Horton

Re: speeding up planning with partitions

Jesper Pedersen <jesper.pedersen@redhat.com>

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From: Jesper Pedersen <jesper.pedersen@redhat.com>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: "Imai, Yoshikazu" <imai.yoshikazu@jp.fujitsu.com>, '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>
Date: 2019-03-12T13:23:25Z
Lists: pgsql-hackers

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Hi Amit,

On 3/12/19 4:22 AM, Amit Langote wrote:
> I wrestled with this idea a bit and concluded that we don't have to
> postpone *all* of preprocess_targetlist() processing to query_planner,
> only the part that adds row mark "junk" Vars, because only those matter
> for the problem being solved.  To recap, the problem is that delaying
> adding inheritance children (and hence their row marks if any) means we
> can't add "junk" columns needed to implement row marks, because which ones
> to add is not clear until we've seen all the children.
> 
> I propose that we delay the addition of "junk" Vars to query_planner() so
> that it doesn't stand in the way of deferring inheritance expansion to
> query_planner() too.  That means the order of reltarget expressions for
> row-marked rels will change, but I assume that's OK.  At least it will be
> consistent for both non-inherited baserels and inherited ones.
> 
> Attached updated version of the patches with the above proposal
> implemented by patch 0002.  To summarize, the patches are as follows:
> 
> 0001: make building of "other rels" a separate step that runs after
> deconstruct_jointree(), implemented by a new subroutine of query_planner
> named add_other_rels_to_query()
> 
> 0002: delay adding "junk" Vars to after add_other_rels_to_query()
> 
> 0003: delay inheritance expansion to add_other_rels_to_query()
> 
> 0004, 0005: adjust inheritance_planner() to account for the fact that
> inheritance is now expanded by query_planner(), not subquery_planner()
> 
> 0006: perform partition pruning while inheritance is being expanded,
> instead of during set_append_append_rel_size()
> 
> 0007: add a 'live_parts' field to RelOptInfo to store partition indexes
> (not RT indexes) of unpruned partitions, which speeds up looping over
> part_rels array of the partitioned parent
> 
> 0008: avoid copying PartitionBoundInfo struct for planning
> 

After applying 0004 check-world fails with the attached. CFBot agrees [1].

[1] https://travis-ci.org/postgresql-cfbot/postgresql/builds/505107884

Best regards,
  Jesper

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.