On Fri, Feb 24, 2017 at 11:30 AM, Dilip Kumar <dilipbal...@gmail.com> wrote:
> On Fri, Feb 24, 2017 at 10:06 AM, Amit Kapila <amit.kapil...@gmail.com> wrote:
>> We have a below check in standard_planner() (!IsParallelWorker())
>> which should prohibit generating parallel plan inside worker, if that
>> is what you are seeing, then we might need a similar check at other
>> places.
>>
>> if ((cursorOptions & CURSOR_OPT_PARALLEL_OK) != 0 &&
>> IsUnderPostmaster &&
>> dynamic_shared_memory_type != DSM_IMPL_NONE &&
>> parse->commandType == CMD_SELECT &&
>> !parse->hasModifyingCTE &&
>> max_parallel_workers_per_gather > 0 &&
>> !IsParallelWorker() &&
>> !IsolationIsSerializable())
>> {
>> /* all the cheap tests pass, so scan the query tree */
>> glob->maxParallelHazard = max_parallel_hazard(parse);
>> glob->parallelModeOK = (glob->maxParallelHazard != PROPARALLEL_UNSAFE);
>> }
>
> Ok, I see. But, the problem with PL functions is that plan might have
> already generated in previous execution of the function and during
> that time outer query might not be running in parallel.
>Sure, but that should only happen if the function is *not* declared as parallel safe (aka in parallel safe functions, we should not generate parallel plans). > So I think we > may need some check during execution time as well? > Right, I also think we need some mechanism where if the user has not marked the parallel safe functions appropriately, then such executions should result in error. For example, if parallel-safe function calls a parallel-unsafe function which contains either write statement or statement that could generate a parallel plan, then we should not allow execution of such queries. We already have safeguard checks at most places like write statements (see heap_update), however, I think we need a similar check in ExecGather. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
