Re: pgsql_fdw, FDW for PostgreSQL server

Shigeru Hanada <shigeru.hanada@gmail.com> writes:
> Thanks for the review.  Agreed to write own depraser for pgsql_fdw
> which handles nodes which can be pushed down.  Every SQL-based FDW
> which constructs SQL statement for each local query would need such
> module inside.

Yeah.  That's kind of annoying, and the first thing you think of is that
we ought to find a way to share that code somehow.  But I think it's
folly to try to design a shared implementation until we have some
concrete implementations to compare.  An Oracle FDW, for instance, would
need to emit SQL code with many differences in detail from pgsql_fdw.
It's not clear to me whether a shared implementation is even practical,
but for sure I don't want to try to build it before we've done some
prototype single-purpose implementations.
        regards, tom lane