Re: Performance Tuning Document?

Alvaro Herrera wrote:
> El Mar 28, Bruce Momjian escribio:
>
> > Matthew Kirkwood wrote:
> > > Hi,
> > >
> > > I'm playing with OSDB (http://osdb.sf.net/) and trying to get
> > > the best numbers possible out of it.
>
> > > Any tips and tricks available? Thus far, I have tried:
> >
> > Gererally, I think 1/4 RAM for shared buffers is a good start, and
> > perhaps 2-4% for sort memory.
>
> That 2-4% means 2-4% per backend, or totalled? I don't have your
> experience, but I think that depends heavily on schemas and queries,
> more than shared buffers.

It is per-backend, and sort memory only helps for certain ORDER BY
queries or mergejoins that can't use an index. It is a very hard value
to set and usually is done to improve certain queries you can't fix
another way. However, the default is unusually small so it will work on
all machines so upping it isn't a major problem.

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