| From: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
|---|---|
| To: | Zheng Yang <zhengyang4k(at)gmail(dot)com> |
| Cc: | Shiv <rama(dot)theone(at)gmail(dot)com>, Selena Deckelmann <selena(at)chesnok(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Guillaume Lelarge <guillaume(at)lelarge(dot)info>, pgsql-students <pgsql-students(at)postgresql(dot)org> |
| Subject: | Re: foreign data wrappers |
| Date: | 2011-03-26 15:07:17 |
| Message-ID: | 4D8E0125.9060905@dunslane.net |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general pgsql-students |
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
| From | Date | Subject | |
|---|---|---|---|
| Next Message | pasman pasmański | 2011-03-26 15:42:10 | Re: Out of memory |
| Previous Message | Shiv | 2011-03-26 12:48:48 | Re: foreign data wrappers |
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Zheng Yang | 2011-03-27 12:51:21 | Re: foreign data wrappers |
| Previous Message | Shiv | 2011-03-26 12:48:48 | Re: foreign data wrappers |