From: | Rob Gansevles <rgansevles(at)gmail(dot)com> |
---|---|
To: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Reusing cached prepared statement slow after 5 executions |
Date: | 2011-06-26 14:52:33 |
Message-ID: | BANLkTikJo6FAGMnukSm+C4rtApO9Kam_ig@mail.gmail.com |
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Lists: | pgsql-general |
Hi,
I came across a strange issue when caching prepared statement..
We are accessing postgres(9.0.3) via the jdbc driver (9.0b801) using a
prepared statement cache.
This works very good but in 1 case the 5th execution (and later ones)
suddenly takes 30 seconds as the first few just take less then 1 sec.
When I disable prepared statement caching all executions are fast.
The query is:
select 1 from asiento left outer join asiento_cab
on asiento.asiento_cab_id=asiento_cab.asiento_cab_id where asiento_cab.anio = ?
and asiento_cab.mes between ? and ?
and asiento.aux_cuenta between ? and ?
and asiento.hija = ?
Each execution has the same input parameters.
When I remove any of the conditions in the query, all executions are
of the same speed.
Has anyone seen this behaviour before?
When the slow query runs, i see a 100% cpu usage of the postgres
process, so I guess this would be an issue with the engine.
But I can only reproduce this with the jdbc driver and reuse a
prepared statement.
So when filing a bug, against what should be bug be filed, the engine
or the driver?
Thanks for any comments,
Rob
PS (sorry about my prev email, it got sent incomplete)
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