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Re: Libpq Asynchronous Command Processing

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On 31/05/2010 5:41 PM, Giles Lean wrote:
=?iso-8859-1?Q?Alonso_Garc=EDa_=2C_Bruno_Elier?=<bealonso@xxxxxxxx>  wrote:

And the problems I am finding are the following:
->Queries from the client to the new DB server take a lot of time.
->Queries from the client to the old DB server are fast.
->The same query takes 150 secs in one case an 1 sec in the other case.

With that analysis, I'd be betting against it being a client problem.
(If you wanted, you might confirm that by pointing an old client at
the new server.)

I'd look into how the data was loaded into the new server and how
the database is configured: number of buffers, indexes, and whether
analyze has been run or not.

It would be strange indeed (possible, but very strange) to find
such a slowdown between 7.x and 8.x when the team is preparing
to push 9.0 out the door.  Surely it would have been known before;
therefore it's a practical certatinty that there is something
different about the configuration of your two servers.

... or that the planner is making a bad choice when it made a good one in 7.x . That's far from unheard of; the downside of a stats-based and very complex planner is that sometimes it doesn't make the perfect choice. Even with the same stats, etc, it's far from impossible that 7.x might hit a good plan when 8.x doesn't.

I mention this because the OP really needs to supply EXPLAIN ANALYZE results for the query run via psql (not their custom code) on both their 7.x and 8.x servers.

--
Craig Ringer

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