I don't THINK you have to recompile- I think Mark was on the right track. You can reset shmmax on Linux using the instructions in the "Linux" section of http://www.postgresql.org/docs/8.2/interactive/kernel-resources.html, and then you can bump up the Postgres shared_buffers setting.
Basically, the OS isn't allowing Postgres to start because Postgres is asking for too much memory. You need to tell the OS to allow processes to grab lots of memory, then tell Postgres to grab it. I did this recently on a CentOS machine. It was pretty easy and improved performance greatly. Good luck! -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Webb Sprague Sent: Wednesday, September 26, 2007 9:32 AM To: PostGIS Users Discussion Subject: Re: [postgis-users] postgis tuning parameters > > When performing complex queries, with thousands of records and > > geometries I am noticing that the postmaster process never exceeds 1% > > of my system's memory (2Gb). I have tried setting the shared_buffers > > parameter to values > 2000 ... but this only leads to an error when the > > postgres server is restarted: cannot allocate this much mem, check the > > SHMMAX kernel parameter. It sounds to me like you need to recompile Postgres with new values for SHMAX (and maybe other parameters too - I would ask on the Postgres General list). Building postgres is trivial, and if it is for a production machine it might be quite worthwhile -- there might be options for stripping debug symbols etc . -W > > > > Perhaps some answers on are this page: > > http://www.redhat.com/docs/manuals/database/RHDB-2.1-Manual/admin_user/ > > kernel-resources.html > > > > or in the minds of people on the list. The machine in question is > > mostly used for such queries and I would like postgis to be able to > > better utilize the resources available. > > > > Cheers, > > > > Dylan > > > Hi Dylan, > > Indeed, everything you need to know should be on that page - here is the > most recent version: > http://www.postgresql.org/docs/8.2/interactive/kernel-resources.html. > Experiment with different settings, but most people tend to recommend > about 25% of your available RAM (~60,000 buffers for 2Gb) for a > dedicated database server. > > > HTH, > > Mark. > > -- > ILande - Open Source Consultancy > http://www.ilande.co.uk > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
