On Fri, Jul 5, 2024 at 9:56 PM Etsuro Fujita <etsuro.fuj...@gmail.com> wrote: > On Tue, Oct 24, 2023 at 8:48 PM Devrim Gündüz <dev...@gunduz.org> wrote: > > I'm seeing an issue after upgrading from 12.13 to 15.4. This happens > > when we run a query against a foreign table (fdw on the same instance to > > a different database) -- but does not appear when we get rid of > > postgres_fdw: > > > > ERROR: cursor can only scan forward > > HINT: Declare it with SCROLL option to enable backward scan. > > CONTEXT: remote SQL command: MOVE BACKWARD ALL IN c1 > > > > SQL state: 55000 > > > > I attached the query. The name of the foreign table is > > "foobar.sys_user". > > > > Looks like the bug #17889, and this is the last email in that thread: > > https://www.postgresql.org/message-id/1852635.1682808624%40sss.pgh.pa.us > > > > OTOH, same query works (against the FDW) when we remove the following > > WHERE clause: > > > > WHERE > > tbl.table_status = 'A' > > AND tbl.table_id <> 1 > > AND tbl.table_id <> - 2 > > > > Any hints? > > The error occurs when rescanning a postgres_fdw foreign relation, so I > think the reason why the query works would be that the planner chose a > join plan other than a nestloop join plan. > > I proposed a fix for this in [1].
I pushed the fix and back-patched to v15. Thanks for the report! Best regards, Etsuro Fujita
