Re: shared_buffers in 8.3 w/ lots of RAM on dedicated PG machine

[Josh Berkus <josh(at)agliodbs(dot)com>]

On Friday 15 February 2008 06:29, Greg Smith wrote:
> PostgreSQL only uses direct I/O for writing to the WAL; everything else
> goes through the regular OS buffer cache unless you force it to do
> otherwise at the OS level (like some Solaris setups do with
> forcedirectio).

Also, note that even when direct I/O is available, most users and benchmark 
tests have reported that having PostgreSQL "take over" the entire cache is 
not a net performance gain.  I believe this is mostly because our I/O and 
caching code aren't designed for this kind of operation.

I believe that MyEmma had a different experience on their workload, though. 

-- 
Josh Berkus
PostgreSQL @ Sun
San Francisco