Re: Getting fancy errors when accessing information_schema on 10.5 - Mailing list pgsql-admin

From Tom Lane
Subject Re: Getting fancy errors when accessing information_schema on 10.5
Date
Msg-id 20191.1540901834@sss.pgh.pa.us
Whole thread Raw
In response to Re: Getting fancy errors when accessing information_schema on 10.5  (Axel Rau <Axel.Rau@Chaos1.DE>)
Responses Re: Getting fancy errors when accessing information_schema on 10.5  (Axel Rau <Axel.Rau@Chaos1.DE>)
Re: Getting fancy errors when accessing information_schema on 10.5  (Laurenz Albe <laurenz.albe@cybertec.at>)
List pgsql-admin
Axel Rau <Axel.Rau@Chaos1.DE> writes:
>> Am 30.10.2018 um 08:42 schrieb Laurenz Albe <laurenz.albe@cybertec.at>:
>> Could you run EXPLAIN on the query and tell us the execution plan?

> EXPLAIN  SELECT sequence_name AS relname, sequence_schema AS schemaname
> FROM information_schema.sequences
> WHERE sequence_schema NOT LIKE 'pg\_%' AND sequence_schema != 'information_schema';
> ...
>                      ->  Seq Scan on pg_class c  (cost=0.00..28.56 rows=22 width=72)
>                            Filter: ((pg_has_role(relowner, 'USAGE'::text) OR has_sequence_privilege(oid, 'SELECT,
UPDATE,USAGE'::text)) AND (relkind = 'S'::"char")) 

Well, there's the problem: for some reason the planner is deciding to
execute the privilege test before the relkind check.

>> Perhaps this is some fancy kind of catalog corruption…

> Maybe, as this does not happen with another instance.

It doesn't happen for me either.  Looking at the planner code, it seems
like the relkind check should happen first because it'd be cheaper than
the OR condition.  Have you perhaps messed with the cost attributed to
pg_has_role(), has_sequence_privilege(), or chareq()?  You could
investigate with, eg,

select oid::regprocedure, procost from pg_proc
  where proname = 'has_sequence_privilege';

            regards, tom lane


pgsql-admin by date:

Previous
From: Subodh Kumar
Date:
Subject: creating table without columns
Next
From: Axel Rau
Date:
Subject: Re: Getting fancy errors when accessing information_schema on 10.5