> > I have a postgresql 7.4.8-server with 4 GB ram. > > #effective_cache_size = 1000 # typically 8KB each > > > > This is computed by sysctl -n vfs.hibufspace / 8192 (on FreeBSD). So I > > changed it to: > > > > effective_cache_size = 27462 # typically 8KB each > > Apparently this formula is no longer relevant on the FreeBSD systems as > it can cache up to almost all the available RAM. With 4GB of RAM, one > could specify most of the RAM as being available for caching, assuming > that nothing but PostgreSQL runs on the server -- certainly 1/2 the RAM > would be a reasonable value to tell the planner. > > (This was verified by using dd: > dd if=/dev/zero of=/usr/local/pgsql/iotest bs=128k count=16384 to create > a 2G file then > dd if=/usr/local/pgsql/iotest of=/dev/null > > If you run systat -vmstat 2 you will see 0% diskaccess during the read > of the 2G file indicating that it has, in fact, been cached)
Thank you for your reply. Does this apply to FreeBSD 5.4 or 6.0 on amd64 (or both)? regards Claus ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
