Daniel,
> > I just wondered if there is a possibility to map my database running
> > on a linux system completly into memory and to only use disk
> > accesses for writes.
>
> That happens for free, if you have enough RAM. The kernel will use
> spare RAM to hold copies of every disk block it's ever read.
Also, don't forget to raise your effective_cache_size so that PostgreSQL
*knows* that you have lots of RAM.
--
Josh Berkus
Aglio Database Solutions
San Francisco