From cc62dc2032159e2bb7c7008a28f7d0777e0cc22f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 10 Jul 1999 18:21:59 +0000
Subject: [PATCH] Fix tuplecmp() to ensure repeatable sort ordering of tuples
that contain null fields. Old code would produce erratic sort results
because comparisons of tuples containing nulls could produce inconsistent
answers.
---
src/backend/utils/sort/lselect.c | 56 ++++++++++++++++++--------------
1 file changed, 32 insertions(+), 24 deletions(-)
diff --git a/src/backend/utils/sort/lselect.c b/src/backend/utils/sort/lselect.c
index 230b0b0e9cc..ae10049b961 100644
--- a/src/backend/utils/sort/lselect.c
+++ b/src/backend/utils/sort/lselect.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/sort/Attic/lselect.c,v 1.15 1999/02/13 23:20:15 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/sort/Attic/lselect.c,v 1.16 1999/07/10 18:21:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -186,41 +186,49 @@ puttuple(struct leftist ** treep,
int
tuplecmp(HeapTuple ltup, HeapTuple rtup, LeftistContext context)
{
- Datum lattr,
- rattr;
- int nkey = 0;
+ int nkey;
int result = 0;
- bool isnull;
if (ltup == (HeapTuple) NULL)
return 0;
if (rtup == (HeapTuple) NULL)
return 1;
- while (nkey < context->nKeys && !result)
+ for (nkey = 0; nkey < context->nKeys; nkey++)
{
- lattr = heap_getattr(ltup,
- context->scanKeys[nkey].sk_attno,
- context->tupDesc, &isnull);
- if (isnull)
- return 0;
- rattr = heap_getattr(rtup,
- context->scanKeys[nkey].sk_attno,
- context->tupDesc,
- &isnull);
- if (isnull)
+ ScanKey thisKey = & context->scanKeys[nkey];
+ Datum lattr,
+ rattr;
+ bool lisnull,
+ risnull;
+
+ lattr = heap_getattr(ltup, thisKey->sk_attno,
+ context->tupDesc, &lisnull);
+ rattr = heap_getattr(rtup, thisKey->sk_attno,
+ context->tupDesc, &risnull);
+ if (lisnull)
+ {
+ if (risnull)
+ continue; /* treat two nulls as equal */
+ return 0; /* else, a null sorts after all else */
+ }
+ if (risnull)
return 1;
- if (context->scanKeys[nkey].sk_flags & SK_COMMUTE)
+ if (thisKey->sk_flags & SK_COMMUTE)
+ {
+ if (!(result =
+ (long) (*fmgr_faddr(&thisKey->sk_func)) (rattr, lattr)))
+ result =
+ -(long) (*fmgr_faddr(&thisKey->sk_func)) (lattr, rattr);
+ }
+ else
{
if (!(result =
- (long) (*fmgr_faddr(&context->scanKeys[nkey].sk_func)) (rattr, lattr)))
+ (long) (*fmgr_faddr(&thisKey->sk_func)) (lattr, rattr)))
result =
- -(long) (*fmgr_faddr(&context->scanKeys[nkey].sk_func)) (lattr, rattr);
+ -(long) (*fmgr_faddr(&thisKey->sk_func)) (rattr, lattr);
}
- else if (!(result =
- (long) (*fmgr_faddr(&context->scanKeys[nkey].sk_func)) (lattr, rattr)))
- result =
- -(long) (*fmgr_faddr(&context->scanKeys[nkey].sk_func)) (rattr, lattr);
- nkey++;
+ if (result)
+ break;
}
return result == 1;
}
--
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