From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Michael van Rooyen <michael(at)loot(dot)co(dot)za> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Slow queries on 9.3.1 despite use of index |
Date: | 2014-04-28 17:50:20 |
Message-ID: | 23166.1398707420@sss.pgh.pa.us |
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Lists: | pgsql-performance |
Michael van Rooyen <michael(at)loot(dot)co(dot)za> writes:
> I'm trying to get to the bottom of a performance issue on a server
> running PostgreSQL 9.3.1 on Centos 5.
Hm ... it seems pretty suspicious that all of these examples take just
about exactly 1 second longer than you might expect. I'm wondering
if there is something sitting on an exclusive table lock somewhere,
and releasing it after 1 second.
In particular, this looks quite a bit like the old behavior of autovacuum
when it was trying to truncate empty pages off the end of a relation ---
it would hold off other accesses to the table until deadlock_timeout
elapsed, whereupon it'd get kicked off the exclusive lock (and have to
retry the truncation next time). Are you *sure* this server is running
9.3.1, and not something pre-9.3?
regards, tom lane
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