mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Reduce the acceptable staleness of pgstat data for autovacuum, per the

Browse Source 
longstanding note in the source that this patch removes.
This commit is contained in:
Alvaro Herrera 2008-11-03 19:03:41 +00:00
parent b8fab2411d
commit 88dd4b0a0d
2 changed files with 16 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/postmaster/autovacuum.c
View File

@ -55,7 +55,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.85 2008/11/02 21:24:52 tgl Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.86 2008/11/03 19:03:41 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@ -2149,8 +2149,10 @@ do_autovacuum(void)
* It could have changed if something else processed the table while
* we weren't looking.
*
* FIXME we ignore the possibility that the table was finished being
* vacuumed in the last 500ms (PGSTAT_STAT_INTERVAL). This is a bug.
* Note: we have a special case in pgstat code to ensure that the stats
* we read are as up-to-date as possible, to avoid the problem that
* somebody just finished vacuuming this table. The window to the race
* condition is not closed but it is very small.
*/
MemoryContextSwitchTo(AutovacMemCxt);
tab = table_recheck_autovac(relid, table_toast_map);

15
src/backend/postmaster/pgstat.c
View File

@ -13,7 +13,7 @@
*
* Copyright (c) 2001-2008, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.182 2008/11/03 01:17:08 tgl Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.183 2008/11/03 19:03:41 alvherre Exp $
* ----------
*/
#include "postgres.h"
@ -3381,7 +3381,10 @@ backend_read_statsfile(void)
/*
* We set the minimum acceptable timestamp to PGSTAT_STAT_INTERVAL msec
* before now. This indirectly ensures that the collector needn't write
* the file more often than PGSTAT_STAT_INTERVAL.
* the file more often than PGSTAT_STAT_INTERVAL. In an autovacuum
* worker, however, we want a lower delay to avoid using stale data, so we
* use PGSTAT_RETRY_DELAY (since the number of worker is low, this
* shouldn't be a problem).
*
* Note that we don't recompute min_ts after sleeping; so we might end up
* accepting a file a bit older than PGSTAT_STAT_INTERVAL. In practice
@ -3389,8 +3392,12 @@ backend_read_statsfile(void)
* PGSTAT_STAT_INTERVAL; and we don't want to lie to the collector about
* what our cutoff time really is.
*/
min_ts = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
-PGSTAT_STAT_INTERVAL);
if (IsAutoVacuumWorkerProcess())
min_ts = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
-PGSTAT_RETRY_DELAY);
else
min_ts = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
-PGSTAT_STAT_INTERVAL);
/*
* Loop until fresh enough stats file is available or we ran out of time.