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: "Imai, Yoshikazu" <imai.yoshikazu@jp.fujitsu.com>, 'Amit Langote' <Langote_Amit_f8@lab.ntt.co.jp>, 'Amit Langote' <amitlangote09@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <david.rowley@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-03-20T14:25:05Z
Lists: pgsql-hackers 
Hi,

On 3/19/19 11:15 PM, Imai, Yoshikazu wrote:
> Here the details.
> 
> [creating partitioned tables (with 1024 partitions)]
> drop table if exists rt;
> create table rt (a int, b int, c int) partition by range (a);
> \o /dev/null
> select 'create table rt' || x::text || ' partition of rt for values from (' ||
>   (x)::text || ') to (' || (x+1)::text || ');' from generate_series(1, 1024) x;
> \gexec
> \o
> 
> [select1024.sql]
> \set a random (1, 1024)
> select * from rt where a = :a;
> 
> [pgbench]
> pgbench -n -f select1024.sql -T 60
> 
> 

My tests - using hash partitions - shows that the extra time is spent in 
make_partition_pruneinfo() for the relid_subplan_map variable.

   64 partitions: make_partition_pruneinfo() 2.52%
8192 partitions: make_partition_pruneinfo() 5.43%

TPS goes down ~8% between the two. The test setup is similar to the above.

Given that Tom is planning to change the List implementation [1] in 13 I 
think using the palloc0 structure is ok for 12 before trying other 
implementation options.

perf sent off-list.

[1] https://www.postgresql.org/message-id/24783.1551568303%40sss.pgh.pa.us

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.