On Wed, Apr 02, 2025 at 10:34:58PM -0400, Corey Huinker wrote:
>>
>> > Also, why do we need the clause "WHERE s.tablename = ANY($2)"? Isn't
>> > that already implied by "JOIN unnest($1, $2) ... s.tablename =
>> > u.tablename"?
>>
>> Good question. Corey, do you recall why this was needed?
>>
>
> In my patch, that SQL statement came with the comment:
>
> + /*
> + * The results must be in the order of relations supplied in the
> + * parameters to ensure that they are in sync with a walk of the TOC.
> + *
> + * The redundant (and incomplete) filter clause on s.tablename = ANY(...)
> + * is a way to lead the query into using the index
> + * pg_class_relname_nsp_index which in turn allows the planner to avoid an
> + * expensive full scan of pg_stats.
> + *
> + * We may need to adjust this query for versions that are not so easily
> + * led.
> + */
Thanks. I included that in the latest patch set.
--
nathan
