Re: ECPG FETCH readahead - Mailing list pgsql-hackers

From Michael Meskes
Subject Re: ECPG FETCH readahead
Date
Msg-id 20120416160448.GA9968@feivel.credativ.lan
Whole thread Raw
In response to Re: ECPG FETCH readahead  (Boszormenyi Zoltan <zb@cybertec.at>)
Responses Re: ECPG FETCH readahead  (Boszormenyi Zoltan <zb@cybertec.at>)
List pgsql-hackers
On Mon, Apr 16, 2012 at 06:24:57AM +0200, Boszormenyi Zoltan wrote:
> Yes, just like when the readahead window set to 256, FETCH 1024
> will iterate through 4 windows or FETCH 64 iterates through the
> same window 4 times. This is the idea behind the "readahead window".

Really? It's definitely not the idea behind FETCH 1024. Using the same window 4
times for FETCH 64 is the idea though, I agree.

> How about allowing the readahead window to be resized for the
> non-decorated case if the runtime encounters FETCH N and N is
> greater than the previous window?

To be resized by what? IMO a FETCH N should always be a FETCH N, no matter
what, i.e. if the readahead window is larger, use it, but even if it's smaller
we should still fetch N at the same time.

Michael

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