Back in the 8.3 cycle (2007) when the autovacuum launcher/worker split was done, we annoyed people because it blocked DDL. That led to an effort to cancel autovac automatically when that was detected, by Simon Riggs. https://postgr.es/m/1191526327.4223.204.ca...@ebony.site https://postgr.es/m/1192129897.4233.433.ca...@ebony.site
I was fixated on only cancelling when it was ANALYZE, to avoid losing any VACUUM work. https://postgr.es/m/20071025164150.gf23...@alvh.no-ip.org That turned into some flags for PGPROC to detect whether a process was ANALYZE, and cancel only those. https://postgr.es/m/20071024151328.gg6...@alvh.no-ip.org Commit: https://postgr.es/m/20071024205536.cb425754...@cvs.postgresql.org https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=745c1b2c2ab However, I was outvoted, so we do not limit cancellation to analyze. Patch and discussion: https://postgr.es/m/20071025164150.gf23...@alvh.no-ip.org Commit: https://postgr.es/m/20071026204510.aa02e754...@cvs.postgresql.org https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=acac68b2bca ... which means the flag I had added two days earlier has never been used for anything. We've carried the flag forward to this day for almost 13 years, dutifully turning it on and off ... but never checking it anywhere. I propose to remove it, as in the attached patch. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>From f96b28defe856e284a44b207c2016c72a48a2ff2 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera <alvhe...@alvh.no-ip.org> Date: Wed, 5 Aug 2020 18:57:50 -0400 Subject: [PATCH] Remove PROC_IN_ANALYZE --- src/backend/commands/analyze.c | 13 +------------ src/include/storage/proc.h | 3 +-- src/include/storage/procarray.h | 7 ------- 3 files changed, 2 insertions(+), 21 deletions(-) diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c index 924ef37c81..e0fa73ba79 100644 --- a/src/backend/commands/analyze.c +++ b/src/backend/commands/analyze.c @@ -247,11 +247,8 @@ analyze_rel(Oid relid, RangeVar *relation, } /* - * OK, let's do it. First let other backends know I'm in ANALYZE. + * OK, let's do it. First, initialize progress reporting. */ - LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); - MyPgXact->vacuumFlags |= PROC_IN_ANALYZE; - LWLockRelease(ProcArrayLock); pgstat_progress_start_command(PROGRESS_COMMAND_ANALYZE, RelationGetRelid(onerel)); @@ -279,14 +276,6 @@ analyze_rel(Oid relid, RangeVar *relation, relation_close(onerel, NoLock); pgstat_progress_end_command(); - - /* - * Reset my PGXACT flag. Note: we need this here, and not in vacuum_rel, - * because the vacuum flag is cleared by the end-of-xact code. - */ - LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); - MyPgXact->vacuumFlags &= ~PROC_IN_ANALYZE; - LWLockRelease(ProcArrayLock); } /* diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h index b20e2ad4f6..5ceb2494ba 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -52,7 +52,6 @@ struct XidCache */ #define PROC_IS_AUTOVACUUM 0x01 /* is it an autovac worker? */ #define PROC_IN_VACUUM 0x02 /* currently running lazy vacuum */ -#define PROC_IN_ANALYZE 0x04 /* currently running analyze */ #define PROC_VACUUM_FOR_WRAPAROUND 0x08 /* set by autovac only */ #define PROC_IN_LOGICAL_DECODING 0x10 /* currently doing logical * decoding outside xact */ @@ -60,7 +59,7 @@ struct XidCache /* flags reset at EOXact */ #define PROC_VACUUM_STATE_MASK \ - (PROC_IN_VACUUM | PROC_IN_ANALYZE | PROC_VACUUM_FOR_WRAPAROUND) + (PROC_IN_VACUUM | PROC_VACUUM_FOR_WRAPAROUND) /* * We allow a small number of "weak" relation locks (AccessShareLock, diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h index a5c7d0c064..01040d76e1 100644 --- a/src/include/storage/procarray.h +++ b/src/include/storage/procarray.h @@ -29,8 +29,6 @@ */ #define PROCARRAY_VACUUM_FLAG 0x02 /* currently running lazy * vacuum */ -#define PROCARRAY_ANALYZE_FLAG 0x04 /* currently running - * analyze */ #define PROCARRAY_LOGICAL_DECODING_FLAG 0x10 /* currently doing logical * decoding outside xact */ @@ -42,7 +40,6 @@ * have no corresponding PROC flag equivalent. */ #define PROCARRAY_PROC_FLAGS_MASK (PROCARRAY_VACUUM_FLAG | \ - PROCARRAY_ANALYZE_FLAG | \ PROCARRAY_LOGICAL_DECODING_FLAG) /* Use the following flags as an input "flags" to GetOldestXmin function */ @@ -50,10 +47,6 @@ #define PROCARRAY_FLAGS_DEFAULT PROCARRAY_LOGICAL_DECODING_FLAG /* Ignore vacuum backends */ #define PROCARRAY_FLAGS_VACUUM PROCARRAY_FLAGS_DEFAULT | PROCARRAY_VACUUM_FLAG -/* Ignore analyze backends */ -#define PROCARRAY_FLAGS_ANALYZE PROCARRAY_FLAGS_DEFAULT | PROCARRAY_ANALYZE_FLAG -/* Ignore both vacuum and analyze backends */ -#define PROCARRAY_FLAGS_VACUUM_ANALYZE PROCARRAY_FLAGS_DEFAULT | PROCARRAY_VACUUM_FLAG | PROCARRAY_ANALYZE_FLAG extern Size ProcArrayShmemSize(void); extern void CreateSharedProcArray(void); -- 2.20.1
