Re: SELECT constant; takes 15x longer on 9.0?

From: Merlin Moncure <mmoncure(at)gmail(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: SELECT constant; takes 15x longer on 9.0?
Date: 2010-04-06 13:07:06
Message-ID: q2pb42b73151004060607p5150565fl53d07782ed732daf@mail.gmail.com
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On Tue, Apr 6, 2010 at 1:47 AM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> Hackers,
>
> Continuing the performance test:
>
> DBD, like a number of monitoring systems, does "pings" on the database
> which look like this:
>
> SELECT 'DBD::Pg ping test';
>
> In our test, which does 5801 of these pings during the test, they take
> an average of 15x longer to execute on 9.0 as 8.4 ( 0.77ms vs. 0.05ms ).

did your pings change? on my machine the query ';' completes in about
0.05ms but any select takes 0.19 - 0.25ms.

0.77 is awfully high -- there has to be an explanation.

merlin

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