Re: [GENERAL] pgstattuple triggered checkpoint failure and database outage?

Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> Tom Lane wrote:
>> This isn't entirely trivial because it's presently expensive to
>> determine whether a table is someone else's temp table: it takes a
>> system catalog lookup. I'm not even sure that it'd be safe to have
>> the relcache do it and cache the result --- it could lead to infinite
>> recursion. (At the very least this would promote pg_namespace into
>> the set of critical relcache entries.)

> You could hard code that PG_CATALOG_NAMESPACE is not a temp namespace. I
> believe that would stop the recursion.

True.

> Would that avoid promoting
> pg_namespace to critical status, too?

Not sure. It'd still be something you have to access while loading
most relcache entries.

On balance the extra pg_class column seems like a more robust and useful
solution. I've wished for a clean way to see temp-table-ness at the SQL
level before. And we've already changed pg_class's rowtype for 8.4, so
it shouldn't pose any additional hardship from an application
compatibility standpoint.

regards, tom lane