Re: Recovery performance of DROP DATABASE with many tablespaces

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: "Jamison, Kirk" <k(dot)jamison(at)jp(dot)fujitsu(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Recovery performance of DROP DATABASE with many tablespaces
Date: 2018-09-30 12:51:30
Message-ID: 20180930125129.GE1763@paquier.xyz
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On Tue, Jul 10, 2018 at 03:04:05PM +0900, Michael Paquier wrote:
> It would be simple to measure the time it takes to replay this single
> DROP DATABASE record by putting two gettimeofday() calls or such things
> and then take the time difference. There are many methods that you
> could use here, and I suppose that with a shared buffer setting of a
> couple of GBs of shared buffers you would see a measurable difference
> with a dozen of tablespaces or so. You could also take a base backup
> after creating all the tablespaces, connect the standby and then drop
> the database on the primary to see the actual time it takes. Your patch
> looks logically correct to me because DropDatabaseBuffers is a
> *bottleneck* with large shared_buffers, and it would be nice to see
> numbers.

This was a couple of months ago, and nothing has happened since with the
patch waiting on author, so the patch is marked as returned with
feedback.
--
Michael

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