Re: sql/med review - problems with patching

On Tue, Jul 20, 2010 at 11:40:18AM +0200, Pavel Stehule wrote:
> 2010/7/20 Itagaki Takahiro <itagaki(dot)takahiro(at)gmail(dot)com>:
> > 2010/7/14 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>:
> >> please, can you refresh patch, please?
> >
> > Updated patch attached. The latest version is always in the git
> > repo. http://repo.or.cz/w/pgsql-fdw.git   (branch: fdw) I'm
> > developing the patch on postgres' git repo. So, regression test
> > for dblink might fail because of out-of-sync issue between cvs and
> > git.
> >
> >> When I looked to documentation I miss a some tutorial for foreign
> >> tables. There are only reference. I miss some paragraph where is
> >> cleanly and simple specified what is possible now and whot isn't
> >> possible. Enhancing of dblink isn't documented
> >
> > Sure. I'll start to write documentation when we agree the design
> > of FDW.
> >
> >> In function  pgIterate(ForeignScanState *scanstate) you are
> >> iterare via pg result. I am thinking so using a cursor and
> >> fetching multiple rows should be preferable.
> >
> > Sure, but I'm thinking that it will be improved after libpq
> > supports protocol-level cursor. The libpq improvement will be
> > applied much more applications including postgresql_fdw.
> >
>
> is there some time frame for this task - or ToDo point? Minimally it
> has to be documented, because it can be a issue on larger sets -
> speed, memory usage. I am afraid about speed for queries like
>
> select * from large_dblink_tab limit 100;

The general issue of passing qualifiers to the remote data source is
complex, especially when the DML for that data source is different
from PostgreSQL's DML.

Do you have some ideas as to how to solve this problem in general? In
this case?

Cheers,
David.
--
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