On Sat, Oct 6, 2018 at 2:59 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> The reasons why we need locks on tables not physically accessed by the
> query are (a) to ensure that we've blocked, or received sinval messages
> for, any DDL related to views or partition parent tables, in case that
> would invalidate the plan; (b) to allow firing triggers safely, in
> the case of partition parent tables. Neither of these issues apply to
> a parallel worker -- the plan is already frozen before it can ever
> start, and it isn't going to be firing any triggers either.
That last part could *easily* change in a future release. We've
already started to allow CTAS with parallel query, and there have
already been multiple people wanting to allow more. It would be a
shame if we threw up additional obstacles in the way of that...
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
