On 02/26/2004-11:16AM, Dror Matalon wrote:
> >
> > effective_cache_size changes no cache settings for postgresql, it simply
> > acts as a hint to the planner on about how much of the dataset your OS /
> > Kernel / Disk cache can hold.
>
> I understand that. The question is why have the OS, in this case FreeBsd
> use only 200 Megs for disk cache and not more. Why not double the
> vfs.hibufspace to 418119680 and double the effective_cache_size to 51040.
>
FreeBSD uses ALL ram that isn't being used for something else as
its disk cache. The "effective_cache_size" in the PostGreSQL config
has no effect on how the OS chooses to use memory, it is just hint
to the PostGreSQL planner so it can guess the the likelyhood of
what it is looking for being in the cache.