Re: [bug?] Missed parallel safety checks, and wrong parallel safety

On Tue, Jul 27, 2021 at 11:28 AM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Tue, Jul 27, 2021 at 10:44 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Mon, Jul 26, 2021 at 8:33 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > Consider below ways to allow the user to specify the parallel-safety option:
> >
> > (a)
> > CREATE TABLE table_name (...) PARALLEL DML { UNSAFE | RESTRICTED | SAFE } ...
> > ALTER TABLE table_name PARALLEL DML { UNSAFE | RESTRICTED | SAFE } ..
> >
> > OR
> >
> > (b)
> > CREATE TABLE table_name (...) WITH (parallel_dml_enabled = true)
> > ALTER TABLE table_name (...) WITH (parallel_dml_enabled = true)
> >
> > The point was what should we do if the user specifies the option for a
> > non-partitioned table. Do we just ignore it or give an error that this
> > is not a valid syntax/option when used with non-partitioned tables? I
> > find it slightly odd that this option works for partitioned tables but
> > gives an error for non-partitioned tables but maybe we can document
> > it.
>
> IMHO, for a non-partitioned table, we should be default allow the
> parallel safely checking so that users don't have to set it for
> individual tables, OTOH, I don't think that there is any point in
> blocking the syntax for the non-partitioned table, So I think for the
> non-partitioned table if the user hasn't set it we should do automatic
> safety checking and if the user has defined the safety externally then
> we should respect that. And for the partitioned table, we will never
> do the automatic safety checking and we should always respect what the
> user has set.
>

This is exactly what I am saying. BTW, do you have any preference for
the syntax among (a) or (b)?

--
With Regards,
Amit Kapila.