Re: foreign data wrappers

On 03/24/2011 10:07 PM, Zheng Yang wrote:
>
>
> I've briefly gone through the slides. Regarding the 6 callbacks, is
> that correct to say that a full table scan will always be performed
> irregardless of the sql statement,
> the FDW is blind to the sql query performed, right?

Yes, fairly much. If the feed is large you need some way to pass a limit
to the foreign side, possibly via table options. I'm fairly sure you
won't be able to get it via the SELECT statement.

>
> And can anyone help explain what a planner is? What does this "provide
> cost estimates to planner" mean? Thanks!


See <http://www.postgresql.org/docs/current/static/planner-optimizer.html>

If you're going to work on PostgreSQL code you need to read the docs.

cheers

andrew