| From: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz> | 
|---|---|
| To: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> | 
| Cc: | Adonias Malosso <malosso(at)gmail(dot)com>, Claus Guttesen <kometen(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org | 
| Subject: | Re: 4s query want to run faster | 
| Date: | 2008-02-22 05:10:18 | 
| Message-ID: | 47BE593A.8000709@paradise.net.nz | 
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| Lists: | pgsql-performance | 
Scott Marlowe wrote:
>
> effective_cache_size is pretty easy to set, and it's not real
> sensitive to small changes, so guesstimation is fine where it's
> concerned.  Basically, let your machine run for a while, then  add the
> cache and buffer your unix kernel has altogether (top and free will
> tell you these things).  If you're running other apps on the server,
> make a SWAG (scientific wild assed guess) how much the other apps are
> pounding on the kernel cache / buffer and set effective_cache_size to
> how much you think postgresql is using of the total and set it to
> that.
>   
FWIW - The buffered|cached may well be called something different if you 
are not on Linux (I didn't see any platform mentioned - sorry if I 
missed it) - e.g for Freebsd it is "Inactive" that shows what the os is 
caching and "Cached" actually means something slightly different... (yep 
that's caused a lot of confusion in the past...)
Cheers
Mark
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