Re: Prefetch children
От | Ioannis Theoharis |
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Тема | Re: Prefetch children |
Дата | |
Msg-id | Pine.GSO.4.58.0409210014420.5901@calliope обсуждение исходный текст |
Ответ на | Re: Prefetch children (Neil Conway <neilc@samurai.com>) |
Список | pgsql-general |
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?
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