From: Heikki Linnakangas <hlinnakangas@vmware.com>
To: Markus Schulz <msc@antzsystem.de>
Cc: pgsql-performance@postgresql.org
Subject: Re: BUG: endless lseek(.., SEEK_END) from select queries on x64 builds
Date: Sat, 23 Feb 2013 17:54:26 +0200
Message-ID: <5128E632.2040209@vmware.com> (raw)
In-Reply-To: <201302221910.25271.msc@antzsystem.de>
References: <201302220925.26460.msc@antzsystem.de>
<5127741D.6090907@vmware.com>
<201302221910.25271.msc@antzsystem.de>
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On 22.02.2013 20:10, Markus Schulz wrote:
> Am Freitag, 22. Februar 2013, 14:35:25 schrieb Heikki Linnakangas:
>> You could check what the generic plan looks like by taking the query
>> used in the java program, with the parameter markers, and running
>> EXPLAIN on that.
>
> how can i do this?
> I've tried the following in my ejb-test-function to:
>
> String query = "..."
> entitymanager.createNativeQuery(query)...;
> entitymanager.createNativeQuery("EXPLAIN ANALYZE " + query)...;
>
> but the second createNativeQuery call runs fast every time and will show the
> same plan and the first hangs after the fourth call to this function.
You can take the query, replace the ? parameter markers with $1, $2, and
so forth, and explain it with psql like this:
prepare foo (text) as select * from mytable where id = $1;
explain analyze execute foo ('foo');
On 9.2, though, this will explain the specific plan for those
parameters, so it might not be any different from what you already
EXPLAINed.
- Heikki
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To: pgsql-performance@postgresql.org
Cc: hlinnakangas@vmware.com, msc@antzsystem.de
Subject: Re: BUG: endless lseek(.., SEEK_END) from select queries on x64 builds
In-Reply-To: <5128E632.2040209@vmware.com>
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