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Re: "Mysterious" issues with newly installed 8.3

From: Craig James <craig_james(at)emolecules(dot)com>
To: Scott Carey <scott(at)richrelevance(dot)com>
Cc: Carlos Moreno <morenopg(at)mochima(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: "Mysterious" issues with newly installed 8.3
Date: 2008-10-10 02:45:25
Message-ID: 48EEC1C5.4090204@emolecules.com (view raw or flat)
Thread:
Lists: pgsql-performance
Scott Carey wrote:
> On Thu, Oct 9, 2008 at 4:51 PM, Carlos Moreno <morenopg(at)mochima(dot)com 
> <mailto:morenopg(at)mochima(dot)com>> wrote:
> 
> 
>     Ok, I know that such an open and vague question like this one
>     is...  well, open and vague...  But still.
> 
>     The short story:
> 
>     Just finished an 8.3.4 installation on a new machine, to replace
>     an existing one;  the new machine is superior (i.e., higher
>     performance) in virtually every way --- twice as much memory,
>     faster processor, faster drives, etc.
> 
>     I made an exact copy of the existing database on the new
>     machine, and the exact same queries run on both reveal that
>     the old machine beats the new one by a factor of close to 2 !!!!
>     (i.e., the same queries run close to twice as fast on the old
>     machine!!!)
> 
>     To make things worse:  the old machine is in operation, under
>     normal workload  (and right now the system may be around
>     peak time), and the new machine is there sitting doing nothing;
>     just one user logged in using psql to run the queries --- *no-one
>     and nothing* is connecting to the new server.
> 
>     So... What's going on???

Did you do an ANALYZE on the new database after you cloned it?  I was suprised by this too, that after doing a pg_dump/pg_restore, the performance sucked.  But it was simply because the new database had no statistics yet.

Craig

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Subject: Re: "Mysterious" issues with newly installed 8.3
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