Re: speeding up planning with partitions

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.

>   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.

Thanks,
Amit