From: cluster <skrald@amossen.dk>
To: pgsql-performance@postgresql.org
Subject: Appending "LIMIT" to query drastically decreases performance
Date: Fri, 30 Nov 2007 12:16:08 +0100
Message-ID: <fiordm$2aev$1@news.hub.org> (raw)
Can anyone explain the following odd behavior?
I have a query that completes in about 90 ms. If I append LIMIT to the
very end, eg. "LIMIT 500" the evaluation time increases to about 800 ms.
How can performance get *worse* by giving the database the option to
stop the evaluation earlier (when it reaches the output 500 rows)?
I have pasted both queries together with output from explain analyze here:
http://pastebin.com/m3c0d1896
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To: pgsql-performance@postgresql.org
Cc: skrald@amossen.dk
Subject: Re: Appending "LIMIT" to query drastically decreases performance
In-Reply-To: <fiordm$2aev$1@news.hub.org>
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