Re: Where is my bottleneck?

On Tue, Jan 24, 2006 at 07:40:22PM +0100, Arnau Rebassa Villalonga wrote:
> Hi all,
>
> I have a performance problem and I don't know where is my bottleneck.
> I have postgresql 7.4.2 running on a debian server with kernel

You should really upgrade to the latest 7.4 version. You're probably
vulnerable to some data-loss issues.

> 2.4.26-1-686-smp with two Xeon(TM) at 2.80GHz and 4GB of RAM and a RAID
> 5 made with SCSI disks. Maybe its not the latest hardware but I think

Generally speaking, databases (or anything else that does a lot of
random writes) don't like RAID5.

> My problem is that the general performance is not good enough and I
> don't know where is the bottleneck. It could be because the queries are
> not optimized as they should be, but I also think it can be a postgresql
> configuration problem or hardware problem (HDs not beeing fast enough,
> not enough RAM, ... )

What kind of performance are you expecting? What are you actually
seeing?

> The configuration of postgresql is the default, I tried to tune the
> postgresql.conf and the results where disappointing, so I left again the
> default values.

Probably not so good... you'll most likely want to tune shared_buffers,
sort_mem and effective_cache_size at a minimum. Granted, that might not
be your current bottleneck, but it would probably be your next.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461