From: Claus Guttesen <kometen@gmail.com>
To: Faludi Gábor <gfaludi@fits.hu>
Cc: pgsql-performance@postgresql.org
Subject: Re: how does pg handle concurrent queries and same queries
Date: Mon, 28 Jul 2008 08:55:53 +0200
Message-ID: <b41c75520807272355m28a5f111re80e17f70ef7d87c@mail.gmail.com> (raw)
In-Reply-To: <000301c8f07d$4bee0f10$e3ca2d30$@hu>
References: <000301c8f07d$4bee0f10$e3ca2d30$@hu>
> I have taken over the maintenance of a server farm , recently. 2 webserver
> on db server. They are quite powerful 2 processor xeon w/ 6Gig of ram .
>
> Couple of days ago we had a serious performance hit and the db server (pg.
> v7.4) was overloaded w/ something in a way that operating system was almost
> not able to respond or in cases it did not.
>
> After some analysis i suspect that there is a query that takes up to 1
> second and that is the cause. Upon each page loading this query fires and
> takes the one second and blocks the page to load completly . The load was
> roughly ~300 connections in one minute .
>
> So here are my questions :
>
> · Why does the second and the later queries take the whole on second
> if the dataset is the same . Shouldn't PG realise that the query is the same
> so i give the user the same resultset ?
>
> · How do I know if one query blocks the other ?
>
> · Is there a way to log the long running queries in 7.4 ? If not is
> it available in any newer version ?
Can you post the queries? Can you provide an 'analyze explain'? Do you
perform a 'vacuum analyze' on a regular basis?
--
regards
Claus
When lenity and cruelty play for a kingdom,
the gentlest gamester is the soonest winner.
Shakespeare
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To: pgsql-performance@postgresql.org
Cc: kometen@gmail.com, gfaludi@fits.hu
Subject: Re: how does pg handle concurrent queries and same queries
In-Reply-To: <b41c75520807272355m28a5f111re80e17f70ef7d87c@mail.gmail.com>
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