Re: table_open/table_close with different lock mode

On Fri, Jul 21, 2023 at 02:05:56PM +0800, Junwang Zhao wrote:
> I noticed there are some places calling table_open with
> RowExclusiveLock but table_close with NoLock, like in function
> toast_save_datum.
>
> Can anybody explain the underlying logic, thanks in advance.

This rings a bell.  This is a wanted behavior, see commit f99870d and
its related thread:
https://postgr.es/m/17268-d2fb426e0895abd4@postgresql.org

The tests added by this commit in src/test/isolation/ will show the
difference in terms of the way the toast values get handled with and
without the change.
--
Michael