From: Tom Lane <tgl@sss.pgh.pa.us>
To: Henrik Cednert (Filmlance) <henrik.cednert@filmlance.se>
Cc: pgsql-performance@lists.postgresql.org <pgsql-performance@lists.postgresql.org>
Subject: Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
Date: Tue, 21 Nov 2017 16:01:20 -0500
Message-ID: <20863.1511298080@sss.pgh.pa.us> (raw)
In-Reply-To: <2D863ADA-134E-414B-82DD-88E53D621697@filmlance.se>
References: <8F33D0C7-E12E-4996-990C-3CF0C5ED0437@filmlance.se>
<7442.1511283687@sss.pgh.pa.us>
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<14231.1511289969@sss.pgh.pa.us>
<2D863ADA-134E-414B-82DD-88E53D621697@filmlance.se>
"Henrik Cednert (Filmlance)" <henrik.cednert@filmlance.se> writes:
> I'm not sure if I can attach screenshots here. Trying, screenshot from instruments after running for a few mins.
It looks like practically all of pg_dump's time is going into deflate(),
ie zlib. I don't find that terribly surprising in itself, but it offers
no explanation for why you'd see a slowdown --- zlib isn't even our
code, nor has it been under active development for a long time, so
presumably 8.4 and 9.5 would have used the same version. Perhaps you
were doing the 8.4 dump without compression enabled?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, henrik.cednert@filmlance.se, pgsql-performance@lists.postgresql.org
Subject: Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
In-Reply-To: <20863.1511298080@sss.pgh.pa.us>
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