Re: [HACKERS] Varying results when using merge joins over postgres_fdw vs hash joins - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] Varying results when using merge joins over postgres_fdw vs hash joins
Date
Msg-id 5885.1505923600@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] Varying results when using merge joins overpostgres_fdw vs hash joins  (Peter Geoghegan <pg@bowt.ie>)
Responses Re: [HACKERS] Varying results when using merge joins overpostgres_fdw vs hash joins
Re: [HACKERS] Varying results when using merge joins overpostgres_fdw vs hash joins
List pgsql-hackers
Peter Geoghegan <pg@bowt.ie> writes:
> I think that Corey describes a user hostile behavior. I feel that we
> should try to do better here.

It is that.  I'm tempted to propose that we invent some kind of "unknown"
collation, which the planner would have to be taught to not equate to any
other column collation (not even other instances of "unknown"), and that
postgres_fdw's IMPORT ought to label remote columns with that collation
unless specifically told to do otherwise.  Then it's on the user's head
if he tells us to do the wrong thing; but we won't produce incorrect
plans by default.

This is, of course, not at all a back-patchable fix.
        regards, tom lane


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: [HACKERS] Varying results when using merge joins over postgres_fdw vs hash joins
Next
From: Masahiko Sawada
Date:
Subject: [HACKERS] Assertion failure when the non-exclusive pg_stop_backup aborted.