On 7/29/05 6:23 AM, "Alvaro Herrera" <[EMAIL PROTECTED]> wrote:

> On Fri, Jul 29, 2005 at 03:01:07AM -0400, Luke Lonergan wrote:
>> I guess we see the real culprit here.  Anyone surprised it's the WAL?
> So what?  Are you planning to suggest people to turn fsync=false?

That's not the conclusion I made, no.  I was pointing out that fsync has a
HUGE impact on his problem, which implies something to do with the I/O sync
operations.  Black box bottleneck hunt approach #12.
> With fsync off, there's no
> work _at all_ going on, not just the WAL -- heap/index file fsync at
> checkpoint is also skipped.  This is no good.

OK - so that's what Tom is pointing out, that fsync impacts more than WAL.

However, finding out that fsync/no fsync makes a 400% difference in speed
for this problem is interesting and relevant, no?

- Luke

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