On Mon, May 15, 2017 at 3:22 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Jeff Janes <jeff.janes@gmail.com> writes: > I've tried versions 9.6.3 and 10dev, and neither do what I expected. It > doesn't seem to be a planning problem where it thinks the fast plan is > slower, it just doesn't seem to consider the faster plans as being options > at all. Is there some setting to make it realize the cast is shippable?
AFAICS, postgres_fdw doesn't have any knowledge of CoerceViaIO parse nodes, so it's never going to consider this type of brute-force cast as shippable. Normal casts would presumably be shippable if the underlying function is considered safe.
So then, the secret is to write it like this:
explain analyze select data from remote2 join remote1 on (int8in(textout(remote2.id)) = remote1.id)
where cutoff > 0.9999;
This works to have the join pushed to the foreign side in 9.6, but not before that.
