From 7b6a37f5ec2e99e70715a34916eac78bad928def Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 21 Feb 2012 15:03:56 -0500 Subject: [PATCH] Don't clear btpo_cycleid during _bt_vacuum_one_page. When "vacuuming" a single btree page by removing LP_DEAD tuples, we are not actually within a vacuum operation, but rather in an ordinary insertion process that could well be running concurrently with a vacuum. So clearing the cycleid is incorrect, and could cause the concurrent vacuum to miss removing tuples that it needs to remove. This is a longstanding bug introduced by commit e6284649b9e30372b3990107a082bc7520325676 of 2006-07-25. I believe it explains Maxim Boguk's recent report of index corruption, and probably some other previously unexplained reports. In 9.0 and up this is a one-line fix; before that we need to introduce a flag to tell _bt_delitems what to do. --- src/backend/access/nbtree/nbtinsert.c | 2 +- src/backend/access/nbtree/nbtpage.c | 10 ++++++---- src/backend/access/nbtree/nbtree.c | 2 +- src/include/access/nbtree.h | 2 +- 4 files changed, 9 insertions(+), 7 deletions(-) diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c index da82265705..f866143e59 100644 --- a/src/backend/access/nbtree/nbtinsert.c +++ b/src/backend/access/nbtree/nbtinsert.c @@ -1978,7 +1978,7 @@ _bt_vacuum_one_page(Relation rel, Buffer buffer) } if (ndeletable > 0) - _bt_delitems(rel, buffer, deletable, ndeletable); + _bt_delitems(rel, buffer, deletable, ndeletable, false); /* * Note: if we didn't find any LP_DEAD items, then the page's diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c index 0688c2c7d8..ad458a9fe4 100644 --- a/src/backend/access/nbtree/nbtpage.c +++ b/src/backend/access/nbtree/nbtpage.c @@ -656,7 +656,8 @@ _bt_page_recyclable(Page page) */ void _bt_delitems(Relation rel, Buffer buf, - OffsetNumber *itemnos, int nitems) + OffsetNumber *itemnos, int nitems, + bool inVacuum) { Page page = BufferGetPage(buf); BTPageOpaque opaque; @@ -668,11 +669,12 @@ _bt_delitems(Relation rel, Buffer buf, PageIndexMultiDelete(page, itemnos, nitems); /* - * We can clear the vacuum cycle ID since this page has certainly been - * processed by the current vacuum scan. + * If this is within VACUUM, we can clear the vacuum cycle ID since this + * page has certainly been processed by the current vacuum scan. */ opaque = (BTPageOpaque) PageGetSpecialPointer(page); - opaque->btpo_cycleid = 0; + if (inVacuum) + opaque->btpo_cycleid = 0; /* * Mark the page as not containing any LP_DEAD items. This is not diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c index 2b76e7cd45..1ffc91f0de 100644 --- a/src/backend/access/nbtree/nbtree.c +++ b/src/backend/access/nbtree/nbtree.c @@ -857,7 +857,7 @@ restart: */ if (ndeletable > 0) { - _bt_delitems(rel, buf, deletable, ndeletable); + _bt_delitems(rel, buf, deletable, ndeletable, true); stats->tuples_removed += ndeletable; /* must recompute maxoff */ maxoff = PageGetMaxOffsetNumber(page); diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h index 1d3e42d99b..7656c488e1 100644 --- a/src/include/access/nbtree.h +++ b/src/include/access/nbtree.h @@ -537,7 +537,7 @@ extern void _bt_relbuf(Relation rel, Buffer buf); extern void _bt_pageinit(Page page, Size size); extern bool _bt_page_recyclable(Page page); extern void _bt_delitems(Relation rel, Buffer buf, - OffsetNumber *itemnos, int nitems); + OffsetNumber *itemnos, int nitems, bool inVacuum); extern int _bt_pagedel(Relation rel, Buffer buf, BTStack stack, bool vacuum_full);