Re: Push down more full joins in postgres_fdw

On Mon, Dec 5, 2016 at 6:20 AM, Ashutosh Bapat
<ashutosh.bapat@enterprisedb.com> wrote:
> 4. I am still not happy with this change
> +        /*
> +         * Since (1) the expressions in foreignrel's reltarget doesn't contain
> +         * any PHVs and (2) foreignrel's local_conds is empty, the tlist
> +         * created by build_tlist_to_deparse must be one-to-one with the
> +         * expressions.
> +         */
> +        Assert(list_length(tlist) ==
> list_length(foreignrel->reltarget->exprs));
> the assertion only checks that the number of elements in both the lists are
> same but does not check whether those lists are same i.e. they contain the same
> elements in the same order. This equality is crucial to deparsing logic. If
> somehow build_tlist_to_deparse() breaks that assumption in future, we have no
> way to detect it, unless a regression test fails.

If there's an easy way to do a more exact comparison, great.  But if
we can't get an awesome Assert(), a helpful Assert() is still better
than a kick in the head.

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