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Fix bug in detecting concurrent page splits in GiST insert

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In commit 9eb5607e699, I got the condition on checking for split or
deleted page wrong: I used && instead of ||. The comment correctly said
"concurrent split _or_ deletion".

As a result, GiST insertion could miss a concurrent split, and insert to
wrong page. Duncan Sands demonstrated this with a test script that did a
lot of concurrent inserts.

Backpatch to v12, where this was introduced. REINDEX is required to fix
indexes that were affected by this bug.

Backpatch-through: 12
Reported-by: Duncan Sands
Discussion: https://www.postgresql.org/message-id/a9690483-6c6c-3c82-c8ba-dc1a40848f11%40deepbluecap.com
This commit is contained in:
Heikki Linnakangas 2021-01-20 11:58:03 +02:00
parent 31e0f9d76b
commit b8403d140f
1 changed files with 4 additions and 1 deletions
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5
src/backend/access/gist/gist.c
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@ -246,6 +246,9 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
if (GistFollowRight(page)) if (GistFollowRight(page))
elog(ERROR, "concurrent GiST page split was incomplete"); elog(ERROR, "concurrent GiST page split was incomplete");
/* should never try to insert to a deleted page */
Assert(!GistPageIsDeleted(page));
*splitinfo = NIL; *splitinfo = NIL;
/* /*
@ -861,7 +864,7 @@ gistdoinsert(Relation r, IndexTuple itup, Size freespace,
*/ */
} }
else if ((GistFollowRight(stack->page) || else if ((GistFollowRight(stack->page) ||
stack->parent->lsn < GistPageGetNSN(stack->page)) && stack->parent->lsn < GistPageGetNSN(stack->page)) ||
GistPageIsDeleted(stack->page)) GistPageIsDeleted(stack->page))
{ {
/* /*