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Re: Slow query after upgrades

From: Albert László-Róbert <albertlaszlorobert(at)gmail(dot)com>
To: Tom Duffey <tduffey(at)techbydesign(dot)com>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: Slow query after upgrades
Date: 2007-12-14 08:55:16
Message-ID: 1197622516.6335.23.camel@albertlr-rss (view raw, whole thread or download thread mbox)
Lists: pgsql-jdbc
Hi All,

i have the same problem like above, with a little difference. i read all
the messages posted on this topic, and the symptoms were the same.

On Thu, 2007-12-13 at 15:15 -0600, Tom Duffey wrote:
> Hi All,
> We recently upgraded both our PostgreSQL server version (8.1.10 to  
> 8.2.5) and JDBC driver version (pg74.216.jdbc3, yeah, I know... to  

firstly we upgraded from version 8.1.2 (8.1 [i don't know the build
number] JDBC3 Driver) to 8.2.4 (initially we used the same driver and we
upgraded to the 8.2-507 JDBC3 driver) and we noticed this problem that
the queries that were using outer joins were slow. we find out that in
8.2.4 there was a problem with the optimization and the developers
advise to use the 8.2.5 ... so we upgraded the database to 8.2.5.
i must notice that before the database was running on a dual CPU server
with 2GB of memory ... the upgraded database was installed on a 4 CPU
system with 6 GB of memory ... so we expected some speed improvements
but we were disappointed.

> 8.2-507 JDBC4).  Our application has several components and all but 
> one are working great.  Unfortunately, one of them is running much  
> slower when I use the new JDBC driver.  If I leave everything else  
> exactly the same but roll back to the pg74.216.jdbc3 driver  

we do not tried this because we desperately needed the case sensitive
and case insensitive improvements of the LIKE and ILIKE operators on the
Unicode character set (UTF8-hu).

> performance improves quite a bit.  By quite a bit I mean a process  
> that takes about 15 minutes to run with the old JDBC driver takes over  
> an hour and a half with the new driver.

the performance before were arount 1-2 minutes ... and after the upgrade
it was about 30-40 minutes and more ... but because our application is
running throw the internet using the CORBA technology in most of the
cases the database throws an org.postgresql.util.PSQLException(: An I/O
error occured while sending to the backend.) exception.

> I'm leaving the old JDBC driver there for now but am wondering if  
> anyone has any ideas what I should look for to find a solution to  
> this?  I jProfiled the execution and it is indeed the JDBC query that  
> is taking significantly more time to execute with the newer driver in  
> place.
> Best Regards,
> Tom
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?

i hope this will help in the solving of the problem and maybe to get a
better suggestion to solve our problem.

sorry for my english ... i'm not native :)

László-Róbert, Albert
mobile: +40-(0)-742-874-854
office: +40-(0)-365-410-540
e-mail: albertlaszlorobert(at)gmail(dot)com

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Subject: Re: Slow query after upgrades
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