parse_relation.c

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/*-------------------------------------------------------------------------
 *
 * parse_relation.c
 *	  parser support routines dealing with relations
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.90.2.1 2004/04/18 18:13:31 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <ctype.h>

#include "access/heapam.h"
#include "access/htup.h"
#include "catalog/heap.h"
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "parser/parsetree.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "rewrite/rewriteManip.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"

/* GUC parameter */
bool		add_missing_from;

static Node *scanNameSpaceForRefname(ParseState *pstate, Node *nsnode,
						const char *refname);
static Node *scanNameSpaceForRelid(ParseState *pstate, Node *nsnode,
					  Oid relid);
static void scanNameSpaceForConflict(ParseState *pstate, Node *nsnode,
						 RangeTblEntry *rte1, const char *aliasname1);
static Node *scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte,
				 char *colname);
static bool isForUpdate(ParseState *pstate, char *refname);
static bool get_rte_attribute_is_dropped(RangeTblEntry *rte,
							 AttrNumber attnum);
static int	specialAttNum(const char *attname);
static void warnAutoRange(ParseState *pstate, RangeVar *relation);


/*
 * 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 SQL92 says to do.
 */
RangeTblEntry *
refnameRangeTblEntry(ParseState *pstate,
					 const char *schemaname,
					 const char *refname,
					 int *sublevels_up)
{
	Oid			relId = InvalidOid;

	if (sublevels_up)
		*sublevels_up = 0;

	if (schemaname != NULL)
	{
		Oid			namespaceId;

		namespaceId = LookupExplicitNamespace(schemaname);
		relId = get_relname_relid(refname, namespaceId);
		if (!OidIsValid(relId))
			return NULL;
	}

	while (pstate != NULL)
	{
		Node	   *nsnode;

		if (OidIsValid(relId))
			nsnode = scanNameSpaceForRelid(pstate,
										   (Node *) pstate->p_namespace,
										   relId);
		else
			nsnode = scanNameSpaceForRefname(pstate,
											 (Node *) pstate->p_namespace,
											 refname);

		if (nsnode)
		{
			/* should get an RTE or JoinExpr */
			if (IsA(nsnode, RangeTblEntry))
				return (RangeTblEntry *) nsnode;
			Assert(IsA(nsnode, JoinExpr));
			return rt_fetch(((JoinExpr *) nsnode)->rtindex, pstate->p_rtable);
		}

		pstate = pstate->parentParseState;
		if (sublevels_up)
			(*sublevels_up)++;
		else
			break;
	}
	return NULL;
}

/*
 * Recursively search a namespace for an RTE or joinexpr matching the
 * given unqualified refname.  Return the node if a unique match, or NULL
 * if no match.  Raise error if multiple matches.
 *
 * The top level of p_namespace is a list, and we recurse into any joins
 * that are not subqueries.
 */
static Node *
scanNameSpaceForRefname(ParseState *pstate, Node *nsnode,
						const char *refname)
{
	Node	   *result = NULL;
	Node	   *newresult;

	if (nsnode == NULL)
		return NULL;
	if (IsA(nsnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) nsnode)->rtindex;
		RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);

		if (strcmp(rte->eref->aliasname, refname) == 0)
			result = (Node *) rte;
	}
	else if (IsA(nsnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) nsnode;

		if (j->alias)
		{
			if (strcmp(j->alias->aliasname, refname) == 0)
				return (Node *) j;		/* matched a join alias */

			/*
			 * Tables within an aliased join are invisible from outside
			 * the join, according to the scope rules of SQL92 (the join
			 * is considered a subquery).  So, stop here.
			 */
			return NULL;
		}
		result = scanNameSpaceForRefname(pstate, j->larg, refname);
		newresult = scanNameSpaceForRefname(pstate, j->rarg, refname);
		if (!result)
			result = newresult;
		else if (newresult)
			ereport(ERROR,
					(errcode(ERRCODE_AMBIGUOUS_ALIAS),
					 errmsg("table reference \"%s\" is ambiguous",
							refname)));
	}
	else if (IsA(nsnode, List))
	{
		List	   *l;

		foreach(l, (List *) nsnode)
		{
			newresult = scanNameSpaceForRefname(pstate, lfirst(l), refname);
			if (!result)
				result = newresult;
			else if (newresult)
				ereport(ERROR,
						(errcode(ERRCODE_AMBIGUOUS_ALIAS),
						 errmsg("table reference \"%s\" is ambiguous",
								refname)));
		}
	}
	else
		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(nsnode));
	return result;
}

/*
 * Recursively search a namespace for a relation RTE matching the
 * given relation OID.	Return the node if a unique match, or NULL
 * if no match.  Raise error if multiple matches (which shouldn't
 * happen if the namespace was checked correctly when it was created).
 *
 * The top level of p_namespace is a list, and we recurse into any joins
 * that are not subqueries.
 *
 * See the comments for refnameRangeTblEntry to understand why this
 * acts the way it does.
 */
static Node *
scanNameSpaceForRelid(ParseState *pstate, Node *nsnode, Oid relid)
{
	Node	   *result = NULL;
	Node	   *newresult;

	if (nsnode == NULL)
		return NULL;
	if (IsA(nsnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) nsnode)->rtindex;
		RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);

		/* yes, the test for alias==NULL should be there... */
		if (rte->rtekind == RTE_RELATION &&
			rte->relid == relid &&
			rte->alias == NULL)
			result = (Node *) rte;
	}
	else if (IsA(nsnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) nsnode;

		if (j->alias)
		{
			/*
			 * Tables within an aliased join are invisible from outside
			 * the join, according to the scope rules of SQL92 (the join
			 * is considered a subquery).  So, stop here.
			 */
			return NULL;
		}
		result = scanNameSpaceForRelid(pstate, j->larg, relid);
		newresult = scanNameSpaceForRelid(pstate, j->rarg, relid);
		if (!result)
			result = newresult;
		else if (newresult)
			ereport(ERROR,
					(errcode(ERRCODE_AMBIGUOUS_ALIAS),
					 errmsg("table reference %u is ambiguous",
							relid)));
	}
	else if (IsA(nsnode, List))
	{
		List	   *l;

		foreach(l, (List *) nsnode)
		{
			newresult = scanNameSpaceForRelid(pstate, lfirst(l), relid);
			if (!result)
				result = newresult;
			else if (newresult)
				ereport(ERROR,
						(errcode(ERRCODE_AMBIGUOUS_ALIAS),
						 errmsg("table reference %u is ambiguous",
								relid)));
		}
	}
	else
		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(nsnode));
	return result;
}

/*
 * Recursively check for name conflicts between two namespaces or
 * namespace subtrees.	Raise an error if any is found.
 *
 * Works by recursively scanning namespace1 for RTEs and join nodes,
 * and for each one recursively scanning namespace2 for a match.
 *
 * 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 SQL92, 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).
 */
void
checkNameSpaceConflicts(ParseState *pstate, Node *namespace1,
						Node *namespace2)
{
	if (namespace1 == NULL)
		return;
	if (IsA(namespace1, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) namespace1)->rtindex;
		RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);

		if (rte->rtekind == RTE_RELATION && rte->alias == NULL)
			scanNameSpaceForConflict(pstate, namespace2,
									 rte, rte->eref->aliasname);
		else
			scanNameSpaceForConflict(pstate, namespace2,
									 NULL, rte->eref->aliasname);
	}
	else if (IsA(namespace1, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) namespace1;

		if (j->alias)
		{
			scanNameSpaceForConflict(pstate, namespace2,
									 NULL, j->alias->aliasname);

			/*
			 * Tables within an aliased join are invisible from outside
			 * the join, according to the scope rules of SQL92 (the join
			 * is considered a subquery).  So, stop here.
			 */
			return;
		}
		checkNameSpaceConflicts(pstate, j->larg, namespace2);
		checkNameSpaceConflicts(pstate, j->rarg, namespace2);
	}
	else if (IsA(namespace1, List))
	{
		List	   *l;

		foreach(l, (List *) namespace1)
			checkNameSpaceConflicts(pstate, lfirst(l), namespace2);
	}
	else
		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(namespace1));
}

/*
 * Subroutine for checkNameSpaceConflicts: scan namespace2
 */
static void
scanNameSpaceForConflict(ParseState *pstate, Node *nsnode,
						 RangeTblEntry *rte1, const char *aliasname1)
{
	if (nsnode == NULL)
		return;
	if (IsA(nsnode, RangeTblRef))
	{
		int			varno = ((RangeTblRef *) nsnode)->rtindex;
		RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);

		if (strcmp(rte->eref->aliasname, aliasname1) != 0)
			return;				/* definitely no conflict */
		if (rte->rtekind == RTE_RELATION && rte->alias == NULL &&
			rte1 != NULL && rte->relid != rte1->relid)
			return;				/* no conflict per SQL92 rule */
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_ALIAS),
				 errmsg("table name \"%s\" specified more than once",
						aliasname1)));
	}
	else if (IsA(nsnode, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) nsnode;

		if (j->alias)
		{
			if (strcmp(j->alias->aliasname, aliasname1) == 0)
				ereport(ERROR,
						(errcode(ERRCODE_DUPLICATE_ALIAS),
					 errmsg("table name \"%s\" specified more than once",
							aliasname1)));

			/*
			 * Tables within an aliased join are invisible from outside
			 * the join, according to the scope rules of SQL92 (the join
			 * is considered a subquery).  So, stop here.
			 */
			return;
		}
		scanNameSpaceForConflict(pstate, j->larg, rte1, aliasname1);
		scanNameSpaceForConflict(pstate, j->rarg, rte1, aliasname1);
	}
	else if (IsA(nsnode, List))
	{
		List	   *l;

		foreach(l, (List *) nsnode)
			scanNameSpaceForConflict(pstate, lfirst(l), rte1, aliasname1);
	}
	else
		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(nsnode));
}

/*
 * 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;
	List	   *temp;

	if (sublevels_up)
		*sublevels_up = 0;

	while (pstate != NULL)
	{
		index = 1;
		foreach(temp, pstate->p_rtable)
		{
			if (rte == (RangeTblEntry *) lfirst(temp))
				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 */
}

/*
 * 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.
 * See comments in setTargetTable().
 *
 * NOTE: if the RTE is for a join, marking it as requiring read access does
 * nothing.  It might seem that we need to propagate the mark to all the
 * contained RTEs, but that is not necessary.  This is so because a join
 * expression can only appear in a FROM clause, and any table named in
 * FROM will be marked checkForRead from the beginning.
 */
static Node *
scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte, char *colname)
{
	Node	   *result = NULL;
	int			attnum = 0;
	List	   *c;

	/*
	 * Scan the user column names (or aliases) for a match. Complain if
	 * multiple matches.
	 *
	 * Note: because eref->colnames may include names of dropped columns, we
	 * need to check for non-droppedness before accepting a match. This
	 * takes an extra cache lookup, but we can skip the lookup most of the
	 * time by exploiting the knowledge that dropped columns are assigned
	 * dummy names starting with '.', which is an unusual choice for
	 * actual column names.
	 *
	 * Should the user try to fool us by altering pg_attribute.attname for 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.
	 */
	foreach(c, rte->eref->colnames)
	{
		attnum++;
		if (strcmp(strVal(lfirst(c)), colname) == 0)
		{
			if (colname[0] == '.' &&	/* see note above */
				get_rte_attribute_is_dropped(rte, attnum))
				continue;
			if (result)
				ereport(ERROR,
						(errcode(ERRCODE_AMBIGUOUS_COLUMN),
						 errmsg("column reference \"%s\" is ambiguous",
								colname)));
			result = (Node *) make_var(pstate, rte, attnum);
			rte->checkForRead = true;
		}
	}

	/*
	 * 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.