Horton

Re: Partition-wise join for join between (declaratively) partitioned tables

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>, Thomas Munro <thomas.munro@enterprisedb.com>, Rafia Sabih <rafia.sabih@enterprisedb.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-10-05T13:48:47Z
Lists: pgsql-hackers 
Robert Haas wrote:

> Regarding nomenclature and my previous griping about wisdom, I was
> wondering about just calling this a "partition join" like you have in
> the regression test.  So the GUC would be enable_partition_join, you'd
> have generate_partition_join_paths(), etc.  Basically just delete
> "wise" throughout.

If I understand correctly, what's being used here is the "-wise" suffix,
unrelated to wisdom, which Merriam Webster lists as "adverb combining
form" here https://www.merriam-webster.com/dictionary/wise (though you
have to scroll down a lot), which is defined as

1 a :in the manner of  * crabwise * fanwise
  b :in the position or direction of  * slantwise * clockwise
2 :with regard to :in respect of * dollarwise

According to that, the right way to write this is "partitionwise join"
(no dash), which means "join in respect of partitions", "join with
regard to partitions".

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Add test for partitionwise join involving default partition.

  2. Rewrite the code that applies scan/join targets to paths.

  3. Fix code related to partitioning schemes for dropped columns.

  4. Copy information from the relcache instead of pointing to it.

  5. Basic partition-wise join functionality.

  6. Associate partitioning information with each RelOptInfo.

  7. Expand partitioned table RTEs level by level, without flattening.

  8. Set partitioned_rels appropriately when UNION ALL is used.

  9. Remove dedicated B-tree root-split record types.

  10. Assorted preparatory refactoring for partition-wise join.

  11. Teach adjust_appendrel_attrs(_multilevel) to do multiple translations.

  12. Avoid unnecessary single-child Append nodes.

  13. Revisit handling of UNION ALL subqueries with non-Var output columns.