Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade

From: Matthew Hall <mhall(at)mhcomputing(dot)net>
To: "Henrik Cednert (Filmlance)" <henrik(dot)cednert(at)filmlance(dot)se>
Cc: "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org>
Subject: Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
Date: 2017-11-22 19:52:11
Message-ID: ADC5D88A-5486-4075-B99F-80102F6DA681@mhcomputing.net
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On Nov 22, 2017, at 5:06 AM, Henrik Cednert (Filmlance) <henrik(dot)cednert(at)filmlance(dot)se> wrote:
>
> When investigating the zlib lead I looked at 8.4 installation and 9.5 installation. 9.5 includes zlib.h (/Library/PostgreSQL//9.5/include/zlib.h), but 8.4 doesn't. But that's a header file and I have no idea how that really works and if that's the one used by pgres9.5 or not. The version in it says 1.2.8 and that's what the Instruments are showing when I monitor pg_dump while running.
>
> Guess I'll have to install instruments in a dev env and do a pg_dump with 8.4 to see the difference. Tedious. =/

I would also check the library linkages of the pg_dump binaries.

See if one thing is using an embedded zlib and the other a system zlib.

Then you could imagine one didn't get compiled with the best-performing CFLAGS, etc.

Matthew.

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