Re: VACUUM delay (was Re: What's planned for 7.5?)

People,

> I don't have the time to make enough different attempts to find the one
> that pleases all. My argument still is that all this IO throttling and
> IO optimizing is mainly needed for dedicated servers, because I think
> that if you still run multiple services on one box you're not really in
> trouble yet. So in the first round a configurable sync() approach would
> do. So far nobody even agreed to that.

I won't claim expertise on the different sync algorithms. However, I do need
to speak up in support of Jan's assertion; the machines most likely to suffer
I/O choke are, or should be, dedicated machines. If someone's running 6
major server applications on a server with a 25GB database and a single
RAID-5 array, then they've got to expect some serious performance issues.

We currently have a lot of users running large databases on devoted servers,
though, and they can't vaccuum their databases during working hours because
the vacuum ties up the I/O for 10 minutes or more. It's a bad situation and
makes us look very bad in comparison to the proprietary databases, which have
largely solved this problem. Maybe the sync() approach isn't perfect, but
it's certainly better than not doing anything, particularly if it can be
turned off at startup time.

--
-Josh Berkus
Aglio Database Solutions
San Francisco