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* 99% time spent in WAL wait events
@ 2017-10-16 13:34 Purav Chovatia <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: Purav Chovatia @ 2017-10-16 13:34 UTC (permalink / raw)
To: pgsql-performance
Hello,
We are running workload on a EDB Postgres Advanced Server 9.6 and we see
that 99% of the time is spent on WAL wait events:
*System Wait Information WAIT NAME COUNT WAIT TIME % WAIT
---------------------------------------------------------------------------
wal flush 564552 298.789464 41.67 wal write 521514 211.601124 29.51 wal
file sync 521546 205.519643 28.66*
Disk IO performance is not an issue and WAL is on a dedicated disk.
Can somebody pls suggest if there is any possibility to improve this & how?
We already tried wal_buffers=96m, wal_sync_method=open_sync/open_datasync,
checkpoint_completion_target=0.9 but none of those helped.
System has 32GB RAM and shared_buffers=8GB. All transactions are happening
on a single table which has about 1.5m records and the table size is 1.7GB
with just one PK index.
Many Thanks
Regards
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: 99% time spent in WAL wait events
@ 2017-10-16 15:31 Purav Chovatia <[email protected]>
parent: Purav Chovatia <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Purav Chovatia @ 2017-10-16 15:31 UTC (permalink / raw)
To: pgsql-performance
Kindly ignore this post. It was an oversight - the wait times are in
millisec and hence even if we manage to reduce these waits to 0, we will
gain only 1000 msec of savings during a workload of 40min.
Regards
On 16 Oct 2017 7:04 pm, "Purav Chovatia" <[email protected]> wrote:
Hello,
We are running workload on a EDB Postgres Advanced Server 9.6 and we see
that 99% of the time is spent on WAL wait events:
*System Wait Information WAIT NAME COUNT WAIT TIME % WAIT
---------------------------------------------------------------------------
wal flush 564552 298.789464 41.67 wal write 521514 211.601124 29.51 wal
file sync 521546 205.519643 28.66*
Disk IO performance is not an issue and WAL is on a dedicated disk.
Can somebody pls suggest if there is any possibility to improve this & how?
We already tried wal_buffers=96m, wal_sync_method=open_sync/open_datasync,
checkpoint_completion_target=0.9 but none of those helped.
System has 32GB RAM and shared_buffers=8GB. All transactions are happening
on a single table which has about 1.5m records and the table size is 1.7GB
with just one PK index.
Many Thanks
Regards
^ permalink raw reply [nested|flat] 2+ messages in thread
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