upping checkpoints on production server
От | Robert Treat |
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Тема | upping checkpoints on production server |
Дата | |
Msg-id | 1064438654.25702.2076.camel@camel обсуждение исходный текст |
Ответы |
Re: upping checkpoints on production server
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Список | pgsql-performance |
All this talk of checkpoints got me wondering if I have them set at an optimum level on my production servers. I noticed the following in the docs: "There will be at least one 16 MB segment file, and will normally not be more than 2 * checkpoint_segments + 1 files. You can use this to estimate space requirements for WAL. Ordinarily, when old log segment files are no longer needed, they are recycled (renamed to become the next segments in the numbered sequence). If, due to a short-term peak of log output rate, there are more than 2 * checkpoint_segments + 1 segment files, the unneeded segment files will be deleted instead of recycled until the system gets back under this limit." In .conf file I have default checkpoints set to 3, but I noticed that in my pg_xlog directory I always seem to have at least 8 log files. Since this is more than the suggested 7, I'm wondering if this means I ought to bump my checkpoint segments up to 4? I don't really want to bump it up unnecessarily as quick recover time is important on this box, however if i would get an overall performance boost it seems like it would be worth it, and given that I seem to be using more than the default number anyways... I've always treated wal logs as self maintaining, am I over analyzing this? Another thought popped into my head, is it just coincidence that I always seem to have 8 files and that wal_buffers defaults to 8? Seems like it's not but I love a good conspiracy theory. Robert Treat -- Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL
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