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Re: Large database help

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: xbdelacour(at)yahoo(dot)com
Cc: Ragnar Kjørstad <postgres(at)ragnark(dot)vestdata(dot)no>, pgsql-admin(at)postgresql(dot)org
Subject: Re: Large database help
Date: 2001-04-24 00:24:16
Message-ID: 24501.988071856@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-admin
xbdelacour(at)yahoo(dot)com writes:
> I'm no Unix expert, but this would seem to indicate that shmget is 
> successfully allocating 400385024/1024/1024=381MB of shared memory. I don't 
> know enough about how the postgres parent/child/shmem scheme works to know 
> why this is working yet the children only register 12MB of shared memory 
> under top.

On most of the systems I've worked on, top does not seem to count shmem
blocks that a process is attached to in the process' memory usage.  So
that doesn't prove much one way or the other.

I am wondering if your version of 'top' fails to count swapped-out shmem
segments against swap space, or something like that.  That'd be a tad
weird, but it seems very improbable that your machine is not swapping;
I just do not believe top's claim that no swapping is happening.

Anyway, the most direct experiment would be to reduce your -B request to
100MB or so and see how things change...

			regards, tom lane

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