Re: Getting sorted data from foreign server for merge join

On Wed, Dec 2, 2015 at 6:45 AM, Rushabh Lathia <rushabh(dot)lathia(at)gmail(dot)com> wrote:
> Thanks Ashutosh.
>
> Re-reviewed and Re-verified the patch, pg_sort_all_pd_v5.patch
> looks good to me.

This patch needs a rebase.

It's not going to work to say this is a patch proposed for commit when
it's still got a TODO comment in it that obviously needs to be
changed. And the formatting of that long comment is pretty weird,
too, and not consistent with other functions in that same file (e.g.
get_remote_estimate, ec_member_matches_foreign, create_cursor).

Aside from that, I think before we commit this, somebody should do
some testing that demonstrates that this is actually a good idea. Not
as part of the test case set for this patch, but just in general.
Merge joins are typically going to be relevant for large tables, but
the examples in the regression tests are necessarily tiny. I'd like
to see some sample data and some sample queries that get appreciably
faster with this code. If we can't find any, we don't need the code.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company