From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bill Moran <wmoran@collaborativefusion.com>
Cc: David Brain <dbrain@bandwidth.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Potential memory usage issue
Date: Thu, 22 Mar 2007 11:35:36 -0400
Message-ID: <3701.1174577736@sss.pgh.pa.us> (raw)
In-Reply-To: <20070322091700.9d1553e6.wmoran@collaborativefusion.com>
References: <460271B9.8050600@bandwidth.com>
<20070322085037.54780906.wmoran@collaborativefusion.com>
<46027F65.9080909@bandwidth.com>
<20070322091700.9d1553e6.wmoran@collaborativefusion.com>
Bill Moran <wmoran@collaborativefusion.com> writes:
> In response to David Brain <dbrain@bandwidth.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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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, wmoran@collaborativefusion.com, dbrain@bandwidth.com
Subject: Re: Potential memory usage issue
In-Reply-To: <3701.1174577736@sss.pgh.pa.us>
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