Обсуждение: postgresql log indicate too many execute S_2:COMMIT

Hello:
    I test postgresql database performance recently,i set
log_min_duration_statement=1000;
i monitor pg_log file,i find too many execue S_2:commit
10.0.44.21:30170:2012-04-28 11:38:46.340 CSTLOG:  duration: 1050.679 ms
execute S_2: COMMIT

10.0.44.21:30208:2012-04-28 11:38:46.340 CSTLOG:  duration: 1050.576 ms
execute S_2: COMMIT

10.0.44.21:30318:2012-04-28 11:38:46.340 CSTLOG:  duration: 1028.171 ms
execute S_2: COMMIT

........

please explain what meaning,how to cause it ,how to deal with it?thank you !

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leo xu wrote:
>     I test postgresql database performance recently,i set
> log_min_duration_statement=1000;
> i monitor pg_log file,i find too many execue S_2:commit
> 10.0.44.21:30170:2012-04-28 11:38:46.340 CSTLOG:  duration: 1050.679
ms
> execute S_2: COMMIT
>
> 10.0.44.21:30208:2012-04-28 11:38:46.340 CSTLOG:  duration: 1050.576
ms
> execute S_2: COMMIT
>
> 10.0.44.21:30318:2012-04-28 11:38:46.340 CSTLOG:  duration: 1028.171
ms
> execute S_2: COMMIT
>
> ........
>
> please explain what meaning,how to cause it ,how to deal with it?thank
you !

It would be helpful to know *how* you test performance.
Also, the PostgreSQL version, operating system, software and hardware
configuration might be interesting.

If COMMIT takes a long time, my first guess would be that it takes a
long time to write the transaction log (the WAL files in pg_xlog) to
disk.

You can try to verify that with a disk performance measuring tool for
your operating system.

Yours,
Laurenz Albe

my postgres version is 9.1.2.my machine is dell R710.3000 sessions
connect to database concurrently,then doing some insert,delete,update.
     your meaning my database bottleneck is disk io slowly.i use local
disk.i know transaction log need to wirte to disk.
     thanks.i will monitor it.

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