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

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.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com