From: Andrew Dunstan Date: Wed, 6 Mar 2019 14:10:12 +0000 (-0500) Subject: Increase the default vacuum_cost_limit from 200 to 2000 X-Git-Tag: REL_12_BETA1~615 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=bd09503e633b8077822bb4daf91625b71ac16253;p=postgresql.git Increase the default vacuum_cost_limit from 200 to 2000 The original 200 default value was set back in f425b605f4e when the cost delay settings were first added. Hardware has improved quite a bit since then and we've also made improvements such as sorting buffers during checkpoints (9cd00c457e6) which should result in less random writes. This low default value was reportedly causing problems with badly configured servers and in the absence of a native method to remove excessive bloat from tables without incurring an AccessExclusiveLock, this often made cleaning up the damage caused by badly configured auto-vacuums difficult. It seems more likely that someone will notice that auto-vacuum is running too quickly than too slowly, so let's go all out and multiple the default value for the setting by 10. With the default vacuum_cost_page_dirty and autovacuum_vacuum_cost_delay (assuming a page size of 8192 bytes), this allows autovacuum a theoretical maximum dirty write rate of around 39MB/s instead of just 3.9MB/s. Author: David Rowley Discussion: https://postgr.es/m/CAKJS1f_YbXC2qTMPyCbmsPiKvZYwpuQNQMohiRXLj1r=8_rYvw@mail.gmail.com --- diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 6d42b7afe73..7bbe8f590b6 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1929,7 +1929,7 @@ include_dir 'conf.d' The accumulated cost that will cause the vacuuming process to sleep. - The default value is 200. + The default value is 2000. diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c index fd51934aaf1..a6ce1845372 100644 --- a/src/backend/utils/init/globals.c +++ b/src/backend/utils/init/globals.c @@ -137,7 +137,7 @@ int MaxBackends = 0; int VacuumCostPageHit = 1; /* GUC parameters for vacuum */ int VacuumCostPageMiss = 10; int VacuumCostPageDirty = 20; -int VacuumCostLimit = 200; +int VacuumCostLimit = 2000; int VacuumCostDelay = 0; int VacuumPageHit = 0; diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 156d147c85b..826c189a967 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -2268,7 +2268,7 @@ static struct config_int ConfigureNamesInt[] = NULL }, &VacuumCostLimit, - 200, 1, 10000, + 2000, 1, 10000, NULL, NULL, NULL }, diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index bd6ea65d0c8..99f1666eef9 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -159,7 +159,7 @@ #vacuum_cost_page_hit = 1 # 0-10000 credits #vacuum_cost_page_miss = 10 # 0-10000 credits #vacuum_cost_page_dirty = 20 # 0-10000 credits -#vacuum_cost_limit = 200 # 1-10000 credits +#vacuum_cost_limit = 2000 # 1-10000 credits # - Background Writer -