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Re: Persistent Plan Cache

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Joshua Rubin <jrubin(at)esoft(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Persistent Plan Cache
Date: 2009-09-13 17:45:25
Message-ID: 2971.1252863925@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Joshua Rubin <jrubin(at)esoft(dot)com> writes:
> We have a very large, partitioned, table that we often need to query
> from new connections, but frequently with similar queries. We have
> constraint exclusion on to take advantage of the partitioning. This also
> makes query planning more expensive. As a result, the CPU is fully
> loaded, all the time, preparing queries, many of which have been
> prepared, identically, by other connections.

If you're depending on constraint exclusion, it's hard to see how plan
caching could help you at all.  The generated plan needs to vary
depending on the actual WHERE-clause parameters.

			regards, tom lane

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