Re: slow dropping of tables, DropRelFileNodeBuffers, tas

From: Sergey Koposov <koposov(at)ast(dot)cam(dot)ac(dot)uk>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: slow dropping of tables, DropRelFileNodeBuffers, tas
Date: 2012-06-01 11:34:19
Message-ID: alpine.LRH.2.02.1206011107001.26221@calx046.ast.cam.ac.uk
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On Fri, 1 Jun 2012, Simon Riggs wrote:

>
> Why do you have 10,000 tables and why is it important to drop them so quickly?

10000 tables are there, because that's the number of partitions. And I'm
dropping them at the moment, because I'm doing testing. So it won't be
really crucial for production. But I still thought it was worth reporting.
Especially when the table dropping took .5 a sec.

The problem is that when I set up the shared_buffers say to 48G, the
timings of the tables rise significantly again.

> If its that important, why not run the drop in parallel sessions?

Yes, before there was a strong reason to do that, now the timings are more
manageable, but maybe I'll implement that.

Cheers,
S

*****************************************************
Sergey E. Koposov, PhD, Research Associate
Institute of Astronomy, University of Cambridge
Madingley road, CB3 0HA, Cambridge, UK
Tel: +44-1223-337-551 Web: http://www.ast.cam.ac.uk/~koposov/

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