From 69c7f25bed1a3dc1a8343b60411d8d9884cfc956 Mon Sep 17 00:00:00 2001 From: "Marc G. Fournier" Date: Wed, 30 Oct 1996 06:08:10 +0000 Subject: [PATCH] Fixes: I found another bug in btree index. Looking at the code it seems that NULL keys are never used to build or scan a btree index (see the explain commands in the example). However this is not the case when a null key is retrieved in an outer loop of a join select and used in an index scan of an inner loop. This bug causes at least three kinds of problems: 1) the backend crashes when it tries to compare a text string with a null. 2) it is not possible to find tuples with null keys in a join. 3) null is considered equal to 0 when the datum is passed by value, see the last query. Submitted by: Massimo Dal Zotto --- src/backend/access/common/heapvalid.c | 6 +++++- src/backend/access/common/indexvalid.c | 6 +++++- src/backend/access/nbtree/nbtsearch.c | 29 ++++++++++++++++++++++++-- src/backend/executor/nodeIndexscan.c | 7 ++++++- 4 files changed, 43 insertions(+), 5 deletions(-) diff --git a/src/backend/access/common/heapvalid.c b/src/backend/access/common/heapvalid.c index 45003095b2..c50700c203 100644 --- a/src/backend/access/common/heapvalid.c +++ b/src/backend/access/common/heapvalid.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.6 1996/10/21 11:49:36 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.7 1996/10/30 06:07:56 scrappy Exp $ * *------------------------------------------------------------------------- */ @@ -71,6 +71,10 @@ heap_keytest(HeapTuple t, /* XXX eventually should check if SK_ISNULL */ return false; + if (keys->sk_flags & SK_ISNULL) { + return (false); + } + if (keys->sk_flags & SK_COMMUTE) test = (long) FMGR_PTR2(keys->sk_func, keys->sk_procedure, keys->sk_argument, atp); diff --git a/src/backend/access/common/indexvalid.c b/src/backend/access/common/indexvalid.c index b5854db569..23b3437460 100644 --- a/src/backend/access/common/indexvalid.c +++ b/src/backend/access/common/indexvalid.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/common/Attic/indexvalid.c,v 1.6 1996/10/21 11:49:38 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/common/Attic/indexvalid.c,v 1.7 1996/10/30 06:07:55 scrappy Exp $ * *------------------------------------------------------------------------- */ @@ -68,6 +68,10 @@ index_keytest(IndexTuple tuple, return (false); } + if (key[0].sk_flags & SK_ISNULL) { + return (false); + } + if (key[0].sk_flags & SK_COMMUTE) { test = (int) (*(key[0].sk_func)) (DatumGetPointer(key[0].sk_argument), diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c index 4551afbf05..3d3ff08524 100644 --- a/src/backend/access/nbtree/nbtsearch.c +++ b/src/backend/access/nbtree/nbtsearch.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.4 1996/10/23 07:39:10 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.5 1996/10/30 06:08:01 scrappy Exp $ * *------------------------------------------------------------------------- */ @@ -269,6 +269,18 @@ _bt_skeycmp(Relation rel, &isNull); keyDatum = entry->sk_argument; + /* + * This may happen in a nested loop if an attribute used + * as scan key is null. DZ 29-10-1996 + */ + if ((entry->sk_flags & SK_ISNULL) || (isNull)) { + if ((entry->sk_flags & SK_ISNULL) && (isNull)) { + return (true); + } else { + return (false); + } + } + compare = _bt_invokestrat(rel, i, strat, keyDatum, attrDatum); if (!compare) return (false); @@ -501,6 +513,19 @@ _bt_compare(Relation rel, entry = &scankey[i - 1]; attno = entry->sk_attno; datum = index_getattr(itup, attno, itupdesc, &null); + + /* + * This may happen in a nested loop if an attribute used + * as scan key is null. DZ 29-10-1996 + */ + if ((entry->sk_flags & SK_ISNULL) || (null)) { + if ((entry->sk_flags & SK_ISNULL) && (null)) { + return (0); + } else { + return (null ? +1 : -1); + } + } + tmpres = (long) FMGR_PTR2(entry->sk_func, entry->sk_procedure, entry->sk_argument, datum); result = tmpres; @@ -641,7 +666,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) * hardwired attno == 1. */ proc = index_getprocid(rel, 1, BTORDER_PROC); - ScanKeyEntryInitialize(&skdata, 0x0, 1, proc, + ScanKeyEntryInitialize(&skdata, so->keyData[0].sk_flags, 1, proc, so->keyData[0].sk_argument); stack = _bt_search(rel, 1, &skdata, &buf); diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c index 758fabdefe..b8acb7897b 100644 --- a/src/backend/executor/nodeIndexscan.c +++ b/src/backend/executor/nodeIndexscan.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.1.1.1 1996/07/09 06:21:26 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.2 1996/10/30 06:08:10 scrappy Exp $ * *------------------------------------------------------------------------- */ @@ -273,6 +273,11 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan* parent) scanvalue = (Datum) ExecEvalExpr(scanexpr, exprCtxt, &isNull, &isDone); scan_keys[j].sk_argument = scanvalue; + if (isNull) { + scan_keys[j].sk_flags |= SK_ISNULL; + } else { + scan_keys[j].sk_flags &= ~SK_ISNULL; + } } } }