d844cd75a and postgres_fdw

Devrim GÜNDÜZ <devrim@gunduz.org>

From: Devrim Gündüz <devrim@gunduz.org>
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-10-24T11:46:40Z
Lists: pgsql-hackers

Attachments

Hi,

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?

Regards,

-- 
Devrim Gündüz
Open Source Solution Architect, PostgreSQL Major Contributor
Twitter: @DevrimGunduz , @DevrimGunduzTR

Commits

  1. postgres_fdw: Avoid "cursor can only scan forward" error.