Re: Prefetch children

On Mon, 20 Sep 2004, Neil Conway wrote:

> On Sat, 2004-09-18 at 07:42, Ioannis Theoharis wrote:
> > I'd like to ask you,
> > if postgres prefetch child instances in memory ,
> > whenever a parent table is sequentially scanned,
> > in order to have them in there
> > for the possibility the next query to ask for them.
>
> I'm not sure exactly what you're asking (what do you mean by "child
> instances?"), but in any case, PostgreSQL doesn't do any prefetching
> ("readahead") -- we rely on the kernel to do that if and when it's
> appropriate.
>
> -Neil

I mean that i have a "tree" of tables, that has been created using
'inherits' relationship of postgress.

0
1 2
3 4 5 6

Consider this tree. In each node imagine a table. table no 1 inherits
table no 0, table no 3 inherits table 1 ...

The question is, if the table no 0 (root) is secuentially scanned, then
postgress, except from the contents of this table, loads in memory the
contents of tale no 1 or no 2 ?

If the answer is no, then what do you meen "we rely on the kernel to do
that if and when it's appropriate" ?
It's appropriate in my case?