Re: config problems

On Mon, 12 Nov 2001, Henk wrote:

> I have some problems configuring postgresql 7.0 .  I am using the rpms
> on a redhat 7.1 distribution.  I want to change the option -N to 64 and
> the -B to 128.  I put this in the postmaster.opts.default

I am not familiar with the way your distribution is setup, but in general
most "default" files are not meant to be used directly, but to be copied
without the "default". As far as I know the file postgresql looks for is
postmaster.opts.

> Also, what is the best way to make an estimation of the highest number
> of connections my system will be able to handle ?  (the server is a PIII
> 500MHz with 256MB RAM).

It has a lot to do with the type of queries that will be done against it.
For example if you have simple queries which get done under a second then
you would probably be able to handle lots of connections.

If you give the list more info on your expected type of usage we may be
able to better help you.

I am a newbie myself, but I think a general answer to how many connections
you can "possibly" support is determined by two issues:
-How many connections you allow on the postgresql.conf file
-How much memory each instance of postmaster takes. This depends on how
many buffers and other memory bound options you have set. For example if
each instance of postmaster takes 25MB and you have 100MB of memory
sitting around free then you can do 4 connections using "real memory".
This doesn't mean you can't have more connections, but you will start
going to swap space.

You can use top or ps to see how much memory an instance of postgreql
takes as you have it configured.

Please do remeber that I am a newbie myself and I may be unaware of memory
optimizations/sharing that postgresql may so you may actually get better
numbers than what I am discribing. Hopefully you will get other answers
from other with more experience.