Horton

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

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Rafia Sabih <rafia.sabih@enterprisedb.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-04-26T16:43:27Z
Lists: pgsql-hackers 
On Wed, Apr 26, 2017 at 12:41 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> So this is about a cross-type join,
>> not multiple types within a single partitioning hierarchy, as you
>> might also gather from the subject line of this thread.
>
> OK, but I still don't understand why any type conversion is needed
> in such a case.  The existing join estimators don't try to do that,
> for the good and sufficient reasons you and I have already mentioned.
> They just apply the given cross-type join operator, and whatever
> cross-type selectivity estimator might be associated with it, and
> possibly other cross-type operators obtained from the same btree
> opfamily.
>
> The minute you get into trying to do any type conversion that is not
> mandated by the semantics of the query as written, you're going to
> have problems.

There is no daylight whatsoever between us on this issue.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Basic partition-wise join functionality.

  2. Assorted preparatory refactoring for partition-wise join.

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

  4. Stamp 10beta2.

  5. Eat XIDs more efficiently in recovery TAP test.

  6. Abstract logic to allow for multiple kinds of child rels.

  7. Implement SortSupport for macaddr data type

  8. Attempt to stabilize grouping sets regression test plans.

  9. Teach xlogreader to follow timeline switches

  10. Don't scan partitioned tables.

  11. Fix grammar.

  12. postgres_fdw: Push down FULL JOINs with restriction clauses.

  13. Some preliminary refactoring towards partitionwise join.

  14. contrib/amcheck needs RecentGlobalXmin to be PGDLLIMPORT'ified.

  15. Print test parameters like "foo: 123", and results like "foo = 123".