Re: speeding up planning with partitions

On Tue, Sep 4, 2018 at 12:44 PM, Amit Langote
<Langote_Amit_f8@lab.ntt.co.jp> wrote:
> Hi Dilip,
>
> Thanks for taking a look.
>
> On 2018/09/03 20:57, Dilip Kumar wrote:
>> The idea looks interesting while going through the patch I observed
>> this comment.
>>
>> /*
>>  * inheritance_planner
>>  *   Generate Paths in the case where the result relation is an
>>  *   inheritance set.
>>  *
>>  * We have to handle this case differently from cases where a source relation
>>  * is an inheritance set. Source inheritance is expanded at the bottom of the
>>  * plan tree (see allpaths.c), but target inheritance has to be expanded at
>>  * the top.
>>
>> I think with your patch these comments needs to be change?
>
> Yes, maybe a good idea to mention that partitioned table result relations
> are not handled here.
>
> Actually, I've been wondering if this patch (0001) shouldn't get rid of
> inheritance_planner altogether and implement the new approach for *all*
> inheritance sets, not just partitioned tables, but haven't spent much time
> on that idea yet.

That will be interesting.

>
>>   if (parse->resultRelation &&
>> - rt_fetch(parse->resultRelation, parse->rtable)->inh)
>> + rt_fetch(parse->resultRelation, parse->rtable)->inh &&
>> + rt_fetch(parse->resultRelation, parse->rtable)->relkind !=
>> + RELKIND_PARTITIONED_TABLE)
>>   inheritance_planner(root);
>>   else
>>   grouping_planner(root, false, tuple_fraction);
>>
>> I think we can add some comments to explain if the target rel itself
>> is partitioned rel then why
>> we can directly go to the grouping planner.
>
> Okay, I will try to add more explanatory comments here and there in the
> next version I will post later this week.

Okay.

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