Re: slow update of index during insert/copy

On Tue, 2 Sep 2008, Thomas Finneid wrote:

>> You should try setting this to open_sync , that can be considerably faster
>> for some write-heavy situations.  Make sure to test that throughly though,
>> there are occasional reports of issues with that setting under Linux
>
> The production machine is Solaris 10 running on a Sun v980. Do you know of it
> has any issues like these?

On Solaris you can safely use open_datasync which is a bit better than
open_sync.  For best results, you need to separate the xlog onto a
separate partition and mount it using forcedirectio, because Postgres
doesn't know how to use direct I/O directly on Solaris yet.

> Additionally, would I need to do any config changes when going from linux to
> solaris?

Assuming the same amount of memory, the postgresql.conf should be
basically the same, except for the wal_sync_method change mentioned above.
If there's more RAM in the production server you can ramp up
shared_buffers, effective_cache_size, and possibly work_mem
proportionately.  The settings I suggested for maintenance_work_mem and
wal_buffers are already near the useful upper limits for those parameters.

There are a few operating system level things you should consider tweaking
on Solaris 10 for better PostgreSQL performance.  You need to be a bit
more careful about the parameters used for the filesystem than on Linux,
and the settings there vary considerably depending on whether you're using
UFS or ZFS.  The best intro to that I know of is at
http://blogs.sun.com/jkshah/entry/postgresql_east_2008_talk_best ; I added
some clarification to a few points in there and some other Solaris notes
at http://notemagnet.blogspot.com/2008_04_01_archive.html  Those should
get you started.

I hope you're already looking into some sort of repeatable benchmarking
that's representative of your application you can run.  You'll go crazy
playing with all these settings without something like that.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD