Increase the default vacuum_cost_limit from 200 to 2000
The original 200 default value was set back inf425b605f4
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 (9cd00c457e
) 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
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@ -1929,7 +1929,7 @@ include_dir 'conf.d'
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<listitem>
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<para>
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The accumulated cost that will cause the vacuuming process to sleep.
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The default value is 200.
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The default value is 2000.
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</para>
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</listitem>
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</varlistentry>
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@ -137,7 +137,7 @@ int MaxBackends = 0;
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int VacuumCostPageHit = 1; /* GUC parameters for vacuum */
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int VacuumCostPageMiss = 10;
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int VacuumCostPageDirty = 20;
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int VacuumCostLimit = 200;
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int VacuumCostLimit = 2000;
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int VacuumCostDelay = 0;
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int VacuumPageHit = 0;
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@ -2268,7 +2268,7 @@ static struct config_int ConfigureNamesInt[] =
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NULL
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},
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&VacuumCostLimit,
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200, 1, 10000,
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2000, 1, 10000,
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NULL, NULL, NULL
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},
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@ -159,7 +159,7 @@
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#vacuum_cost_page_hit = 1 # 0-10000 credits
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#vacuum_cost_page_miss = 10 # 0-10000 credits
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#vacuum_cost_page_dirty = 20 # 0-10000 credits
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#vacuum_cost_limit = 200 # 1-10000 credits
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#vacuum_cost_limit = 2000 # 1-10000 credits
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# - Background Writer -
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