Horton

Re: speeding up planning with partitions

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, "Imai, Yoshikazu" <imai.yoshikazu@jp.fujitsu.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-02-01T14:11:35Z
Lists: pgsql-hackers 
On Fri, 1 Feb 2019 at 23:01, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
> Please rebase.

I had a short list of other things I noticed when making a partial
pass over the patch again.

I may as well send these now if there's a new version on the way:

1. I think it's okay to convert the following:

/*
* Adjust all_baserels to replace the original target relation with the
* child target relation.  Copy it before modifying though.
*/
subroot->all_baserels = bms_copy(root->all_baserels);
subroot->all_baserels = bms_del_member(subroot->all_baserels,
   root->parse->resultRelation);
subroot->all_baserels = bms_add_member(subroot->all_baserels,
   subroot->parse->resultRelation);

into:
/* Adjust all_baserels */
subroot->all_baserels = adjust_child_relids(root->all_baserels, 1, &appinfo);


2. Any reason to do:

/*
* Generate access paths for the entire join tree.
*
* For UPDATE/DELETE on an inheritance parent, join paths should be
* generated for each child result rel separately.
*/
if (root->parse->resultRelation &&
root->simple_rte_array[root->parse->resultRelation]->inh)

instead of just checking: if (root->inherited_update)

3. This seems like useless code in set_inherit_target_rel_sizes().

/*
* If parallelism is allowable for this query in general, see whether
* it's allowable for this childrel in particular.  For consistency,
* do this before calling set_rel_size() for the child.
*/
if (root->glob->parallelModeOK)
set_rel_consider_parallel(subroot, childrel, childRTE);


parallelModeOK is only ever set for SELECT.  Likely it's fine just to
replace these with:

+               /* We don't consider parallel paths for UPDATE/DELETE
statements */
+               childrel->consider_parallel = false;

or perhaps it's fine to leave it out since build_simple_rel() sets it to false.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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.