From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
---|---|
To: | dan(at)sidhe(dot)org |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Trying to track down weird query stalls |
Date: | 2009-03-30 20:39:39 |
Message-ID: | 20090330203939.GF23023@alvh.no-ip.org |
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Thread: | |
Lists: | pgsql-performance |
dan(at)sidhe(dot)org escribió:
> where libinstance.libdate <= 1238445044
> and libinstance.enddate > 1238445044
> and libinstance.libinstanceid = libobject.libinstanceid
> and libinstance.architecture = ?
How are you generating the explain? My bet is that you're just
substituting a literal in the architecture condition, but if the driver
is smart then maybe it's preparating the query beforehand. You'll get a
different plan in that case. Try something like this:
prepare foo(smallint) as ...
where libinstance.architecture = $1
...
explain analyze execute foo(1);
If the plan you get from that is bad (and it often is), you should look
at avoiding a query prepare.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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