From 9bb648c44bc6afa3e7e55cd2482f979209622ab4 Mon Sep 17 00:00:00 2001 From: "dgrowley@gmail.com" Date: Tue, 26 Feb 2019 02:10:50 +1300 Subject: [PATCH v1] 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. --- doc/src/sgml/config.sgml | 2 +- src/backend/utils/init/globals.c | 2 +- src/backend/utils/misc/guc.c | 2 +- src/backend/utils/misc/postgresql.conf.sample | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 8bd57f376b..d03b2bd0ce 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 fd51934aaf..a6ce184537 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 156d147c85..826c189a96 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 194f312096..5e34b53773 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 - -- 2.17.1