From 19cd31b0682d32142edf7599b653d4eff7031a8c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 17 Aug 2004 23:15:33 +0000 Subject: [PATCH] Fix bug introduced into _bt_getstackbuf() on 2003-Feb-21: the initial value of 'start' could be past the end of the page, if the page was split by some concurrent inserting process since we visited it. In this situation the code could look at bogus entries and possibly find a match (since after all those entries still contain what they had before the split). This would lead to 'specified item offset is too large' followed by 'PANIC: failed to add item to the page', as reported by Joe Conway for scenarios involving heavy concurrent insertion activity. --- src/backend/access/nbtree/nbtinsert.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c index ed08d65d99..7cc019d874 100644 --- a/src/backend/access/nbtree/nbtinsert.c +++ b/src/backend/access/nbtree/nbtinsert.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.113 2004/07/21 22:31:19 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.114 2004/08/17 23:15:33 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1311,6 +1311,13 @@ _bt_getstackbuf(Relation rel, BTStack stack, int access) if (start < minoff) start = minoff; + /* + * Need this check too, to guard against possibility that page + * split since we visited it originally. + */ + if (start > maxoff) + start = OffsetNumberNext(maxoff); + /* * These loops will check every item on the page --- but in an * order that's attuned to the probability of where it