Thread: Bug in MERGE's test for tables with rules

While playing around with rules and MERGE, I noticed that there is a
bug in the way that it detects whether the target table has rules ---
it uses rd_rel->relhasrules, which can be incorrect, since it might be
set for a table that doesn't currently have rules, but did in the
recent past.

So it actually needs to examine rd_rules. Technically, I think that it
would be sufficient to just test whether rd_rules is non-NULL, but I
think it's more robust and readable to check rd_rules->numLocks, as in
the attached patch.

Regards,
Dean

Dean Rasheed <dean.a.rasheed@gmail.com> writes:
> While playing around with rules and MERGE, I noticed that there is a
> bug in the way that it detects whether the target table has rules ---
> it uses rd_rel->relhasrules, which can be incorrect, since it might be
> set for a table that doesn't currently have rules, but did in the
> recent past.

> So it actually needs to examine rd_rules. Technically, I think that it
> would be sufficient to just test whether rd_rules is non-NULL, but I
> think it's more robust and readable to check rd_rules->numLocks, as in
> the attached patch.

+1 for the code change.  Not quite sure the added test case is worth
the cycles.

            regards, tom lane

On Wed, 23 Nov 2022 at 15:32, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Not quite sure the added test case is worth the cycles.
>

No, probably not, for such a trivial change.

Pushed to HEAD and 15, without the test. Thanks for looking!

Regards,
Dean