From ffbeafb19a1c21245bc822f96d642fdefc510010 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 15 Apr 2001 03:14:18 +0000
Subject: [PATCH] Constant expressions that appear in ORDER BY, GROUP BY,
DISTINCT ON lists should be reverse-compiled into targetlist index numbers,
because that's the only interpretation the parser allows for a constant in
these clauses. (Ergo, the only way they could have gotten into the list in
the first place is to have come from the targetlist; so this should always
work.) Per problem report from Peter E.
---
src/backend/utils/adt/ruleutils.c | 58 +++++++++++++++++++++----------
1 file changed, 39 insertions(+), 19 deletions(-)
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index b9aab50f628..474ebdfec74 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
* back to source text
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.75 2001/03/22 06:16:18 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.76 2001/04/15 03:14:18 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@@ -120,6 +120,9 @@ static void get_basic_select_query(Query *query, deparse_context *context);
static void get_setop_query(Node *setOp, Query *query,
deparse_context *context, bool toplevel);
static bool simple_distinct(List *distinctClause, List *targetList);
+static void get_rule_sortgroupclause(SortClause *srt, List *tlist,
+ bool force_colno,
+ deparse_context *context);
static void get_names_for_var(Var *var, deparse_context *context,
char **refname, char **attname);
static bool get_alias_for_case(CaseExpr *caseexpr, deparse_context *context,
@@ -925,7 +928,7 @@ static void
get_select_query_def(Query *query, deparse_context *context)
{
StringInfo buf = context->buf;
- bool shortform_orderby;
+ bool force_colno;
char *sep;
List *l;
@@ -938,12 +941,12 @@ get_select_query_def(Query *query, deparse_context *context)
{
get_setop_query(query->setOperations, query, context, true);
/* ORDER BY clauses must be simple in this case */
- shortform_orderby = true;
+ force_colno = true;
}
else
{
get_basic_select_query(query, context);
- shortform_orderby = false;
+ force_colno = false;
}
/* Add the ORDER BY clause if given */
@@ -954,16 +957,11 @@ get_select_query_def(Query *query, deparse_context *context)
foreach(l, query->sortClause)
{
SortClause *srt = (SortClause *) lfirst(l);
- TargetEntry *sorttle;
char *opname;
- sorttle = get_sortgroupclause_tle(srt,
- query->targetList);
appendStringInfo(buf, sep);
- if (shortform_orderby)
- appendStringInfo(buf, "%d", sorttle->resdom->resno);
- else
- get_rule_expr(sorttle->expr, context);
+ get_rule_sortgroupclause(srt, query->targetList,
+ force_colno, context);
opname = get_opname(srt->sortop);
if (strcmp(opname, "<") != 0)
{
@@ -1017,12 +1015,10 @@ get_basic_select_query(Query *query, deparse_context *context)
foreach(l, query->distinctClause)
{
SortClause *srt = (SortClause *) lfirst(l);
- Node *sortexpr;
- sortexpr = get_sortgroupclause_expr(srt,
- query->targetList);
appendStringInfo(buf, sep);
- get_rule_expr(sortexpr, context);
+ get_rule_sortgroupclause(srt, query->targetList,
+ false, context);
sep = ", ";
}
appendStringInfo(buf, ")");
@@ -1082,12 +1078,10 @@ get_basic_select_query(Query *query, deparse_context *context)
foreach(l, query->groupClause)
{
GroupClause *grp = (GroupClause *) lfirst(l);
- Node *groupexpr;
- groupexpr = get_sortgroupclause_expr(grp,
- query->targetList);
appendStringInfo(buf, sep);
- get_rule_expr(groupexpr, context);
+ get_rule_sortgroupclause(grp, query->targetList,
+ false, context);
sep = ", ";
}
}
@@ -1182,6 +1176,32 @@ simple_distinct(List *distinctClause, List *targetList)
return true;
}
+/*
+ * Display a sort/group clause.
+ */
+static void
+get_rule_sortgroupclause(SortClause *srt, List *tlist, bool force_colno,
+ deparse_context *context)
+{
+ StringInfo buf = context->buf;
+ TargetEntry *tle;
+ Node *expr;
+
+ tle = get_sortgroupclause_tle(srt, tlist);
+ expr = tle->expr;
+ /*
+ * Use column-number form if requested by caller or if expression is a
+ * constant --- a constant is ambiguous (and will be misinterpreted
+ * by findTargetlistEntry()) if we dump it explicitly.
+ */
+ if (force_colno || (expr && IsA(expr, Const)))
+ {
+ Assert(!tle->resdom->resjunk);
+ appendStringInfo(buf, "%d", tle->resdom->resno);
+ }
+ else
+ get_rule_expr(expr, context);
+}
/* ----------
* get_insert_query_def - Parse back an INSERT parsetree
--
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