Re: Nested Loop "Killer" on 8.1

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Dave North" <DNorth(at)signiant(dot)com>
Cc: "Greg Stark" <gsstark(at)mit(dot)edu>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Nested Loop "Killer" on 8.1
Date: 2009-06-26 22:22:00
Message-ID: 10310.1246054920@sss.pgh.pa.us
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"Dave North" <DNorth(at)signiant(dot)com> writes:
> The outstanding question here is why does the explain analyze take
> (quite a bit) longer than just executing the query?

EXPLAIN ANALYZE has nontrivial measurement overhead, especially on
platforms with slow gettimeofday(). Old/cheap PC hardware, in particular,
tends to suck in this respect.

regards, tom lane

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