From 8fa4a1ac61189efffb8b851ee77e1bc87360c445 Mon Sep 17 00:00:00 2001 From: Noah Misch Date: Thu, 1 Feb 2024 13:44:19 -0800 Subject: [PATCH] Sync PG_VERSION file in CREATE DATABASE. An OS crash could leave PG_VERSION empty or missing. The same symptom appeared in a backup by block device snapshot, taken after the next checkpoint and before the OS flushes the PG_VERSION blocks. Device snapshots are not a documented backup method, however. Back-patch to v15, where commit 9c08aea6a3090a396be334cc58c511edab05776a introduced STRATEGY=WAL_LOG and made it the default. Discussion: https://postgr.es/m/20240130195003.0a.nmisch@google.com --- doc/src/sgml/monitoring.sgml | 5 +++++ src/backend/commands/dbcommands.c | 8 ++++++++ src/backend/utils/activity/wait_event.c | 3 +++ src/include/utils/wait_event.h | 3 ++- 4 files changed, 18 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index c72ad60fa0..84e65002ff 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -1519,6 +1519,11 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser TwophaseFileWrite Waiting for a write of a two phase state file. + + VersionFileSync + Waiting for the version file to reach durable storage while + creating a database. + VersionFileWrite Waiting for the version file to be written while creating a database. diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c index 79c5988963..5ced6da20b 100644 --- a/src/backend/commands/dbcommands.c +++ b/src/backend/commands/dbcommands.c @@ -507,6 +507,14 @@ CreateDirAndVersionFile(char *dbpath, Oid dbid, Oid tsid, bool isRedo) } pgstat_report_wait_end(); + pgstat_report_wait_start(WAIT_EVENT_VERSION_FILE_SYNC); + if (pg_fsync(fd) != 0) + ereport(data_sync_elevel(ERROR), + (errcode_for_file_access(), + errmsg("could not fsync file \"%s\": %m", versionfile))); + fsync_fname(dbpath, true); + pgstat_report_wait_end(); + /* Close the version file. */ CloseTransientFile(fd); diff --git a/src/backend/utils/activity/wait_event.c b/src/backend/utils/activity/wait_event.c index 87c15b9c6f..787525754a 100644 --- a/src/backend/utils/activity/wait_event.c +++ b/src/backend/utils/activity/wait_event.c @@ -702,6 +702,9 @@ pgstat_get_wait_io(WaitEventIO w) case WAIT_EVENT_TWOPHASE_FILE_WRITE: event_name = "TwophaseFileWrite"; break; + case WAIT_EVENT_VERSION_FILE_SYNC: + event_name = "VersionFileSync"; + break; case WAIT_EVENT_VERSION_FILE_WRITE: event_name = "VersionFileWrite"; break; diff --git a/src/include/utils/wait_event.h b/src/include/utils/wait_event.h index b578e2ec75..c814918d6c 100644 --- a/src/include/utils/wait_event.h +++ b/src/include/utils/wait_event.h @@ -229,7 +229,8 @@ typedef enum WAIT_EVENT_WAL_READ, WAIT_EVENT_WAL_SYNC, WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN, - WAIT_EVENT_WAL_WRITE + WAIT_EVENT_WAL_WRITE, + WAIT_EVENT_VERSION_FILE_SYNC } WaitEventIO;