Re: [PERFORM] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb) - Mailing list pgsql-hackers

From Michael Clemmons
Subject Re: [PERFORM] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date
Msg-id 4427a97a0912281904qc90817i4edd6852b26dde7f@mail.gmail.com
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In response to Re: [PERFORM] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund <andres@anarazel.de>)
Responses Re: [PERFORM] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
Maybe not crash out but in this situation.
N=0
while(N>=0):
    CREATE DATABASE new_db_N;
Since the fsync is the part which takes the memory and time but is happening in the background want the fsyncs pile up in the background faster than can be run filling up the memory and stack.
This is very likely a mistake on my part about how postgres/processes actually works.
-Michael

On Mon, Dec 28, 2009 at 9:55 PM, Andres Freund <andres@anarazel.de> wrote:
On Tuesday 29 December 2009 03:53:12 Michael Clemmons wrote:
> Andres,
> Great job.  Looking through the emails and thinking about why this works I
> think this patch should significantly speedup 8.4 on most any file
> system(obviously some more than others) unless the system has significantly
> reduced memory or a slow single core. On a Celeron with 256 memory I
>  suspect it'll crash out or just hit the swap  and be a worse bottleneck.
>  Anyone have something like this to test on?
Why should it crash? The kernel should just block on writing and write out the
dirty memory before continuing?
Pg is not caching anything here...

Andres

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