Horton

Re: speeding up planning with partitions

Amit Langote <langote_amit_f8@lab.ntt.co.jp>

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From: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
To: "Imai, Yoshikazu" <imai.yoshikazu@jp.fujitsu.com>
Cc: "'Amit Langote'" <amitlangote09@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <david.rowley@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Justin Pryzby <pryzby@telsasoft.com>, Pg Hackers <pgsql-hackers@postgresql.org>, Jesper Pedersen <jesper.pedersen@redhat.com>
Date: 2019-03-18T09:56:15Z
Lists: pgsql-hackers 
Imai-san,

On 2019/03/15 14:40, Imai, Yoshikazu wrote:
> Amit-san,
> 
> I have another little comments about v31-patches.
> 
> * We don't need is_first_child in inheritance_planner().
> 
> On Fri, Mar 8, 2019 at 9:18 AM, Amit Langote wrote:
>> On 2019/03/08 16:16, Imai, Yoshikazu wrote:
>>> I attached the diff of modification for v26-0003 patch which also
>> contains some refactoring.
>>> Please see if it is ok.
>>
>> I like the is_first_child variable which somewhat improves readability,
>> so updated the patch to use it.
> 
> I noticed that detecting first child query in inheritance_planner() is already done by "final_rtable == NIL"
> 
>         /*
>          * If this is the first non-excluded child, its post-planning rtable
>          * becomes the initial contents of final_rtable; otherwise, append
>          * just its modified subquery RTEs to final_rtable.
>          */
>         if (final_rtable == NIL)
> 
> So I think we can use that instead of using is_first_child.

That's a good suggestion.  One problem I see with that is that
final_rtable is set only once we've found the first *non-dummy* child.
So, if all the children except the last one are dummy, we'd end up never
reusing the source child objects.  Now, if final_rtable was set for the
first child irrespective of whether it turned out to be dummy or not,
which it seems OK to do, then we can implement your suggestion.

Thanks,
Amit

Commits

  1. Clean up handling of constraint_exclusion and enable_partition_pruning.

  2. Add test case exercising formerly-unreached code in inheritance_planner.

  3. Speed up planning when partitions can be pruned at plan time.

  4. Avoid crash in partitionwise join planning under GEQO.

  5. Avoid passing query tlist around separately from root->processed_tlist.

  6. Build "other rels" of appendrel baserels in a separate step.

  7. Get rid of duplicate child RTE for a partitioned table.

  8. Rearrange make_partitionedrel_pruneinfo to avoid work when we can't prune.

  9. Don't copy PartitionBoundInfo in set_relation_partition_info.

  10. Move building of child base quals out into a new function

  11. Reorganize planner code moved in b60c39759908

  12. Move inheritance expansion code into its own file

  13. Fix inherited UPDATE/DELETE with UNION ALL subqueries.

  14. Rearrange planner to save the whole PlannerInfo (subroot) for a subquery.