Re: syncing with a MySQL DB

On Sun, Oct 26, 2008 at 12:41:39PM -0400, Jonah H. Harris wrote:
> On Sat, Oct 25, 2008 at 1:19 PM, Ernesto Quiñones <ernestoq@gmail.com> wrote:
> > I use dbi-link, work fine, but I have problems when I call mysql
> > tables "linked" and these tables are big, maybe a millon records,
> > the answers is really slow, I need to wait 5 or more minutes to
> > have an answer in a single query like this "select * from table
> > limit 10", I am thinking maybe dbi-link download all the data to
> > pgsql before to give me the answer.
>
> Yes, that's what Postgres is doing.  DBI-link is currently incapable
> of pushing down the predicate to the remote system because Postgres
> can't give it access to the predicate.

More precisely, Postgres is (as yet) incapable of giving DBI-Link the
information it needs.

> > Anybody knows how improve this?
>
> If I have to push the predicate down, I'll generally write a
> set-returning function which takes some of the predicate, limit, and
> offset info to build a dynamic sql query against the remote database
> using dblink.

That's one way.  For others, I can help out on a consulting basis :)

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter      XMPP: david.fetter@gmail.com

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