Horton

Re: speeding up planning with partitions

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>, Pavan Deolasee <pavan.deolasee@2ndquadrant.com>, Simon Riggs <simon@2ndquadrant.com>
Date: 2018-09-11T01:11:15Z
Lists: pgsql-hackers 
On Wed, Aug 29, 2018 at 5:06 AM, Amit Langote
<Langote_Amit_f8@lab.ntt.co.jp> wrote:
> It is more or less well known that the planner doesn't perform well with
> more than a few hundred partitions even when only a handful of partitions
> are ultimately included in the plan.  Situation has improved a bit in PG
> 11 where we replaced the older method of pruning partitions one-by-one
> using constraint exclusion with a much faster method that finds relevant
> partitions by using partitioning metadata.  However, we could only use it
> for SELECT queries, because UPDATE/DELETE are handled by a completely
> different code path, whose structure doesn't allow it to call the new
> pruning module's functionality.  Actually, not being able to use the new
> pruning is not the only problem for UPDATE/DELETE, more on which further
> below.

This was a big problem for the SQL MERGE patch. I hope that this
problem can be fixed.

-- 
Peter Geoghegan

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.