Re: Script to compute random page cost
От | Bruce Momjian |
---|---|
Тема | Re: Script to compute random page cost |
Дата | |
Msg-id | 200209101528.g8AFSOW14990@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: Script to compute random page cost (Oliver Elphick <olly@lfix.co.uk>) |
Список | pgsql-hackers |
Oliver Elphick wrote: > Available memory (512M) exceeds the total database size, so sequential > and random are almost the same for the second and subsequent runs. > > Since, in production, I would hope to have all active tables permanently > in RAM, would there be a case for my using a page cost of 1 on the > assumption that no disk reads would be needed? Yes, in your case random_page_cost would be 1 once the data gets into RAM. In fact, that is the reason I used only /data/base for testing so places where data can load into ram will see lower random pages costs. I could just create a random file and test on that but it isn't the same. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania19073
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