From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Bill Moran <wmoran(at)collaborativefusion(dot)com> |
Cc: | David Brain <dbrain(at)bandwidth(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Potential memory usage issue |
Date: | 2007-03-22 15:35:36 |
Message-ID: | 3701.1174577736@sss.pgh.pa.us |
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Lists: | pgsql-performance |
Bill Moran <wmoran(at)collaborativefusion(dot)com> writes:
> In response to David Brain <dbrain(at)bandwidth(dot)com>:
>> I am curious as to why 'top' gives such different output on the two
>> systems - the datasets are large and so I know I benefit from having
>> high shared_buffers and effective_cache_size settings.
> Have you done any actual queries on the new system? PG won't use the
> shm until it needs it -- and that doesn't occur until it gets a request
> for data via a query.
More accurately, top won't consider shared mem to be part of the process
address space until it's actually touched by that process.
regards, tom lane
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