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

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От Henrik Cednert (Filmlance)
Тема Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
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Msg-id 13B8A868-BB94-4A4B-81AF-EB3DCC379439@filmlance.se
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Ответ на Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
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Hi Tom

I'm honestly not sure about anything. =) I use the exact same flags as with 8.4 for the dump:

${BINARY_PATH}/pg_dump --host=localhost --user=postgres --no-password --blobs --format=custom --verbose --file=${pg_dump_filename}_${database}.backup ${database} 

So unless the default behaviour have changed in 9.x I'd say I don't use compression. I will try to force it to no compression and see if it's different.

Sadly the instruments session stopped recording when I logged out of the system yesterday. Doh. =/

Cheers

--
Henrik Cednert
cto | compositor

Filmlance International
mobile [ + 46 (0)704 71 89 54 ]
skype  [ cednert ]

On 21 Nov 2017, at 22:01, Tom Lane <tgl@sss.pgh.pa.us> wrote:

"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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