From: | Daniel Kalchev <daniel(at)digsys(dot)bg> |
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To: | Manfred Koizar <mkoi-pg(at)aon(dot)at> |
Cc: | "PostgresSQL Hackers Mailing List" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Offering tuned config files |
Date: | 2003-02-14 12:24:23 |
Message-ID: | 200302141224.h1ECONY08877@dcave.digsys.bg |
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Lists: | pgsql-hackers |
>>>Manfred Koizar said:
> effective_cache_size = 20000 (~ 160 MB) should be more adequate for a
> 256 MB machine than the extremely conservative default of 1000. I
> admit that the effect of this change is hard to benchmark. A way too
> low (or too high) setting may lead the planner to wrong conclusions.
The default on BSD systems is 10% of the total RAM, so on a 256MB machine this
would be ~26MB or effective_cache_size = 32000.
One could always modify the kernel to support much larger value, but I doubt
this is done in many cases and the usefulness of larger buffer cache is not
obvious in the presence of many fsync calls (which might be typicall). I could
be wrong, of course :)
In any case, the default is indeed low and would prevent using indexes on
larger tables, where they are most useful.
Daniel
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