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From: dan@sidhe.org
To: Alvaro Herrera <alvherre@commandprompt.com>
Cc: dan@sidhe.org,"Robert Haas" <robertmhaas@gmail.com>
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Trying to track down weird query stalls
Date: Mon, 30 Mar 2009 17:07:36 -0400 (EDT)
Message-ID: <51413.199.172.169.17.1238447256.squirrel@localhost> (raw)
In-Reply-To: <20090330210022.GG23023@alvh.no-ip.org>
References: <603c8f070903301131p8086067ob552d09e8b21c82@mail.gmail.com>
	<56921.199.172.169.36.1238438533.squirrel@localhost>
	<dcc563d10903301238u135d82bpf498c2d40ac31977@mail.gmail.com>
	<57654.199.172.169.17.1238442145.squirrel@localhost>
	<dcc563d10903301247t58bef7cbsd0b6d3bbd1a5e046@mail.gmail.com>
	<56164.199.172.169.17.1238443348.squirrel@localhost>
	<603c8f070903301313u1a9606a3m27da187b5e376785@mail.gmail.com>
	<56504.199.172.169.35.1238445194.squirrel@localhost>
	<20090330203939.GF23023@alvh.no-ip.org>
	<61646.199.172.169.32.1238446195.squirrel@localhost>
	<20090330210022.GG23023@alvh.no-ip.org>

> dan@sidhe.org escribió:
>> > dan@sidhe.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.
>>
>> I don't think so. Perl's DBI is involved, but the statement's in a
>> variable.
>
> So what's the "?" in the query you pasted earlier?

The first ? (for architecture) is 1, the second ? (for branchid) is 0.
They both should get passed to Postgres as $1 and $2, respectively,
assuming DBD::Pg does its substitution right. (They're both supposed to go
in as placeholders)

-Dan



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