| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Rahila Syed <rahilasyed90(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [REVIEW] Re: Compression of full-page-writes |
| Date: | 2014-12-12 16:12:10 |
| Message-ID: | 20141212161210.GD8139@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
On 2014-12-12 11:08:52 -0500, Robert Haas wrote:
> Unless I'm missing something, this test is showing that FPW
> compression saves 298MB of WAL for 17.3 seconds of CPU time, as
> against master. And compressing the whole record saves a further 1MB
> of WAL for a further 13.39 seconds of CPU time. That makes
> compressing the whole record sound like a pretty terrible idea - even
> if you get more benefit by reducing the lower boundary, you're still
> burning a ton of extra CPU time for almost no gain on the larger
> records. Ouch!
Well, that test pretty much doesn't have any large records besides FPWs
afaics. So it's unsurprising that it's not beneficial.
Greetings,
Andres Freund
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