From 51c24d9e21d7c36cbb6890655fd8f57270cdb15a Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Wed, 26 Oct 2022 09:41:26 +0900 Subject: [PATCH] Fix ordering issue with WAL operations in GIN fast insert path MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Contrary to what is documented in src/backend/access/transam/README, ginHeapTupleFastInsert() had a few ordering issues with the way it does its WAL operations when inserting items in its fast path. First, when using a separate list, XLogBeginInsert() was being always called before START_CRIT_SECTION(), and in this case a second thing was wrong when merging lists, as an exclusive lock was taken on the tail page *before* calling XLogBeginInsert(). Finally, when inserting items into a tail page, the order of XLogBeginInsert() and START_CRIT_SECTION() was reversed. This commit addresses all these issues by moving the calls of XLogBeginInsert() after all the pages logged are locked and pinned, within a critical section. This has been applied first only on HEAD as of 56b6625, but as per discussion with Tom Lane and Álvaro Herrera, a backpatch is preferred to keep all the branches consistent and to respect the transam's README where we can. Author: Matthias van de Meent, Zhang Mingli Discussion: https://postgr.es/m/CAEze2WhL8uLMqynnnCu1LAPwxD5RKEo0nHV+eXGg_N6ELU88HQ@mail.gmail.com Backpatch-through: 10 --- src/backend/access/gin/ginfast.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c index 2b3dd1c677..a7a49b36fd 100644 --- a/src/backend/access/gin/ginfast.c +++ b/src/backend/access/gin/ginfast.c @@ -284,9 +284,6 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) memset(&sublist, 0, sizeof(GinMetaPageData)); makeSublist(index, collector->tuples, collector->ntuples, &sublist); - if (needWal) - XLogBeginInsert(); - /* * metapage was unlocked, see above */ @@ -306,6 +303,9 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) metadata->nPendingPages = sublist.nPendingPages; metadata->nPendingHeapTuples = sublist.nPendingHeapTuples; + + if (needWal) + XLogBeginInsert(); } else { @@ -334,7 +334,10 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) metadata->nPendingHeapTuples += sublist.nPendingHeapTuples; if (needWal) + { + XLogBeginInsert(); XLogRegisterBuffer(1, buffer, REGBUF_STANDARD); + } } } else @@ -360,11 +363,11 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) data.ntuples = collector->ntuples; + START_CRIT_SECTION(); + if (needWal) XLogBeginInsert(); - START_CRIT_SECTION(); - /* * Increase counter of heap tuples */