8.3 synchronous_commit

I might completely misunderstand this feature. Shouldn't
"synchronous_commit = off" improve performance?

Whatever I do, I find "synchronous_commit = off" to degrade performance.

Especially it doesn't like the CFQ I/O scheduler, it's not so bad with
deadline. Synthetic load like

pgbench -i -s 10 -U pgsql -d bench && pgbench -t 1000 -c 100 -U pgsql -d
bench

or the same with scale 100.

Maybe it's just my test box.. single SATA-II drive, XFS on top of LVM.

I'll retry without LVM once I have another drive.. I've seen LVM mess
with other things in the past.


--
Best regards,
Hannes Dorbath