Re: [ADMIN] shared_buffers and shmmax

Bruce Momjian wrote:
> Tom Lane wrote:
> > [ redirecting to pgsql-docs ]
> >
> > Valentin Bogdanov <valiouk@yahoo.co.uk> writes:
> > >> From: dx k9 <bitsandbytes88@hotmail.com>
> > >> I'm trying to understand what the documentation means
> > >> by bytes per increment, what is the increment supposed to
> > >> be bytes, MB, or Kb.
> >
> > > shared_buffers is in disk block size, typically 8K, at least that's what it is on Linux platforms. shmmax is
quitesimply in bytes. 
> >
> > The table the OP is looking at (table 17.2 in the 8.3 docs) predates
> > the ability to specify shared_buffers in KB or MB instead of
> > number-of-buffers.  I agree it's not entirely obvious that what it
> > means is "multiply your setting in KB/MB by 8400/8192".  Anybody have
> > an idea how to clarify things?
>
> I have updated the table title to be clearer.

I don't find it any clearer ... I think the missing clue is that if you
specify shared_buffers values in MB, you must divide the value by block
size.


> ***************
> *** 1119,1125 ****
>
>         <row>
>          <entry>Fixed space requirements</>
> !        <entry>770 kB</entry>
>         </row>
>        </tbody>
>       </tgroup>
> --- 1119,1125 ----
>
>         <row>
>          <entry>Fixed space requirements</>
> !        <entry>770 k</entry>
>         </row>
>        </tbody>
>       </tgroup>

This change is wrong, why did you do it?

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support