Re: [sqlsmith] Failed assertion in joinrels.c

On Sun, Jun 5, 2016 at 12:29 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
>> This is still failing:
>> =# select indexdef from pg_catalog.pg_indexes where indexdef is not NULL;
>> ERROR: XX000: cache lookup failed for index 2619
>> LOCATION: pg_get_indexdef_worker, ruleutils.c:1054
>> Do we want to improve at least the error message?
>
> Maybe we should just make the function silently return NULL if the OID
> doesn't refer to an index relation. There's precedent for that sort
> of behavior ...

For views it is simply returned "Not a view", and for rules that's
"-". All the others behave like similarly to indexes:
=# select pg_get_constraintdef(0);
ERROR: XX000: cache lookup failed for constraint 0
=# select pg_get_triggerdef(0);
ERROR: XX000: could not find tuple for trigger 0
=# select pg_get_functiondef(0);
ERROR: XX000: cache lookup failed for function 0
=# select pg_get_viewdef(0);
pg_get_viewdef
----------------
Not a view
(1 row)
=# select pg_get_ruledef(0);
pg_get_ruledef
----------------
-
(1 row)

So yes we could just return NULL for all of them, or make them throw
an error. Anyway, my vote goes for a HEAD-only change, and just throw
NULL... This way an application still has the option to fallback to
something else with a CASE at SQL level without using plpgsql to catch
the error.

Also, I have not monitored the code much regarding some code paths
that rely on the existing rules, but I would imagine that there are
things depending on the current behavior as well.
--
Michael