if (fuzzystate != NULL)
  			updateFuzzyAttrMatchState(fuzzy_rte_penalty, fuzzystate,
  									  rte, attcolname, colname, attnum);
  	}
  
  	/*
  	 * If we have a unique match, return it.  Note that this allows a user
  	 * alias to override a system column name (such as OID) without error.
  	 */
  	if (result)
  		return result;
  
  	/*
  	 * If the RTE represents a real relation, consider system column names.
  	 * Composites are only used for pseudo-relations like ON CONFLICT's
  	 * excluded.
  	 */
  	if (rte->rtekind == RTE_RELATION &&
  		rte->relkind != RELKIND_COMPOSITE_TYPE)
  	{
  		/* quick check to see if name could be a system column */
  		attnum = specialAttNum(colname);
  
  		/* In constraint check, no system column is allowed except tableOid */
  		if (pstate->p_expr_kind == EXPR_KIND_CHECK_CONSTRAINT &&
  			attnum < InvalidAttrNumber && attnum != TableOidAttributeNumber)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  					 errmsg("system column \"%s\" reference in check constraint is invalid",
  							colname),
  					 parser_errposition(pstate, location)));
  
  		if (attnum != InvalidAttrNumber)
  		{
  			/* now check to see if column actually is defined */
  			if (SearchSysCacheExists2(ATTNUM,
  									  ObjectIdGetDatum(rte->relid),
  									  Int16GetDatum(attnum)))
  			{
  				var = make_var(pstate, rte, attnum, location);
  				/* Require read access to the column */
  				markVarForSelectPriv(pstate, var, rte);
  				result = (Node *) var;
  			}
  		}
  	}
  
  	return result;
  }
  
  /*
   * colNameToVar
   *	  Search for an unqualified column name.
   *	  If found, return the appropriate Var node (or expression).
   *	  If not found, return NULL.  If the name proves ambiguous, raise error.
   *	  If localonly is true, only names in the innermost query are considered.
   */
  Node *
  colNameToVar(ParseState *pstate, const char *colname, bool localonly,
  			 int location)
  {
  	Node	   *result = NULL;
  	ParseState *orig_pstate = pstate;
  
  	while (pstate != NULL)
  	{
  		ListCell   *l;
  
  		foreach(l, pstate->p_namespace)
  		{
  			ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(l);
  			RangeTblEntry *rte = nsitem->p_rte;
  			Node	   *newresult;
  
  			/* Ignore table-only items */
  			if (!nsitem->p_cols_visible)
  				continue;
  			/* If not inside LATERAL, ignore lateral-only items */
  			if (nsitem->p_lateral_only && !pstate->p_lateral_active)
  				continue;
  
  			/* use orig_pstate here to get the right sublevels_up */
  			newresult = scanRTEForColumn(orig_pstate, rte, colname, location,
  										 0, NULL);
  
  			if (newresult)
  			{
  				if (result)
  					ereport(ERROR,
  							(errcode(ERRCODE_AMBIGUOUS_COLUMN),
  							 errmsg("column reference \"%s\" is ambiguous",
  									colname),
  							 parser_errposition(pstate, location)));
  				check_lateral_ref_ok(pstate, nsitem, location);
  				result = newresult;
  			}
  		}
  
  		if (result != NULL || localonly)
  			break;				/* found, or don't want to look at parent */
  
  		pstate = pstate->parentParseState;
  	}
  
  	return result;
  }
  
  /*
   * searchRangeTableForCol
   *	  See if any RangeTblEntry could possibly provide the given column name (or
   *	  find the best match available).  Returns state with relevant details.
   *
   * This is different from colNameToVar in that it considers every entry in
   * the ParseState's rangetable(s), not only those that are currently visible
   * in the p_namespace list(s).  This behavior is invalid per the SQL spec,
   * and it may give ambiguous results (there might be multiple equally valid
   * matches, but only one will be returned).  This must be used ONLY as a
   * heuristic in giving suitable error messages.  See errorMissingColumn.
   *
   * This function is also different in that it will consider approximate
   * matches -- if the user entered an alias/column pair that is only slightly
   * different from a valid pair, we may be able to infer what they meant to
   * type and provide a reasonable hint.
   *
   * The FuzzyAttrMatchState will have 'rfirst' pointing to the best RTE
   * containing the most promising match for the alias and column name.  If
   * the alias and column names match exactly, 'first' will be InvalidAttrNumber;
   * otherwise, it will be the attribute number for the match.  In the latter
   * case, 'rsecond' may point to a second, equally close approximate match,
   * and 'second' will contain the attribute number for the second match.
   */
  static FuzzyAttrMatchState *
  searchRangeTableForCol(ParseState *pstate, const char *alias, const char *colname,
  					   int location)
  {
  	ParseState *orig_pstate = pstate;
  	FuzzyAttrMatchState *fuzzystate = palloc(sizeof(FuzzyAttrMatchState));
  
  	fuzzystate->distance = MAX_FUZZY_DISTANCE + 1;
  	fuzzystate->rfirst = NULL;
  	fuzzystate->rsecond = NULL;
  	fuzzystate->first = InvalidAttrNumber;
  	fuzzystate->second = InvalidAttrNumber;
  
  	while (pstate != NULL)
  	{
  		ListCell   *l;
  
  		foreach(l, pstate->p_rtable)
  		{
  			RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
  			int			fuzzy_rte_penalty = 0;
  
  			/*
  			 * Typically, it is not useful to look for matches within join
  			 * RTEs; they effectively duplicate other RTEs for our purposes,
  			 * and if a match is chosen from a join RTE, an unhelpful alias is
  			 * displayed in the final diagnostic message.
  			 */
  			if (rte->rtekind == RTE_JOIN)
  				continue;
  
  			/*
  			 * If the user didn't specify an alias, then matches against one
  			 * RTE are as good as another.  But if the user did specify an
  			 * alias, then we want at least a fuzzy - and preferably an exact
  			 * - match for the range table entry.
  			 */
  			if (alias != NULL)
  				fuzzy_rte_penalty =
  					varstr_levenshtein_less_equal(alias, strlen(alias),
  												  rte->eref->aliasname,
  												  strlen(rte->eref->aliasname),
  												  1, 1, 1,
  												  MAX_FUZZY_DISTANCE + 1,
  												  true);
  
  			/*
  			 * Scan for a matching column; if we find an exact match, we're
  			 * done.  Otherwise, update fuzzystate.
  			 */
  			if (scanRTEForColumn(orig_pstate, rte, colname, location,
  								 fuzzy_rte_penalty, fuzzystate)
  				&& fuzzy_rte_penalty == 0)
  			{
  				fuzzystate->rfirst = rte;
  				fuzzystate->first = InvalidAttrNumber;
  				fuzzystate->rsecond = NULL;
  				fuzzystate->second = InvalidAttrNumber;
  				return fuzzystate;
  			}
  		}
  
  		pstate = pstate->parentParseState;
  	}
  
  	return fuzzystate;
  }
  
  /*
   * markRTEForSelectPriv
   *	   Mark the specified column of an RTE as requiring SELECT privilege
   *
   * col == InvalidAttrNumber means a "whole row" reference
   *
   * The caller should pass the actual RTE if it has it handy; otherwise pass
   * NULL, and we'll look it up here.  (This uglification of the API is
   * worthwhile because nearly all external callers have the RTE at hand.)
   */
  static void
  markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
  					 int rtindex, AttrNumber col)
  {
  	if (rte == NULL)
  		rte = rt_fetch(rtindex, pstate->p_rtable);
  
  	if (rte->rtekind == RTE_RELATION)
  	{
  		/* Make sure the rel as a whole is marked for SELECT access */
  		rte->requiredPerms |= ACL_SELECT;
  		/* Must offset the attnum to fit in a bitmapset */
  		rte->selectedCols = bms_add_member(rte->selectedCols,
  										   col - FirstLowInvalidHeapAttributeNumber);
  	}
  	else if (rte->rtekind == RTE_JOIN)
  	{
  		if (col == InvalidAttrNumber)
  		{
  			/*
  			 * A whole-row reference to a join has to be treated as whole-row
  			 * references to the two inputs.
  			 */
  			JoinExpr   *j;
  
  			if (rtindex > 0 && rtindex <= list_length(pstate->p_joinexprs))
  				j = list_nth_node(JoinExpr, pstate->p_joinexprs, rtindex - 1);
  			else
  				j = NULL;
  			if (j == NULL)
  				elog(ERROR, "could not find JoinExpr for whole-row reference");
  
  			/* Note: we can't see FromExpr here */
  			if (IsA(j->larg, RangeTblRef))
  			{
  				int			varno = ((RangeTblRef *) j->larg)->rtindex;
  
  				markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
  			}
  			else if (IsA(j->larg, JoinExpr))
  			{
  				int			varno = ((JoinExpr *) j->larg)->rtindex;
  
  				markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
  			}
  			else
  				elog(ERROR, "unrecognized node type: %d",
  					 (int) nodeTag(j->larg));
  			if (IsA(j->rarg, RangeTblRef))
  			{
  				int			varno = ((RangeTblRef *) j->rarg)->rtindex;
  
  				markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
  			}
  			else if (IsA(j->rarg, JoinExpr))
  			{
  				int			varno = ((JoinExpr *) j->rarg)->rtindex;
  
  				markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
  			}
  			else
  				elog(ERROR, "unrecognized node type: %d",
  					 (int) nodeTag(j->rarg));
  		}
  		else
  		{
  			/*
  			 * Regular join attribute, look at the alias-variable list.
  			 *
  			 * The aliasvar could be either a Var or a COALESCE expression,
  			 * but in the latter case we should already have marked the two
  			 * referent variables as being selected, due to their use in the
  			 * JOIN clause.  So we need only be concerned with the Var case.
  			 * But we do need to drill down through implicit coercions.
  			 */
  			Var		   *aliasvar;
  
  			Assert(col > 0 && col <= list_length(rte->joinaliasvars));
  			aliasvar = (Var *) list_nth(rte->joinaliasvars, col - 1);
  			aliasvar = (Var *) strip_implicit_coercions((Node *) aliasvar);
  			if (aliasvar && IsA(aliasvar, Var))
  				markVarForSelectPriv(pstate, aliasvar, NULL);
  		}
  	}
  	/* other RTE types don't require privilege marking */
  }
  
  /*
   * markVarForSelectPriv
   *	   Mark the RTE referenced by a Var as requiring SELECT privilege
   *
   * The caller should pass the Var's referenced RTE if it has it handy
   * (nearly all do); otherwise pass NULL.
   */
  void
  markVarForSelectPriv(ParseState *pstate, Var *var, RangeTblEntry *rte)
  {
  	Index		lv;
  
  	Assert(IsA(var, Var));
  	/* Find the appropriate pstate if it's an uplevel Var */
  	for (lv = 0; lv < var->varlevelsup; lv++)
  		pstate = pstate->parentParseState;
  	markRTEForSelectPriv(pstate, rte, var->varno, var->varattno);
  }
  
  /*
   * buildRelationAliases
   *		Construct the eref column name list for a relation RTE.
   *		This code is also used for function RTEs.
   *
   * tupdesc: the physical column information
   * alias: the user-supplied alias, or NULL if none
   * eref: the eref Alias to store column names in
   *
   * eref->colnames is filled in.  Also, alias->colnames is rebuilt to insert
   * empty strings for any dropped columns, so that it will be one-to-one with
   * physical column numbers.
   *
   * It is an error for there to be more aliases present than required.
   */
  static void
  buildRelationAliases(TupleDesc tupdesc, Alias *alias, Alias *eref)
  {
  	int			maxattrs = tupdesc->natts;
  	ListCell   *aliaslc;
  	int			numaliases;
  	int			varattno;
  	int			numdropped = 0;
  
  	Assert(eref->colnames == NIL);
  
  	if (alias)
  	{
  		aliaslc = list_head(alias->colnames);
  		numaliases = list_length(alias->colnames);
  		/* We'll rebuild the alias colname list */
  		alias->colnames = NIL;
  	}
  	else
  	{
  		aliaslc = NULL;
  		numaliases = 0;
  	}
  
  	for (varattno = 0; varattno < maxattrs; varattno++)
  	{
  		Form_pg_attribute attr = TupleDescAttr(tupdesc, varattno);
  		Value	   *attrname;
  
  		if (attr->attisdropped)
  		{
  			/* Always insert an empty string for a dropped column */
  			attrname = makeString(pstrdup(""));
  			if (aliaslc)
  				alias->colnames = lappend(alias->colnames, attrname);
  			numdropped++;
  		}
  		else if (aliaslc)
  		{
  			/* Use the next user-supplied alias */
  			attrname = (Value *) lfirst(aliaslc);
  			aliaslc = lnext(aliaslc);
  			alias->colnames = lappend(alias->colnames, attrname);
  		}
  		else
  		{
  			attrname = makeString(pstrdup(NameStr(attr->attname)));
  			/* we're done with the alias if any */
  		}
  
  		eref->colnames = lappend(eref->colnames, attrname);
  	}
  
  	/* Too many user-supplied aliases? */
  	if (aliaslc)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  				 errmsg("table \"%s\" has %d columns available but %d columns specified",
  						eref->aliasname, maxattrs - numdropped, numaliases)));
  }
  
  /*
   * chooseScalarFunctionAlias
   *		Select the column alias for a function in a function RTE,
   *		when the function returns a scalar type (not composite or RECORD).
   *
   * funcexpr: transformed expression tree for the function call
   * funcname: function name (as determined by FigureColname)
   * alias: the user-supplied alias for the RTE, or NULL if none
   * nfuncs: the number of functions appearing in the function RTE
   *
   * Note that the name we choose might be overridden later, if the user-given
   * alias includes column alias names.  That's of no concern here.
   */
  static char *
  chooseScalarFunctionAlias(Node *funcexpr, char *funcname,
  						  Alias *alias, int nfuncs)
  {
  	char	   *pname;
  
  	/*
  	 * If the expression is a simple function call, and the function has a
  	 * single OUT parameter that is named, use the parameter's name.
  	 */
  	if (funcexpr && IsA(funcexpr, FuncExpr))
  	{
  		pname = get_func_result_name(((FuncExpr *) funcexpr)->funcid);
  		if (pname)
  			return pname;
  	}
  
  	/*
  	 * If there's just one function in the RTE, and the user gave an RTE alias
  	 * name, use that name.  (This makes FROM func() AS foo use "foo" as the
  	 * column name as well as the table alias.)
  	 */
  	if (nfuncs == 1 && alias)
  		return alias->aliasname;
  
  	/*
  	 * Otherwise use the function name.
  	 */
  	return funcname;
  }
  
  /*
   * Open a table during parse analysis
   *
   * This is essentially just the same as heap_openrv(), except that it caters
   * to some parser-specific error reporting needs, notably that it arranges
   * to include the RangeVar's parse location in any resulting error.
   *
   * Note: properly, lockmode should be declared LOCKMODE not int, but that
   * would require importing storage/lock.h into parse_relation.h.  Since
   * LOCKMODE is typedef'd as int anyway, that seems like overkill.
   */
  Relation
  parserOpenTable(ParseState *pstate, const RangeVar *relation, int lockmode)
  {
  	Relation	rel;
  	ParseCallbackState pcbstate;
  
  	setup_parser_errposition_callback(&pcbstate, pstate, relation->location);
  	rel = heap_openrv_extended(relation, lockmode, true);
  	if (rel == NULL)
  	{
  		if (relation->schemaname)
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_TABLE),
  					 errmsg("relation \"%s.%s\" does not exist",
  							relation->schemaname, relation->relname)));
  		else
  		{
  			/*
  			 * An unqualified name might have been meant as a reference to
  			 * some not-yet-in-scope CTE.  The bare "does not exist" message
  			 * has proven remarkably unhelpful for figuring out such problems,
  			 * so we take pains to offer a specific hint.
  			 */
  			if (isFutureCTE(pstate, relation->relname))
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_TABLE),
  						 errmsg("relation \"%s\" does not exist",
  								relation->relname),
  						 errdetail("There is a WITH item named \"%s\", but it cannot be referenced from this part of the query.",
  								   relation->relname),
  						 errhint("Use WITH RECURSIVE, or re-order the WITH items to remove forward references.")));
  			else
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_TABLE),
  						 errmsg("relation \"%s\" does not exist",
  								relation->relname)));
  		}
  	}
  	cancel_parser_errposition_callback(&pcbstate);
  	return rel;
  }
  
  /*
   * Add an entry for a relation to the pstate's range table (p_rtable).
   *
   * Note: formerly this checked for refname conflicts, but that's wrong.
   * Caller is responsible for checking for conflicts in the appropriate scope.
   */
  RangeTblEntry *
  addRangeTableEntry(ParseState *pstate,
  				   RangeVar *relation,
  				   Alias *alias,
  				   bool inh,
  				   bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	char	   *refname = alias ? alias->aliasname : relation->relname;
  	LOCKMODE	lockmode;
  	Relation	rel;
  
  	Assert(pstate != NULL);
  
  	rte->rtekind = RTE_RELATION;
  	rte->alias = alias;
  
  	/*
  	 * Identify the type of lock we'll need on this relation.  It's not the
  	 * query's target table (that case is handled elsewhere), so we need
  	 * either RowShareLock if it's locked by FOR UPDATE/SHARE, or plain
  	 * AccessShareLock otherwise.
  	 */
  	lockmode = isLockedRefname(pstate, refname) ? RowShareLock : AccessShareLock;
  
  	/*
  	 * Get the rel's OID.  This access also ensures that we have an up-to-date
  	 * relcache entry for the rel.  Since this is typically the first access
  	 * to a rel in a statement, we must open the rel with the proper lockmode.
  	 */
  	rel = parserOpenTable(pstate, relation, lockmode);
  	rte->relid = RelationGetRelid(rel);
  	rte->relkind = rel->rd_rel->relkind;
  	rte->rellockmode = lockmode;
  
  	/*
  	 * Build the list of effective column names using user-supplied aliases
  	 * and/or actual column names.
  	 */
  	rte->eref = makeAlias(refname, NIL);
  	buildRelationAliases(rel->rd_att, alias, rte->eref);
  
  	/*
  	 * Drop the rel refcount, but keep the access lock till end of transaction
  	 * so that the table can't be deleted or have its schema modified
  	 * underneath us.
  	 */
  	heap_close(rel, NoLock);
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * The initial default on access checks is always check-for-READ-access,
  	 * which is the right thing for all except target tables.
  	 */
  	rte->lateral = false;
  	rte->inh = inh;
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = ACL_SELECT;
  	rte->checkAsUser = InvalidOid;	/* not set-uid by default, either */
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a relation to the pstate's range table (p_rtable).
   *
   * This is just like addRangeTableEntry() except that it makes an RTE
   * given an already-open relation instead of a RangeVar reference.
   *
   * lockmode is the lock type required for query execution; it must be one
   * of AccessShareLock, RowShareLock, or RowExclusiveLock depending on the
   * RTE's role within the query.  The caller must hold that lock mode
   * or a stronger one.
   *
   * Note: properly, lockmode should be declared LOCKMODE not int, but that
   * would require importing storage/lock.h into parse_relation.h.  Since
   * LOCKMODE is typedef'd as int anyway, that seems like overkill.
   */
  RangeTblEntry *
  addRangeTableEntryForRelation(ParseState *pstate,
  							  Relation rel,
  							  int lockmode,
  							  Alias *alias,
  							  bool inh,
  							  bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	char	   *refname = alias ? alias->aliasname : RelationGetRelationName(rel);
  
  	Assert(pstate != NULL);
  
  	Assert(lockmode == AccessShareLock ||
  		   lockmode == RowShareLock ||
  		   lockmode == RowExclusiveLock);
  	Assert(CheckRelationLockedByMe(rel, lockmode, true));
  
  	rte->rtekind = RTE_RELATION;
  	rte->alias = alias;
  	rte->relid = RelationGetRelid(rel);
  	rte->relkind = rel->rd_rel->relkind;
  	rte->rellockmode = lockmode;
  
  	/*
  	 * Build the list of effective column names using user-supplied aliases
  	 * and/or actual column names.
  	 */
  	rte->eref = makeAlias(refname, NIL);
  	buildRelationAliases(rel->rd_att, alias, rte->eref);
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * The initial default on access checks is always check-for-READ-access,
  	 * which is the right thing for all except target tables.
  	 */
  	rte->lateral = false;
  	rte->inh = inh;
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = ACL_SELECT;
  	rte->checkAsUser = InvalidOid;	/* not set-uid by default, either */
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a subquery to the pstate's range table (p_rtable).
   *
   * This is just like addRangeTableEntry() except that it makes a subquery RTE.
   * Note that an alias clause *must* be supplied.
   */
  RangeTblEntry *
  addRangeTableEntryForSubquery(ParseState *pstate,
  							  Query *subquery,
  							  Alias *alias,
  							  bool lateral,
  							  bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	char	   *refname = alias->aliasname;
  	Alias	   *eref;
  	int			numaliases;
  	int			varattno;
  	ListCell   *tlistitem;
  
  	Assert(pstate != NULL);
  
  	rte->rtekind = RTE_SUBQUERY;
  	rte->subquery = subquery;
  	rte->alias = alias;
  
  	eref = copyObject(alias);
  	numaliases = list_length(eref->colnames);
  
  	/* fill in any unspecified alias columns */
  	varattno = 0;
  	foreach(tlistitem, subquery->targetList)
  	{
  		TargetEntry *te = (TargetEntry *) lfirst(tlistitem);
  
  		if (te->resjunk)
  			continue;
  		varattno++;
  		Assert(varattno == te->resno);
  		if (varattno > numaliases)
  		{
  			char	   *attrname;
  
  			attrname = pstrdup(te->resname);
  			eref->colnames = lappend(eref->colnames, makeString(attrname));
  		}
  	}
  	if (varattno < numaliases)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  				 errmsg("table \"%s\" has %d columns available but %d columns specified",
  						refname, varattno, numaliases)));
  
  	rte->eref = eref;
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * Subqueries are never checked for access rights.
  	 */
  	rte->lateral = lateral;
  	rte->inh = false;			/* never true for subqueries */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a function (or functions) to the pstate's range table
   * (p_rtable).
   *
   * This is just like addRangeTableEntry() except that it makes a function RTE.
   */
  RangeTblEntry *
  addRangeTableEntryForFunction(ParseState *pstate,
  							  List *funcnames,
  							  List *funcexprs,
  							  List *coldeflists,
  							  RangeFunction *rangefunc,
  							  bool lateral,
  							  bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	Alias	   *alias = rangefunc->alias;
  	Alias	   *eref;
  	char	   *aliasname;
  	int			nfuncs = list_length(funcexprs);
  	TupleDesc  *functupdescs;
  	TupleDesc	tupdesc;
  	ListCell   *lc1,
  			   *lc2,
  			   *lc3;
  	int			i;
  	int			j;
  	int			funcno;
  	int			natts,
  				totalatts;
  
  	Assert(pstate != NULL);
  
  	rte->rtekind = RTE_FUNCTION;
  	rte->relid = InvalidOid;
  	rte->subquery = NULL;
  	rte->functions = NIL;		/* we'll fill this list below */
  	rte->funcordinality = rangefunc->ordinality;
  	rte->alias = alias;
  
  	/*
  	 * Choose the RTE alias name.  We default to using the first function's
  	 * name even when there's more than one; which is maybe arguable but beats
  	 * using something constant like "table".
  	 */
  	if (alias)
  		aliasname = alias->aliasname;
  	else
  		aliasname = linitial(funcnames);
  
  	eref = makeAlias(aliasname, NIL);
  	rte->eref = eref;
  
  	/* Process each function ... */
  	functupdescs = (TupleDesc *) palloc(nfuncs * sizeof(TupleDesc));
  
  	totalatts = 0;
  	funcno = 0;
  	forthree(lc1, funcexprs, lc2, funcnames, lc3, coldeflists)
  	{
  		Node	   *funcexpr = (Node *) lfirst(lc1);
  		char	   *funcname = (char *) lfirst(lc2);
  		List	   *coldeflist = (List *) lfirst(lc3);
  		RangeTblFunction *rtfunc = makeNode(RangeTblFunction);
  		TypeFuncClass functypclass;
  		Oid			funcrettype;
  
  		/* Initialize RangeTblFunction node */
  		rtfunc->funcexpr = funcexpr;
  		rtfunc->funccolnames = NIL;
  		rtfunc->funccoltypes = NIL;
  		rtfunc->funccoltypmods = NIL;
  		rtfunc->funccolcollations = NIL;
  		rtfunc->funcparams = NULL;	/* not set until planning */
  
  		/*
  		 * Now determine if the function returns a simple or composite type.
  		 */
  		functypclass = get_expr_result_type(funcexpr,
  											&funcrettype,
  											&tupdesc);
  
  		/*
  		 * A coldeflist is required if the function returns RECORD and hasn't
  		 * got a predetermined record type, and is prohibited otherwise.
  		 */
  		if (coldeflist != NIL)
  		{
  			if (functypclass != TYPEFUNC_RECORD)
  				ereport(ERROR,
  						(errcode(ERRCODE_SYNTAX_ERROR),
  						 errmsg("a column definition list is only allowed for functions returning \"record\""),
  						 parser_errposition(pstate,
  											exprLocation((Node *) coldeflist))));
  		}
  		else
  		{
  			if (functypclass == TYPEFUNC_RECORD)
  				ereport(ERROR,
  						(errcode(ERRCODE_SYNTAX_ERROR),
  						 errmsg("a column definition list is required for functions returning \"record\""),
  						 parser_errposition(pstate, exprLocation(funcexpr))));
  		}
  
  		if (functypclass == TYPEFUNC_COMPOSITE ||
  			functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
  		{
  			/* Composite data type, e.g. a table's row type */
  			Assert(tupdesc);
  		}
  		else if (functypclass == TYPEFUNC_SCALAR)
  		{
  			/* Base data type, i.e. scalar */
  			tupdesc = CreateTemplateTupleDesc(1, false);
  			TupleDescInitEntry(tupdesc,
  							   (AttrNumber) 1,
  							   chooseScalarFunctionAlias(funcexpr, funcname,
  														 alias, nfuncs),
  							   funcrettype,
  							   -1,
  							   0);
  		}
  		else if (functypclass == TYPEFUNC_RECORD)
  		{
  			ListCell   *col;
  
  			/*
  			 * Use the column definition list to construct a tupdesc and fill
  			 * in the RangeTblFunction's lists.
  			 */
  			tupdesc = CreateTemplateTupleDesc(list_length(coldeflist), false);
  			i = 1;
  			foreach(col, coldeflist)
  			{
  				ColumnDef  *n = (ColumnDef *) lfirst(col);
  				char	   *attrname;
  				Oid			attrtype;
  				int32		attrtypmod;
  				Oid			attrcollation;
  
  				attrname = n->colname;
  				if (n->typeName->setof)
  					ereport(ERROR,
  							(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
  							 errmsg("column \"%s\" cannot be declared SETOF",
  									attrname),
  							 parser_errposition(pstate, n->location)));
  				typenameTypeIdAndMod(pstate, n->typeName,
  									 &attrtype, &attrtypmod);
  				attrcollation = GetColumnDefCollation(pstate, n, attrtype);
  				TupleDescInitEntry(tupdesc,
  								   (AttrNumber) i,
  								   attrname,
  								   attrtype,
  								   attrtypmod,
  								   0);
  				TupleDescInitEntryCollation(tupdesc,
  											(AttrNumber) i,
  											attrcollation);
  				rtfunc->funccolnames = lappend(rtfunc->funccolnames,
  											   makeString(pstrdup(attrname)));
  				rtfunc->funccoltypes = lappend_oid(rtfunc->funccoltypes,
  												   attrtype);
  				rtfunc->funccoltypmods = lappend_int(rtfunc->funccoltypmods,
  													 attrtypmod);
  				rtfunc->funccolcollations = lappend_oid(rtfunc->funccolcollations,
  														attrcollation);
  
  				i++;
  			}
  
  			/*
  			 * Ensure that the coldeflist defines a legal set of names (no
  			 * duplicates) and datatypes (no pseudo-types, for instance).
  			 */
  			CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE, false);
  		}
  		else
  			ereport(ERROR,
  					(errcode(ERRCODE_DATATYPE_MISMATCH),
  					 errmsg("function \"%s\" in FROM has unsupported return type %s",
  							funcname, format_type_be(funcrettype)),
  					 parser_errposition(pstate, exprLocation(funcexpr))));
  
  		/* Finish off the RangeTblFunction and add it to the RTE's list */
  		rtfunc->funccolcount = tupdesc->natts;
  		rte->functions = lappend(rte->functions, rtfunc);
  
  		/* Save the tupdesc for use below */
  		functupdescs[funcno] = tupdesc;
  		totalatts += tupdesc->natts;
  		funcno++;
  	}
  
  	/*
  	 * If there's more than one function, or we want an ordinality column, we
  	 * have to produce a merged tupdesc.
  	 */
  	if (nfuncs > 1 || rangefunc->ordinality)
  	{
  		if (rangefunc->ordinality)
  			totalatts++;
  
  		/* Merge the tuple descs of each function into a composite one */
  		tupdesc = CreateTemplateTupleDesc(totalatts, false);
  		natts = 0;
  		for (i = 0; i < nfuncs; i++)
  		{
  			for (j = 1; j <= functupdescs[i]->natts; j++)
  				TupleDescCopyEntry(tupdesc, ++natts, functupdescs[i], j);
  		}
  
  		/* Add the ordinality column if needed */
  		if (rangefunc->ordinality)
  			TupleDescInitEntry(tupdesc,
  							   (AttrNumber) ++natts,
  							   "ordinality",
  							   INT8OID,
  							   -1,
  							   0);
  
  		Assert(natts == totalatts);
  	}
  	else
  	{
  		/* We can just use the single function's tupdesc as-is */
  		tupdesc = functupdescs[0];
  	}
  
  	/* Use the tupdesc while assigning column aliases for the RTE */
  	buildRelationAliases(tupdesc, alias, eref);
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * Functions are never checked for access rights (at least, not by the RTE
  	 * permissions mechanism).
  	 */
  	rte->lateral = lateral;
  	rte->inh = false;			/* never true for functions */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a table function to the pstate's range table (p_rtable).
   *
   * This is much like addRangeTableEntry() except that it makes a tablefunc RTE.
   */
  RangeTblEntry *
  addRangeTableEntryForTableFunc(ParseState *pstate,
  							   TableFunc *tf,
  							   Alias *alias,
  							   bool lateral,
  							   bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	char	   *refname = alias ? alias->aliasname : pstrdup("xmltable");
  	Alias	   *eref;
  	int			numaliases;
  
  	Assert(pstate != NULL);
  
  	rte->rtekind = RTE_TABLEFUNC;
  	rte->relid = InvalidOid;
  	rte->subquery = NULL;
  	rte->tablefunc = tf;
  	rte->coltypes = tf->coltypes;
  	rte->coltypmods = tf->coltypmods;
  	rte->colcollations = tf->colcollations;
  	rte->alias = alias;
  
  	eref = alias ? copyObject(alias) : makeAlias(refname, NIL);
  	numaliases = list_length(eref->colnames);
  
  	/* fill in any unspecified alias columns */
  	if (numaliases < list_length(tf->colnames))
  		eref->colnames = list_concat(eref->colnames,
  									 list_copy_tail(tf->colnames, numaliases));
  
  	rte->eref = eref;
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * Tablefuncs are never checked for access rights (at least, not by the
  	 * RTE permissions mechanism).
  	 */
  	rte->lateral = lateral;
  	rte->inh = false;			/* never true for tablefunc RTEs */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a VALUES list to the pstate's range table (p_rtable).
   *
   * This is much like addRangeTableEntry() except that it makes a values RTE.
   */
  RangeTblEntry *
  addRangeTableEntryForValues(ParseState *pstate,
  							List *exprs,
  							List *coltypes,
  							List *coltypmods,
  							List *colcollations,
  							Alias *alias,
  							bool lateral,
  							bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	char	   *refname = alias ? alias->aliasname : pstrdup("*VALUES*");
  	Alias	   *eref;
  	int			numaliases;
  	int			numcolumns;
  
  	Assert(pstate != NULL);
  
  	rte->rtekind = RTE_VALUES;
  	rte->relid = InvalidOid;
  	rte->subquery = NULL;
  	rte->values_lists = exprs;
  	rte->coltypes = coltypes;
  	rte->coltypmods = coltypmods;
  	rte->colcollations = colcollations;
  	rte->alias = alias;
  
  	eref = alias ? copyObject(alias) : makeAlias(refname, NIL);
  
  	/* fill in any unspecified alias columns */
  	numcolumns = list_length((List *) linitial(exprs));
  	numaliases = list_length(eref->colnames);
  	while (numaliases < numcolumns)
  	{
  		char		attrname[64];
  
  		numaliases++;
  		snprintf(attrname, sizeof(attrname), "column%d", numaliases);
  		eref->colnames = lappend(eref->colnames,
  								 makeString(pstrdup(attrname)));
  	}
  	if (numcolumns < numaliases)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  				 errmsg("VALUES lists \"%s\" have %d columns available but %d columns specified",
  						refname, numcolumns, numaliases)));
  
  	rte->eref = eref;
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * Subqueries are never checked for access rights.
  	 */
  	rte->lateral = lateral;
  	rte->inh = false;			/* never true for values RTEs */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a join to the pstate's range table (p_rtable).
   *
   * This is much like addRangeTableEntry() except that it makes a join RTE.
   */
  RangeTblEntry *
  addRangeTableEntryForJoin(ParseState *pstate,
  						  List *colnames,
  						  JoinType jointype,
  						  List *aliasvars,
  						  Alias *alias,
  						  bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	Alias	   *eref;
  	int			numaliases;
  
  	Assert(pstate != NULL);
  
  	/*
  	 * Fail if join has too many columns --- we must be able to reference any
  	 * of the columns with an AttrNumber.
  	 */
  	if (list_length(aliasvars) > MaxAttrNumber)
  		ereport(ERROR,
  				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
  				 errmsg("joins can have at most %d columns",
  						MaxAttrNumber)));
  
  	rte->rtekind = RTE_JOIN;
  	rte->relid = InvalidOid;
  	rte->subquery = NULL;
  	rte->jointype = jointype;
  	rte->joinaliasvars = aliasvars;
  	rte->alias = alias;
  
  	eref = alias ? copyObject(alias) : makeAlias("unnamed_join", NIL);
  	numaliases = list_length(eref->colnames);
  
  	/* fill in any unspecified alias columns */
  	if (numaliases < list_length(colnames))
  		eref->colnames = list_concat(eref->colnames,
  									 list_copy_tail(colnames, numaliases));
  
  	rte->eref = eref;
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * Joins are never checked for access rights.
  	 */
  	rte->lateral = false;
  	rte->inh = false;			/* never true for joins */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for a CTE reference to the pstate's range table (p_rtable).
   *
   * This is much like addRangeTableEntry() except that it makes a CTE RTE.
   */
  RangeTblEntry *
  addRangeTableEntryForCTE(ParseState *pstate,
  						 CommonTableExpr *cte,
  						 Index levelsup,
  						 RangeVar *rv,
  						 bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	Alias	   *alias = rv->alias;
  	char	   *refname = alias ? alias->aliasname : cte->ctename;
  	Alias	   *eref;
  	int			numaliases;
  	int			varattno;
  	ListCell   *lc;
  
  	Assert(pstate != NULL);
  
  	rte->rtekind = RTE_CTE;
  	rte->ctename = cte->ctename;
  	rte->ctelevelsup = levelsup;
  
  	/* Self-reference if and only if CTE's parse analysis isn't completed */
  	rte->self_reference = !IsA(cte->ctequery, Query);
  	Assert(cte->cterecursive || !rte->self_reference);
  	/* Bump the CTE's refcount if this isn't a self-reference */
  	if (!rte->self_reference)
  		cte->cterefcount++;
  
  	/*
  	 * We throw error if the CTE is INSERT/UPDATE/DELETE without RETURNING.
  	 * This won't get checked in case of a self-reference, but that's OK
  	 * because data-modifying CTEs aren't allowed to be recursive anyhow.
  	 */
  	if (IsA(cte->ctequery, Query))
  	{
  		Query	   *ctequery = (Query *) cte->ctequery;
  
  		if (ctequery->commandType != CMD_SELECT &&
  			ctequery->returningList == NIL)
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("WITH query \"%s\" does not have a RETURNING clause",
  							cte->ctename),
  					 parser_errposition(pstate, rv->location)));
  	}
  
  	rte->coltypes = cte->ctecoltypes;
  	rte->coltypmods = cte->ctecoltypmods;
  	rte->colcollations = cte->ctecolcollations;
  
  	rte->alias = alias;
  	if (alias)
  		eref = copyObject(alias);
  	else
  		eref = makeAlias(refname, NIL);
  	numaliases = list_length(eref->colnames);
  
  	/* fill in any unspecified alias columns */
  	varattno = 0;
  	foreach(lc, cte->ctecolnames)
  	{
  		varattno++;
  		if (varattno > numaliases)
  			eref->colnames = lappend(eref->colnames, lfirst(lc));
  	}
  	if (varattno < numaliases)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
  				 errmsg("table \"%s\" has %d columns available but %d columns specified",
  						refname, varattno, numaliases)));
  
  	rte->eref = eref;
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * Subqueries are never checked for access rights.
  	 */
  	rte->lateral = false;
  	rte->inh = false;			/* never true for subqueries */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  	rte->insertedCols = NULL;
  	rte->updatedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  /*
   * Add an entry for an ephemeral named relation reference to the pstate's
   * range table (p_rtable).
   *
   * It is expected that the RangeVar, which up until now is only known to be an
   * ephemeral named relation, will (in conjunction with the QueryEnvironment in
   * the ParseState), create a RangeTblEntry for a specific *kind* of ephemeral
   * named relation, based on enrtype.
   *
   * This is much like addRangeTableEntry() except that it makes an RTE for an
   * ephemeral named relation.
   */
  RangeTblEntry *
  addRangeTableEntryForENR(ParseState *pstate,
  						 RangeVar *rv,
  						 bool inFromCl)
  {
  	RangeTblEntry *rte = makeNode(RangeTblEntry);
  	Alias	   *alias = rv->alias;
  	char	   *refname = alias ? alias->aliasname : rv->relname;
  	EphemeralNamedRelationMetadata enrmd;
  	TupleDesc	tupdesc;
  	int			attno;
  
  	Assert(pstate != NULL);
  	enrmd = get_visible_ENR(pstate, rv->relname);
  	Assert(enrmd != NULL);
  
  	switch (enrmd->enrtype)
  	{
  		case ENR_NAMED_TUPLESTORE:
  			rte->rtekind = RTE_NAMEDTUPLESTORE;
  			break;
  
  		default:
  			elog(ERROR, "unexpected enrtype: %d", enrmd->enrtype);
  			return NULL;		/* for fussy compilers */
  	}
  
  	/*
  	 * Record dependency on a relation.  This allows plans to be invalidated
  	 * if they access transition tables linked to a table that is altered.
  	 */
  	rte->relid = enrmd->reliddesc;
  
  	/*
  	 * Build the list of effective column names using user-supplied aliases
  	 * and/or actual column names.
  	 */
  	tupdesc = ENRMetadataGetTupDesc(enrmd);
  	rte->eref = makeAlias(refname, NIL);
  	buildRelationAliases(tupdesc, alias, rte->eref);
  
  	/* Record additional data for ENR, including column type info */
  	rte->enrname = enrmd->name;
  	rte->enrtuples = enrmd->enrtuples;
  	rte->coltypes = NIL;
  	rte->coltypmods = NIL;
  	rte->colcollations = NIL;
  	for (attno = 1; attno <= tupdesc->natts; ++attno)
  	{
  		Form_pg_attribute att = TupleDescAttr(tupdesc, attno - 1);
  
  		if (att->attisdropped)
  		{
  			/* Record zeroes for a dropped column */
  			rte->coltypes = lappend_oid(rte->coltypes, InvalidOid);
  			rte->coltypmods = lappend_int(rte->coltypmods, 0);
  			rte->colcollations = lappend_oid(rte->colcollations, InvalidOid);
  		}
  		else
  		{
  			/* Let's just make sure we can tell this isn't dropped */
  			if (att->atttypid == InvalidOid)
  				elog(ERROR, "atttypid is invalid for non-dropped column in \"%s\"",
  					 rv->relname);
  			rte->coltypes = lappend_oid(rte->coltypes, att->atttypid);
  			rte->coltypmods = lappend_int(rte->coltypmods, att->atttypmod);
  			rte->colcollations = lappend_oid(rte->colcollations,
  											 att->attcollation);
  		}
  	}
  
  	/*
  	 * Set flags and access permissions.
  	 *
  	 * ENRs are never checked for access rights.
  	 */
  	rte->lateral = false;
  	rte->inh = false;			/* never true for ENRs */
  	rte->inFromCl = inFromCl;
  
  	rte->requiredPerms = 0;
  	rte->checkAsUser = InvalidOid;
  	rte->selectedCols = NULL;
  
  	/*
  	 * Add completed RTE to pstate's range table list, but not to join list
  	 * nor namespace --- caller must do that if appropriate.
  	 */
  	pstate->p_rtable = lappend(pstate->p_rtable, rte);
  
  	return rte;
  }
  
  
  /*
   * Has the specified refname been selected FOR UPDATE/FOR SHARE?
   *
   * This is used when we have not yet done transformLockingClause, but need
   * to know the correct lock to take during initial opening of relations.
   *
   * Note: we pay no attention to whether it's FOR UPDATE vs FOR SHARE,
   * since the table-level lock is the same either way.
   */
  bool
  isLockedRefname(ParseState *pstate, const char *refname)
  {
  	ListCell   *l;
  
  	/*
  	 * If we are in a subquery specified as locked FOR UPDATE/SHARE from
  	 * parent level, then act as though there's a generic FOR UPDATE here.
  	 */
  	if (pstate->p_locked_from_parent)
  		return true;
  
  	foreach(l, pstate->p_locking_clause)
  	{
  		LockingClause *lc = (LockingClause *) lfirst(l);
  
  		if (lc->lockedRels == NIL)
  		{
  			/* all tables used in query */
  			return true;
  		}
  		else
  		{
  			/* just the named tables */
  			ListCell   *l2;
  
  			foreach(l2, lc->lockedRels)
  			{
  				RangeVar   *thisrel = (RangeVar *) lfirst(l2);
  
  				if (strcmp(refname, thisrel->relname) == 0)
  					return true;
  			}
  		}
  	}
  	return false;
  }
  
  /*
   * Add the given RTE as a top-level entry in the pstate's join list
   * and/or namespace list.  (We assume caller has checked for any
   * namespace conflicts.)  The RTE is always marked as unconditionally
   * visible, that is, not LATERAL-only.
   *
   * Note: some callers know that they can find the new ParseNamespaceItem
   * at the end of the pstate->p_namespace list.  This is a bit ugly but not
   * worth complicating this function's signature for.
   */
  void
  addRTEtoQuery(ParseState *pstate, RangeTblEntry *rte,
  			  bool addToJoinList,
  			  bool addToRelNameSpace, bool addToVarNameSpace)
  {
  	if (addToJoinList)
  	{
  		int			rtindex = RTERangeTablePosn(pstate, rte, NULL);
  		RangeTblRef *rtr = makeNode(RangeTblRef);
  
  		rtr->rtindex = rtindex;
  		pstate->p_joinlist = lappend(pstate->p_joinlist, rtr);
  	}
  	if (addToRelNameSpace || addToVarNameSpace)
  	{
  		ParseNamespaceItem *nsitem;
  
  		nsitem = (ParseNamespaceItem *) palloc(sizeof(ParseNamespaceItem));
  		nsitem->p_rte = rte;
  		nsitem->p_rel_visible = addToRelNameSpace;
  		nsitem->p_cols_visible = addToVarNameSpace;
  		nsitem->p_lateral_only = false;
  		nsitem->p_lateral_ok = true;
  		pstate->p_namespace = lappend(pstate->p_namespace, nsitem);
  	}
  }
  
  /*
   * expandRTE -- expand the columns of a rangetable entry
   *
   * This creates lists of an RTE's column names (aliases if provided, else
   * real names) and Vars for each column.  Only user columns are considered.
   * If include_dropped is false then dropped columns are omitted from the
   * results.  If include_dropped is true then empty strings and NULL constants
   * (not Vars!) are returned for dropped columns.
   *
   * rtindex, sublevels_up, and location are the varno, varlevelsup, and location
   * values to use in the created Vars.  Ordinarily rtindex should match the
   * actual position of the RTE in its rangetable.
   *
   * The output lists go into *colnames and *colvars.
   * If only one of the two kinds of output list is needed, pass NULL for the
   * output pointer for the unwanted one.
   */
  void
  expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
  		  int location, bool include_dropped,
  		  List **colnames, List **colvars)
  {
  	int			varattno;
  
  	if (colnames)
  		*colnames = NIL;
  	if (colvars)
  		*colvars = NIL;
  
  	switch (rte->rtekind)
  	{
  		case RTE_RELATION:
  			/* Ordinary relation RTE */
  			expandRelation(rte->relid, rte->eref,
  						   rtindex, sublevels_up, location,
  						   include_dropped, colnames, colvars);
  			break;
  		case RTE_SUBQUERY:
  			{
  				/* Subquery RTE */
  				ListCell   *aliasp_item = list_head(rte->eref->colnames);
  				ListCell   *tlistitem;
  
  				varattno = 0;
  				foreach(tlistitem, rte->subquery->targetList)
  				{
  					TargetEntry *te = (TargetEntry *) lfirst(tlistitem);
  
  					if (te->resjunk)
  						continue;
  					varattno++;
  					Assert(varattno == te->resno);
  
  					/*
  					 * In scenarios where columns have been added to a view
  					 * since the outer query was originally parsed, there can
  					 * be more items in the subquery tlist than the outer
  					 * query expects.  We should ignore such extra column(s)
  					 * --- compare the behavior for composite-returning
  					 * functions, in the RTE_FUNCTION case below.
  					 */
  					if (!aliasp_item)
  						break;
  
  					if (colnames)
  					{
  						char	   *label = strVal(lfirst(aliasp_item));
  
  						*colnames = lappend(*colnames, makeString(pstrdup(label)));
  					}
  
  					if (colvars)
  					{
  						Var		   *varnode;
  
  						varnode = makeVar(rtindex, varattno,
  										  exprType((Node *) te->expr),
  										  exprTypmod((Node *) te->expr),
  										  exprCollation((Node *) te->expr),
  										  sublevels_up);
  						varnode->location = location;
  
  						*colvars = lappend(*colvars, varnode);
  					}
  
  					aliasp_item = lnext(aliasp_item);
  				}
  			}
  			break;
  		case RTE_FUNCTION:
  			{
  				/* Function RTE */
  				int			atts_done = 0;
  				ListCell   *lc;
  
  				foreach(lc, rte->functions)
  				{
  					RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
  					TypeFuncClass functypclass;
  					Oid			funcrettype;
  					TupleDesc	tupdesc;
  
  					functypclass = get_expr_result_type(rtfunc->funcexpr,
  														&funcrettype,
  														&tupdesc);
  					if (functypclass == TYPEFUNC_COMPOSITE ||
  						functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
  					{
  						/* Composite data type, e.g. a table's row type */
  						Assert(tupdesc);
  						expandTupleDesc(tupdesc, rte->eref,
  										rtfunc->funccolcount, atts_done,
  										rtindex, sublevels_up, location,
  										include_dropped, colnames, colvars);
  					}
  					else if (functypclass == TYPEFUNC_SCALAR)
  					{
  						/* Base data type, i.e. scalar */
  						if (colnames)
  							*colnames = lappend(*colnames,
  												list_nth(rte->eref->colnames,
  														 atts_done));
  
  						if (colvars)
  						{
  							Var		   *varnode;
  
  							varnode = makeVar(rtindex, atts_done + 1,
  											  funcrettype, -1,
  											  exprCollation(rtfunc->funcexpr),
  											  sublevels_up);
  							varnode->location = location;
  
  							*colvars = lappend(*colvars, varnode);
  						}
  					}
  					else if (functypclass == TYPEFUNC_RECORD)
  					{
  						if (colnames)
  						{
  							List	   *namelist;
  
  							/* extract appropriate subset of column list */
  							namelist = list_copy_tail(rte->eref->colnames,
  													  atts_done);
  							namelist = list_truncate(namelist,
  													 rtfunc->funccolcount);
  							*colnames = list_concat(*colnames, namelist);
  						}
  
  						if (colvars)
  						{
  							ListCell   *l1;
  							ListCell   *l2;
  							ListCell   *l3;
  							int			attnum = atts_done;
  
  							forthree(l1, rtfunc->funccoltypes,
  									 l2, rtfunc->funccoltypmods,
  									 l3, rtfunc->funccolcollations)
  							{
  								Oid			attrtype = lfirst_oid(l1);
  								int32		attrtypmod = lfirst_int(l2);
  								Oid			attrcollation = lfirst_oid(l3);
  								Var		   *varnode;
  
  								attnum++;
  								varnode = makeVar(rtindex,
  												  attnum,
  												  attrtype,
  												  attrtypmod,
  												  attrcollation,
  												  sublevels_up);
  								varnode->location = location;
  								*colvars = lappend(*colvars, varnode);
  							}
  						}
  					}
  					else
  					{
  						/* addRangeTableEntryForFunction should've caught this */
  						elog(ERROR, "function in FROM has unsupported return type");
  					}
  					atts_done += rtfunc->funccolcount;
  				}
  
  				/* Append the ordinality column if any */
  				if (rte->funcordinality)
  				{
  					if (colnames)
  						*colnames = lappend(*colnames,
  											llast(rte->eref->colnames));
  
  					if (colvars)
  					{
  						Var		   *varnode = makeVar(rtindex,
  													  atts_done + 1,
  													  INT8OID,
  													  -1,
  													  InvalidOid,
  													  sublevels_up);
  
  						*colvars = lappend(*colvars, varnode);
  					}
  				}
  			}
  			break;
  		case RTE_JOIN:
  			{
  				/* Join RTE */
  				ListCell   *colname;
  				ListCell   *aliasvar;
  
  				Assert(list_length(rte->eref->colnames) == list_length(rte->joinaliasvars));
  
  				varattno = 0;
  				forboth(colname, rte->eref->colnames, aliasvar, rte->joinaliasvars)
  				{
  					Node	   *avar = (Node *) lfirst(aliasvar);
  
  					varattno++;
  
  					/*
  					 * During ordinary parsing, there will never be any
  					 * deleted columns in the join; but we have to check since
  					 * this routine is also used by the rewriter, and joins
  					 * found in stored rules might have join columns for
  					 * since-deleted columns.  This will be signaled by a null
  					 * pointer in the alias-vars list.
  					 */
  					if (avar == NULL)
  					{
  						if (include_dropped)
  						{
  							if (colnames)
  								*colnames = lappend(*colnames,
  													makeString(pstrdup("")));
  							if (colvars)
  							{
  								/*
  								 * Can't use join's column type here (it might
  								 * be dropped!); but it doesn't really matter
  								 * what type the Const claims to be.
  								 */
  								*colvars = lappend(*colvars,
  												   makeNullConst(INT4OID, -1,
  																 InvalidOid));
  							}
  						}
  						continue;
  					}
  
  					if (colnames)
  					{
  						char	   *label = strVal(lfirst(colname));
  
  						*colnames = lappend(*colnames,
  											makeString(pstrdup(label)));
  					}
  
  					if (colvars)
  					{
  						Var		   *varnode;
  
  						varnode = makeVar(rtindex, varattno,
  										  exprType(avar),
  										  exprTypmod(avar),
  										  exprCollation(avar),
  										  sublevels_up);
  						varnode->location = location;
  
  						*colvars = lappend(*colvars, varnode);
  					}
  				}
  			}
  			break;
  		case RTE_TABLEFUNC:
  		case RTE_VALUES:
  		case RTE_CTE:
  		case RTE_NAMEDTUPLESTORE:
  			{
  				/* Tablefunc, Values, CTE, or ENR RTE */
  				ListCell   *aliasp_item = list_head(rte->eref->colnames);
  				ListCell   *lct;
  				ListCell   *lcm;
  				ListCell   *lcc;
  
  				varattno = 0;
  				forthree(lct, rte->coltypes,
  						 lcm, rte->coltypmods,
  						 lcc, rte->colcollations)
  				{
  					Oid			coltype = lfirst_oid(lct);
  					int32		coltypmod = lfirst_int(lcm);
  					Oid			colcoll = lfirst_oid(lcc);
  
  					varattno++;
  
  					if (colnames)
  					{
  						/* Assume there is one alias per output column */
  						if (OidIsValid(coltype))
  						{
  							char	   *label = strVal(lfirst(aliasp_item));
  
  							*colnames = lappend(*colnames,
  												makeString(pstrdup(label)));
  						}
  						else if (include_dropped)
  							*colnames = lappend(*colnames,
  												makeString(pstrdup("")));
  
  						aliasp_item = lnext(aliasp_item);
  					}
  
  					if (colvars)
  					{
  						if (OidIsValid(coltype))
  						{
  							Var		   *varnode;
  
  							varnode = makeVar(rtindex, varattno,
  											  coltype, coltypmod, colcoll,
  											  sublevels_up);
  							varnode->location = location;
  
  							*colvars = lappend(*colvars, varnode);
  						}
  						else if (include_dropped)
  						{
  							/*
  							 * It doesn't really matter what type the Const
  							 * claims to be.
  							 */
  							*colvars = lappend(*colvars,
  											   makeNullConst(INT4OID, -1,
  															 InvalidOid));
  						}
  					}
  				}
  			}
  			break;
  		default:
  			elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
  	}
  }
  
  /*
   * expandRelation -- expandRTE subroutine
   */
  static void
  expandRelation(Oid relid, Alias *eref, int rtindex, int sublevels_up,
  			   int location, bool include_dropped,
  			   List **colnames, List **colvars)
  {
  	Relation	rel;
  
  	/* Get the tupledesc and turn it over to expandTupleDesc */
  	rel = relation_open(relid, AccessShareLock);
  	expandTupleDesc(rel->rd_att, eref, rel->rd_att->natts, 0,
  					rtindex, sublevels_up,
  					location, include_dropped,
  					colnames, colvars);
  	relation_close(rel, AccessShareLock);
  }
  
  /*
   * expandTupleDesc -- expandRTE subroutine
   *
   * Generate names and/or Vars for the first "count" attributes of the tupdesc,
   * and append them to colnames/colvars.  "offset" is added to the varattno
   * that each Var would otherwise have, and we also skip the first "offset"
   * entries in eref->colnames.  (These provisions allow use of this code for
   * an individual composite-returning function in an RTE_FUNCTION RTE.)
   */
  static void
  expandTupleDesc(TupleDesc tupdesc, Alias *eref, int count, int offset,
  				int rtindex, int sublevels_up,
  				int location, bool include_dropped,
  				List **colnames, List **colvars)
  {
  	ListCell   *aliascell = list_head(eref->colnames);
  	int			varattno;
  
  	if (colnames)
  	{
  		int			i;
  
  		for (i = 0; i < offset; i++)
  		{
  			if (aliascell)
  				aliascell = lnext(aliascell);
  		}
  	}
  
  	Assert(count <= tupdesc->natts);
  	for (varattno = 0; varattno < count; varattno++)
  	{
  		Form_pg_attribute attr = TupleDescAttr(tupdesc, varattno);
  
  		if (attr->attisdropped)
  		{
  			if (include_dropped)
  			{
  				if (colnames)
  					*colnames = lappend(*colnames, makeString(pstrdup("")));
  				if (colvars)
  				{
  					/*
  					 * can't use atttypid here, but it doesn't really matter
  					 * what type the Const claims to be.
  					 */
  					*colvars = lappend(*colvars,
  									   makeNullConst(INT4OID, -1, InvalidOid));
  				}
  			}
  			if (aliascell)
  				aliascell = lnext(aliascell);
  			continue;
  		}
  
  		if (colnames)
  		{
  			char	   *label;
  
  			if (aliascell)
  			{
  				label = strVal(lfirst(aliascell));
  				aliascell = lnext(aliascell);
  			}
  			else
  			{
  				/* If we run out of aliases, use the underlying name */
  				label = NameStr(attr->attname);
  			}
  			*colnames = lappend(*colnames, makeString(pstrdup(label)));
  		}
  
  		if (colvars)
  		{
  			Var		   *varnode;
  
  			varnode = makeVar(rtindex, varattno + offset + 1,
  							  attr->atttypid, attr->atttypmod,
  							  attr->attcollation,
  							  sublevels_up);
  			varnode->location = location;
  
  			*colvars = lappend(*colvars, varnode);
  		}
  	}
  }
  
  /*
   * expandRelAttrs -
   *	  Workhorse for "*" expansion: produce a list of targetentries
   *	  for the attributes of the RTE
   *
   * As with expandRTE, rtindex/sublevels_up determine the varno/varlevelsup
   * fields of the Vars produced, and location sets their location.
   * pstate->p_next_resno determines the resnos assigned to the TLEs.
   * The referenced columns are marked as requiring SELECT access.
   */
  List *
  expandRelAttrs(ParseState *pstate, RangeTblEntry *rte,
  			   int rtindex, int sublevels_up, int location)
  {
  	List	   *names,
  			   *vars;
  	ListCell   *name,
  			   *var;
  	List	   *te_list = NIL;
  
  	expandRTE(rte, rtindex, sublevels_up, location, false,
  			  &names, &vars);
  
  	/*
  	 * Require read access to the table.  This is normally redundant with the
  	 * markVarForSelectPriv calls below, but not if the table has zero
  	 * columns.
  	 */
  	rte->requiredPerms |= ACL_SELECT;
  
  	forboth(name, names, var, vars)
  	{
  		char	   *label = strVal(lfirst(name));
  		Var		   *varnode = (Var *) lfirst(var);
  		TargetEntry *te;
  
  		te = makeTargetEntry((Expr *) varnode,
  							 (AttrNumber) pstate->p_next_resno++,
  							 label,
  							 false);
  		te_list = lappend(te_list, te);
  
  		/* Require read access to each column */
  		markVarForSelectPriv(pstate, varnode, rte);
  	}
  
  	Assert(name == NULL && var == NULL);	/* lists not the same length? */
  
  	return te_list;
  }
  
  /*
   * get_rte_attribute_name
   *		Get an attribute name from a RangeTblEntry
   *
   * This is unlike get_attname() because we use aliases if available.
   * In particular, it will work on an RTE for a subselect or join, whereas
   * get_attname() only works on real relations.
   *
   * "*" is returned if the given attnum is InvalidAttrNumber --- this case
   * occurs when a Var represents a whole tuple of a relation.
   */
  char *
  get_rte_attribute_name(RangeTblEntry *rte, AttrNumber attnum)
  {
  	if (attnum == InvalidAttrNumber)
  		return "*";
  
  	/*
  	 * If there is a user-written column alias, use it.
  	 */
  	if (rte->alias &&
  		attnum > 0 && attnum <= list_length(rte->alias->colnames))
  		return strVal(list_nth(rte->alias->colnames, attnum - 1));
  
  	/*
  	 * If the RTE is a relation, go to the system catalogs not the
  	 * eref->colnames list.  This is a little slower but it will give the
  	 * right answer if the column has been renamed since the eref list was
  	 * built (which can easily happen for rules).
  	 */
  	if (rte->rtekind == RTE_RELATION)
  		return get_attname(rte->relid, attnum, false);
  
  	/*
  	 * Otherwise use the column name from eref.  There should always be one.
  	 */
  	if (attnum > 0 && attnum <= list_length(rte->eref->colnames))
  		return strVal(list_nth(rte->eref->colnames, attnum - 1));
  
  	/* else caller gave us a bogus attnum */
  	elog(ERROR, "invalid attnum %d for rangetable entry %s",
  		 attnum, rte->eref->aliasname);
  	return NULL;				/* keep compiler quiet */
  }
  
  /*
   * get_rte_attribute_type
   *		Get attribute type/typmod/collation information from a RangeTblEntry
   */
  void
  get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
  					   Oid *vartype, int32 *vartypmod, Oid *varcollid)
  {
  	switch (rte->rtekind)
  	{
  		case RTE_RELATION:
  			{
  				/* Plain relation RTE --- get the attribute's type info */
  				HeapTuple	tp;
  				Form_pg_attribute att_tup;
  
  				tp = SearchSysCache2(ATTNUM,
  									 ObjectIdGetDatum(rte->relid),
  									 Int16GetDatum(attnum));
  				if (!HeapTupleIsValid(tp))	/* shouldn't happen */
  					elog(ERROR, "cache lookup failed for attribute %d of relation %u",
  						 attnum, rte->relid);
  				att_tup = (Form_pg_attribute) GETSTRUCT(tp);
  
  				/*
  				 * If dropped column, pretend it ain't there.  See notes in
  				 * scanRTEForColumn.
  				 */
  				if (att_tup->attisdropped)
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("column \"%s\" of relation \"%s\" does not exist",
  									NameStr(att_tup->attname),
  									get_rel_name(rte->relid))));
  				*vartype = att_tup->atttypid;
  				*vartypmod = att_tup->atttypmod;
  				*varcollid = att_tup->attcollation;
  				ReleaseSysCache(tp);
  			}
  			break;
  		case RTE_SUBQUERY:
  			{
  				/* Subselect RTE --- get type info from subselect's tlist */
  				TargetEntry *te = get_tle_by_resno(rte->subquery->targetList,
  												   attnum);
  
  				if (te == NULL || te->resjunk)
  					elog(ERROR, "subquery %s does not have attribute %d",
  						 rte->eref->aliasname, attnum);
  				*vartype = exprType((Node *) te->expr);
  				*vartypmod = exprTypmod((Node *) te->expr);
  				*varcollid = exprCollation((Node *) te->expr);
  			}
  			break;
  		case RTE_FUNCTION:
  			{
  				/* Function RTE */
  				ListCell   *lc;
  				int			atts_done = 0;
  
  				/* Identify which function covers the requested column */
  				foreach(lc, rte->functions)
  				{
  					RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
  
  					if (attnum > atts_done &&
  						attnum <= atts_done + rtfunc->funccolcount)
  					{
  						TypeFuncClass functypclass;
  						Oid			funcrettype;
  						TupleDesc	tupdesc;
  
  						attnum -= atts_done;	/* now relative to this func */
  						functypclass = get_expr_result_type(rtfunc->funcexpr,
  															&funcrettype,
  															&tupdesc);
  
  						if (functypclass == TYPEFUNC_COMPOSITE ||
  							functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
  						{
  							/* Composite data type, e.g. a table's row type */
  							Form_pg_attribute att_tup;
  
  							Assert(tupdesc);
  							Assert(attnum <= tupdesc->natts);
  							att_tup = TupleDescAttr(tupdesc, attnum - 1);
  
  							/*
  							 * If dropped column, pretend it ain't there.  See
  							 * notes in scanRTEForColumn.
  							 */
  							if (att_tup->attisdropped)
  								ereport(ERROR,
  										(errcode(ERRCODE_UNDEFINED_COLUMN),
  										 errmsg("column \"%s\" of relation \"%s\" does not exist",
  												NameStr(att_tup->attname),
  												rte->eref->aliasname)));
  							*vartype = att_tup->atttypid;
  							*vartypmod = att_tup->atttypmod;
  							*varcollid = att_tup->attcollation;
  						}
  						else if (functypclass == TYPEFUNC_SCALAR)
  						{
  							/* Base data type, i.e. scalar */
  							*vartype = funcrettype;
  							*vartypmod = -1;
  							*varcollid = exprCollation(rtfunc->funcexpr);
  						}
  						else if (functypclass == TYPEFUNC_RECORD)
  						{
  							*vartype = list_nth_oid(rtfunc->funccoltypes,
  													attnum - 1);
  							*vartypmod = list_nth_int(rtfunc->funccoltypmods,
  													  attnum - 1);
  							*varcollid = list_nth_oid(rtfunc->funccolcollations,
  													  attnum - 1);
  						}
  						else
  						{
  							/*
  							 * addRangeTableEntryForFunction should've caught
  							 * this
  							 */
  							elog(ERROR, "function in FROM has unsupported return type");
  						}
  						return;
  					}
  					atts_done += rtfunc->funccolcount;
  				}
  
  				/* If we get here, must be looking for the ordinality column */
  				if (rte->funcordinality && attnum == atts_done + 1)
  				{
  					*vartype = INT8OID;
  					*vartypmod = -1;
  					*varcollid = InvalidOid;
  					return;
  				}
  
  				/* this probably can't happen ... */
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_COLUMN),
  						 errmsg("column %d of relation \"%s\" does not exist",
  								attnum,
  								rte->eref->aliasname)));
  			}
  			break;
  		case RTE_JOIN:
  			{
  				/*
  				 * Join RTE --- get type info from join RTE's alias variable
  				 */
  				Node	   *aliasvar;
  
  				Assert(attnum > 0 && attnum <= list_length(rte->joinaliasvars));
  				aliasvar = (Node *) list_nth(rte->joinaliasvars, attnum - 1);
  				Assert(aliasvar != NULL);
  				*vartype = exprType(aliasvar);
  				*vartypmod = exprTypmod(aliasvar);
  				*varcollid = exprCollation(aliasvar);
  			}
  			break;
  		case RTE_TABLEFUNC:
  		case RTE_VALUES:
  		case RTE_CTE:
  		case RTE_NAMEDTUPLESTORE:
  			{
  				/*
  				 * tablefunc, VALUES, CTE, or ENR RTE --- get type info from
  				 * lists in the RTE
  				 */
  				Assert(attnum > 0 && attnum <= list_length(rte->coltypes));
  				*vartype = list_nth_oid(rte->coltypes, attnum - 1);
  				*vartypmod = list_nth_int(rte->coltypmods, attnum - 1);
  				*varcollid = list_nth_oid(rte->colcollations, attnum - 1);
  
  				/* For ENR, better check for dropped column */
  				if (!OidIsValid(*vartype))
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_COLUMN),
  							 errmsg("column %d of relation \"%s\" does not exist",
  									attnum,
  									rte->eref->aliasname)));
  			}
  			break;
  		default:
  			elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
  	}
  }
  
  /*
   * get_rte_attribute_is_dropped
   *		Check whether attempted attribute ref is to a dropped column
   */
  bool
  get_rte_attribute_is_dropped(RangeTblEntry *rte, AttrNumber attnum)
  {
  	bool		result;
  
  	switch (rte->rtekind)
  	{
  		case RTE_RELATION:
  			{
  				/*
  				 * Plain relation RTE --- get the attribute's catalog entry
  				 */
  				HeapTuple	tp;
  				Form_pg_attribute att_tup;
  
  				tp = SearchSysCache2(ATTNUM,
  									 ObjectIdGetDatum(rte->relid),
  									 Int16GetDatum(attnum));
  				if (!HeapTupleIsValid(tp))	/* shouldn't happen */
  					elog(ERROR, "cache lookup failed for attribute %d of relation %u",
  						 attnum, rte->relid);
  				att_tup = (Form_pg_attribute) GETSTRUCT(tp);
  				result = att_tup->attisdropped;
  				ReleaseSysCache(tp);
  			}
  			break;
  		case RTE_SUBQUERY:
  		case RTE_TABLEFUNC:
  		case RTE_VALUES:
  		case RTE_CTE:
  
  			/*
  			 * Subselect, Table Functions, Values, CTE RTEs never have dropped
  			 * columns
  			 */
  			result = false;
  			break;
  		case RTE_NAMEDTUPLESTORE:
  			{
  				/* Check dropped-ness by testing for valid coltype */
  				if (attnum <= 0 ||
  					attnum > list_length(rte->coltypes))
  					elog(ERROR, "invalid varattno %d", attnum);
  				result = !OidIsValid((list_nth_oid(rte->coltypes, attnum - 1)));
  			}
  			break;
  		case RTE_JOIN:
  			{
  				/*
  				 * A join RTE would not have dropped columns when constructed,
  				 * but one in a stored rule might contain columns that were
  				 * dropped from the underlying tables, if said columns are
  				 * nowhere explicitly referenced in the rule.  This will be
  				 * signaled to us by a null pointer in the joinaliasvars list.
  				 */
  				Var		   *aliasvar;
  
  				if (attnum <= 0 ||
  					attnum > list_length(rte->joinaliasvars))
  					elog(ERROR, "invalid varattno %d", attnum);
  				aliasvar = (Var *) list_nth(rte->joinaliasvars, attnum - 1);
  
  				result = (aliasvar == NULL);
  			}
  			break;
  		case RTE_FUNCTION:
  			{
  				/* Function RTE */
  				ListCell   *lc;
  				int			atts_done = 0;
  
  				/*
  				 * Dropped attributes are only possible with functions that
  				 * return named composite types.  In such a case we have to
  				 * look up the result type to see if it currently has this
  				 * column dropped.  So first, loop over the funcs until we
  				 * find the one that covers the requested column.
  				 */
  				foreach(lc, rte->functions)
  				{
  					RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
  
  					if (attnum > atts_done &&
  						attnum <= atts_done + rtfunc->funccolcount)
  					{
  						TupleDesc	tupdesc;
  
  						tupdesc = get_expr_result_tupdesc(rtfunc->funcexpr,
  														  true);
  						if (tupdesc)
  						{
  							/* Composite data type, e.g. a table's row type */
  							Form_pg_attribute att_tup;
  
  							Assert(tupdesc);
  							Assert(attnum - atts_done <= tupdesc->natts);
  							att_tup = TupleDescAttr(tupdesc,
  													attnum - atts_done - 1);
  							return att_tup->attisdropped;
  						}
  						/* Otherwise, it can't have any dropped columns */
  						return false;
  					}
  					atts_done += rtfunc->funccolcount;
  				}
  
  				/* If we get here, must be looking for the ordinality column */
  				if (rte->funcordinality && attnum == atts_done + 1)
  					return false;
  
  				/* this probably can't happen ... */
  				ereport(ERROR,
  						(errcode(ERRCODE_UNDEFINED_COLUMN),
  						 errmsg("column %d of relation \"%s\" does not exist",
  								attnum,
  								rte->eref->aliasname)));
  				result = false; /* keep compiler quiet */
  			}
  			break;
  		default:
  			elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
  			result = false;		/* keep compiler quiet */
  	}
  
  	return result;
  }
  
  /*
   * Given a targetlist and a resno, return the matching TargetEntry
   *
   * Returns NULL if resno is not present in list.
   *
   * Note: we need to search, rather than just indexing with list_nth(),
   * because not all tlists are sorted by resno.
   */
  TargetEntry *
  get_tle_by_resno(List *tlist, AttrNumber resno)
  {
  	ListCell   *l;
  
  	foreach(l, tlist)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(l);
  
  		if (tle->resno == resno)
  			return tle;
  	}
  	return NULL;
  }
  
  /*
   * Given a Query and rangetable index, return relation's RowMarkClause if any
   *
   * Returns NULL if relation is not selected FOR UPDATE/SHARE
   */
  RowMarkClause *
  get_parse_rowmark(Query *qry, Index rtindex)
  {
  	ListCell   *l;
  
  	foreach(l, qry->rowMarks)
  	{
  		RowMarkClause *rc = (RowMarkClause *) lfirst(l);
  
  		if (rc->rti == rtindex)
  			return rc;
  	}
  	return NULL;
  }
  
  /*
   *	given relation and att name, return attnum of variable
   *
   *	Returns InvalidAttrNumber if the attr doesn't exist (or is dropped).
   *
   *	This should only be used if the relation is already
   *	heap_open()'ed.  Use the cache version get_attnum()
   *	for access to non-opened relations.
   */
  int
  attnameAttNum(Relation rd, const char *attname, bool sysColOK)
  {
  	int			i;
  
  	for (i = 0; i < RelationGetNumberOfAttributes(rd); i++)
  	{
  		Form_pg_attribute att = TupleDescAttr(rd->rd_att, i);
  
  		if (namestrcmp(&(att->attname), attname) == 0 && !att->attisdropped)
  			return i + 1;
  	}
  
  	if (sysColOK)
  	{
  		if ((i = specialAttNum(attname)) != InvalidAttrNumber)
  		{
  			if (i != ObjectIdAttributeNumber || rd->rd_rel->relhasoids)
  				return i;
  		}
  	}
  
  	/* on failure */
  	return InvalidAttrNumber;
  }
  
  /* specialAttNum()
   *
   * Check attribute name to see if it is "special", e.g. "oid".
   * - thomas 2000-02-07
   *
   * Note: this only discovers whether the name could be a system attribute.
   * Caller needs to verify that it really is an attribute of the rel,
   * at least in the case of "oid", which is now optional.
   */
  static int
  specialAttNum(const char *attname)
  {
  	const FormData_pg_attribute *sysatt;
  
  	sysatt = SystemAttributeByName(attname,
  								   true /* "oid" will be accepted */ );
  	if (sysatt != NULL)
  		return sysatt->attnum;
  	return InvalidAttrNumber;
  }
  
  
  /*
   * given attribute id, return name of that attribute
   *
   *	This should only be used if the relation is already
   *	heap_open()'ed.  Use the cache version get_atttype()
   *	for access to non-opened relations.
   */
  const NameData *
  attnumAttName(Relation rd, int attid)
  {
  	if (attid <= 0)
  	{
  		const FormData_pg_attribute *sysatt;
  
  		sysatt = SystemAttributeDefinition(attid, rd->rd_rel->relhasoids);
  		return &sysatt->attname;
  	}
  	if (attid > rd->rd_att->natts)
  		elog(ERROR, "invalid attribute number %d", attid);
  	return &TupleDescAttr(rd->rd_att, attid - 1)->attname;
  }
  
  /*
   * given attribute id, return type of that attribute
   *
   *	This should only be used if the relation is already
   *	heap_open()'ed.  Use the cache version get_atttype()
   *	for access to non-opened relations.
   */
  Oid
  attnumTypeId(Relation rd, int attid)
  {
  	if (attid <= 0)
  	{
  		const FormData_pg_attribute *sysatt;
  
  		sysatt = SystemAttributeDefinition(attid, rd->rd_rel->relhasoids);
  		return sysatt->atttypid;
  	}
  	if (attid > rd->rd_att->natts)
  		elog(ERROR, "invalid attribute number %d", attid);
  	return TupleDescAttr(rd->rd_att, attid - 1)->atttypid;
  }
  
  /*
   * given attribute id, return collation of that attribute
   *
   *	This should only be used if the relation is already heap_open()'ed.
   */
  Oid
  attnumCollationId(Relation rd, int attid)
  {
  	if (attid <= 0)
  	{
  		/* All system attributes are of noncollatable types. */
  		return InvalidOid;
  	}
  	if (attid > rd->rd_att->natts)
  		elog(ERROR, "invalid attribute number %d", attid);
  	return TupleDescAttr(rd->rd_att, attid - 1)->attcollation;
  }
  
  /*
   * Generate a suitable error about a missing RTE.
   *
   * Since this is a very common type of error, we work rather hard to
   * produce a helpful message.
   */
  void
  errorMissingRTE(ParseState *pstate, RangeVar *relation)
  {
  	RangeTblEntry *rte;
  	int			sublevels_up;
  	const char *badAlias = NULL;
  
  	/*
  	 * Check to see if there are any potential matches in the query's
  	 * rangetable.  (Note: cases involving a bad schema name in the RangeVar
  	 * will throw error immediately here.  That seems OK.)
  	 */
  	rte = searchRangeTableForRel(pstate, relation);
  
  	/*
  	 * If we found a match that has an alias and the alias is visible in the
  	 * namespace, then the problem is probably use of the relation's real name
  	 * instead of its alias, ie "SELECT foo.* FROM foo f". This mistake is
  	 * common enough to justify a specific hint.
  	 *
  	 * If we found a match that doesn't meet those criteria, assume the
  	 * problem is illegal use of a relation outside its scope, as in the
  	 * MySQL-ism "SELECT ... FROM a, b LEFT JOIN c ON (a.x = c.y)".
  	 */
  	if (rte && rte->alias &&
  		strcmp(rte->eref->aliasname, relation->relname) != 0 &&
  		refnameRangeTblEntry(pstate, NULL, rte->eref->aliasname,
  							 relation->location,
  							 &sublevels_up) == rte)
  		badAlias = rte->eref->aliasname;
  
  	if (rte)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_TABLE),
  				 errmsg("invalid reference to FROM-clause entry for table \"%s\"",
  						relation->relname),
  				 (badAlias ?
  				  errhint("Perhaps you meant to reference the table alias \"%s\".",
  						  badAlias) :
  				  errhint("There is an entry for table \"%s\", but it cannot be referenced from this part of the query.",
  						  rte->eref->aliasname)),
  				 parser_errposition(pstate, relation->location)));
  	else
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_TABLE),
  				 errmsg("missing FROM-clause entry for table \"%s\"",
  						relation->relname),
  				 parser_errposition(pstate, relation->location)));
  }
  
  /*
   * Generate a suitable error about a missing column.
   *
   * Since this is a very common type of error, we work rather hard to
   * produce a helpful message.
   */
  void
  errorMissingColumn(ParseState *pstate,
  				   const char *relname, const char *colname, int location)
  {
  	FuzzyAttrMatchState *state;
  	char	   *closestfirst = NULL;
  
  	/*
  	 * Search the entire rtable looking for possible matches.  If we find one,
  	 * emit a hint about it.
  	 *
  	 * TODO: improve this code (and also errorMissingRTE) to mention using
  	 * LATERAL if appropriate.
  	 */
  	state = searchRangeTableForCol(pstate, relname, colname, location);
  
  	/*
  	 * Extract closest col string for best match, if any.
  	 *
  	 * Infer an exact match referenced despite not being visible from the fact
  	 * that an attribute number was not present in state passed back -- this
  	 * is what is reported when !closestfirst.  There might also be an exact
  	 * match that was qualified with an incorrect alias, in which case
  	 * closestfirst will be set (so hint is the same as generic fuzzy case).
  	 */
  	if (state->rfirst && AttributeNumberIsValid(state->first))
  		closestfirst = strVal(list_nth(state->rfirst->eref->colnames,
  									   state->first - 1));
  
  	if (!state->rsecond)
  	{
  		/*
  		 * Handle case where there is zero or one column suggestions to hint,
  		 * including exact matches referenced but not visible.
  		 */
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_COLUMN),
  				 relname ?
  				 errmsg("column %s.%s does not exist", relname, colname) :
  				 errmsg("column \"%s\" does not exist", colname),
  				 state->rfirst ? closestfirst ?
  				 errhint("Perhaps you meant to reference the column \"%s.%s\".",
  						 state->rfirst->eref->aliasname, closestfirst) :
  				 errhint("There is a column named \"%s\" in table \"%s\", but it cannot be referenced from this part of the query.",
  						 colname, state->rfirst->eref->aliasname) : 0,
  				 parser_errposition(pstate, location)));
  	}
  	else
  	{
  		/* Handle case where there are two equally useful column hints */
  		char	   *closestsecond;
  
  		closestsecond = strVal(list_nth(state->rsecond->eref->colnames,
  										state->second - 1));
  
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_COLUMN),
  				 relname ?
  				 errmsg("column %s.%s does not exist", relname, colname) :
  				 errmsg("column \"%s\" does not exist", colname),
  				 errhint("Perhaps you meant to reference the column \"%s.%s\" or the column \"%s.%s\".",
  						 state->rfirst->eref->aliasname, closestfirst,
  						 state->rsecond->eref->aliasname, closestsecond),
  				 parser_errposition(pstate, location)));
  	}
  }
  
  
  /*
   * Examine a fully-parsed query, and return true iff any relation underlying
   * the query is a temporary relation (table, view, or materialized view).
   */
  bool
  isQueryUsingTempRelation(Query *query)
  {
  	return isQueryUsingTempRelation_walker((Node *) query, NULL);
  }
  
  static bool
  isQueryUsingTempRelation_walker(Node *node, void *context)
  {
  	if (node == NULL)
  		return false;
  
  	if (IsA(node, Query))
  	{
  		Query	   *query = (Query *) node;
  		ListCell   *rtable;
  
  		foreach(rtable, query->rtable)
  		{
  			RangeTblEntry *rte = lfirst(rtable);
  
  			if (rte->rtekind == RTE_RELATION)
  			{
  				Relation	rel = heap_open(rte->relid, AccessShareLock);
  				char		relpersistence = rel->rd_rel->relpersistence;
  
  				heap_close(rel, AccessShareLock);
  				if (relpersistence == RELPERSISTENCE_TEMP)
  					return true;
  			}
  		}
  
  		return query_tree_walker(query,
  								 isQueryUsingTempRelation_walker,
  								 context,
  								 QTW_IGNORE_JOINALIASES);
  	}
  
  	return expression_tree_walker(node,
  								  isQueryUsingTempRelation_walker,
  								  context);
  }
  