Re: postgres on apple OS X server

On Tue, 9 Mar 2004, Mira Kaloper wrote:

> Hi,
>
> I have a postgres database that is VERY slow - in one table we have 50
> mil records in it.
> I have tried to play with postgres.conf file and shared memory but was
> not able to speed it up to something that we can work with. We have
> apple RAID and I am planning to take database to the raid. I was
> wondering if someone has any hints about improving the speed on postgres.
>
> Currently we have:
> shmall = 134217728
> shmmax = 134217728
>
> and in postgresql.conf  I was setting up values to:
> shared_buffers = 15200
> sort_mem = 32168

There are a few areas here.

One, is database tuning:

http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html

The next is query tuning.  Use explain analyze select <rest of query>...
to see what is taking the longest, and if any of the estimates for rows
are way off from actual.  Further, check for things like mismatched FK
relationships (i.e. a text field fking to an int field).   Lastly, make
sure you're analyzing your data, and that you've vacuumed the database
lately.  You may need a vacuum full if you've waited a long time since the
last vacuum.

The next issue is your hardware.  There has been another report here on
OSX performing pretty poorly, especially disappointing were the results
with apple's XRAID product, which was running about 2/3 as fast as was
advertised.

You might want to post the output of explain analyze of one of the slow
queries.  The best list for this stuff is pgsql-perform..