From fba999cb2c8aeafc113b965682bcc9f9ce081c88 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 18 Jul 2010 19:37:49 +0000
Subject: [PATCH] Allow ORDER BY/GROUP BY/etc items to match targetlist items
regardless of any implicit casting previously applied to the targetlist item.
This is reasonable because the implicit cast, by definition, wasn't written
by the user; so we are preserving the expected behavior that ORDER BY items
match textually equivalent tlist items. The case never arose before because
there couldn't be any implicit casting of a top-level SELECT item before we
process ORDER BY etc. But now it can arise in the context of aggregates
containing ORDER BY clauses, since the "targetlist" is the already-casted
list of arguments for the aggregate. The net effect is that the datatype
used for ORDER BY/DISTINCT purposes is the aggregate's declared input type,
not that of the original input column; which is a bit debatable but not
horrendous, and to do otherwise would require major rework that doesn't seem
justified.
Per bug #5564 from Daniel Grace. Back-patch to 9.0 where aggregate ORDER BY
was implemented.
---
src/backend/parser/parse_clause.c | 17 +++++++++++++++--
src/test/regress/expected/aggregates.out | 21 +++++++++++++++++++++
src/test/regress/sql/aggregates.sql | 6 ++++++
3 files changed, 42 insertions(+), 2 deletions(-)
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index 182181f3a60..2c66a4ead5f 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.198 2010/02/26 02:00:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.199 2010/07/18 19:37:48 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -21,6 +21,7 @@
#include "commands/defrem.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
+#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
#include "parser/analyze.h"
@@ -1430,8 +1431,20 @@ findTargetlistEntrySQL99(ParseState *pstate, Node *node, List **tlist)
foreach(tl, *tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tl);
+ Node *texpr;
- if (equal(expr, tle->expr))
+ /*
+ * Ignore any implicit cast on the existing tlist expression.
+ *
+ * This essentially allows the ORDER/GROUP/etc item to adopt the same
+ * datatype previously selected for a textually-equivalent tlist item.
+ * There can't be any implicit cast at top level in an ordinary SELECT
+ * tlist at this stage, but the case does arise with ORDER BY in an
+ * aggregate function.
+ */
+ texpr = strip_implicit_coercions((Node *) tle->expr);
+
+ if (equal(expr, texpr))
return tle;
}
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index 2460d9dfd62..087b4679d4d 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -830,3 +830,24 @@ select string_agg(a,',') from (values(null),(null)) g(a);
(1 row)
+-- check some implicit casting cases, as per bug #5564
+select string_agg(distinct f1 order by f1) from varchar_tbl; -- ok
+ string_agg
+------------
+ aababcd
+(1 row)
+
+select string_agg(distinct f1::text order by f1) from varchar_tbl; -- not ok
+ERROR: in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list
+LINE 1: select string_agg(distinct f1::text order by f1) from varcha...
+ ^
+select string_agg(distinct f1 order by f1::text) from varchar_tbl; -- not ok
+ERROR: in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list
+LINE 1: select string_agg(distinct f1 order by f1::text) from varcha...
+ ^
+select string_agg(distinct f1::text order by f1::text) from varchar_tbl; -- ok
+ string_agg
+------------
+ aababcd
+(1 row)
+
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index daa89167a20..b2199d1ce94 100644
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -362,3 +362,9 @@ select string_agg(a,',') from (values('aaaa'),('bbbb'),('cccc')) g(a);
select string_agg(a,',') from (values('aaaa'),(null),('bbbb'),('cccc')) g(a);
select string_agg(a,',') from (values(null),(null),('bbbb'),('cccc')) g(a);
select string_agg(a,',') from (values(null),(null)) g(a);
+
+-- check some implicit casting cases, as per bug #5564
+select string_agg(distinct f1 order by f1) from varchar_tbl; -- ok
+select string_agg(distinct f1::text order by f1) from varchar_tbl; -- not ok
+select string_agg(distinct f1 order by f1::text) from varchar_tbl; -- not ok
+select string_agg(distinct f1::text order by f1::text) from varchar_tbl; -- ok
--
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