On Tues, August 3, 2021 3:40 PM houzj.fnst@fujitsu.com <houzj.fnst@fujitsu.com> wrote:
> Based on the discussion here, I implemented the auto-safety-check feature.
> Since most of the technical discussion happened here,I attatched the patches in
> this thread.
>
> The patches allow users to specify a parallel-safety option for both partitioned
> and non-partitioned relations, and for non-partitioned relations if users didn't
> specify, it would be computed automatically. If the user has specified
> parallel-safety option then we would consider that instead of computing the
> value by ourselves. But for partitioned table, if users didn't specify the parallel
> dml safety, it will treat is as unsafe.
>
> For non-partitioned relations, after computing the parallel-safety of relation
> during the planning, we save it in the relation cache entry and invalidate the
> cached parallel-safety for all relations in relcache for a particular database
> whenever any function's parallel-safety is changed.
>
> To make it possible for user to alter the safety to a not specified value to get the
> automatic safety check, add a new default option(temporarily named 'DEFAULT'
> in addition to safe/unsafe/restricted) about parallel dml safety.
>
> To facilitate users for providing a parallel-safety option, provide a utility
> functionr "pg_get_table_parallel_dml_safety(regclass)" that returns records of
> (objid, classid, parallel_safety) for all parallel unsafe/restricted table-related
> objects from which the table's parallel DML safety is determined.
> This will allow user to identify unsafe objects and if the required user can change
> the parallel safety of required functions and then use the parallel safety option
> for the table.
Update the commit message in patches to make it easier for others to review.
Best regards,
Houzj
