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Re: [HACKERS] path toward faster partition pruning

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

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Amit Langote <amitlangote09@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-04-11T08:59:48Z
Lists: pgsql-hackers

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On 11 April 2018 at 18:04, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote:
> Updated patch attached.

Thanks for the updated patch.

The only thing I'm not sure about is the chances you've made to the
COALESCE function.

+CREATE OR REPLACE FUNCTION pp_hashint4_noop(int4, int8) RETURNS int8 AS
+$$SELECT coalesce($1, $2)::int8$$ LANGUAGE sql IMMUTABLE;
+CREATE OPERATOR CLASS pp_test_int4_ops FOR TYPE int4 USING HASH AS
+OPERATOR 1 = , FUNCTION 2 pp_hashint4_noop(int4, int8);
+CREATE OR REPLACE FUNCTION pp_hashtext_length(text, int8) RETURNS int8 AS
+$$SELECT length(coalesce($1, ''))::int8$$ LANGUAGE sql IMMUTABLE;

Why does one default to the seed and the other to an empty string?
Shouldn't they both do the same thing? If you were to copy the
hash_part.sql you'd just coalesce($1, 0) and coalesce($1, ''), any
special reason not to do that?

Also just wondering if it's worth adding some verification that we've
actually eliminated the correct partitions by backing the tests up
with a call to satisfies_hash_partition.

I've attached a delta patch that applies to your v2 which does this.
Do you think it's worth doing?

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

Commits

  1. Fix assorted partition pruning bugs

  2. Make gen_partprune_steps static

  3. Remove useless 'default' clause

  4. Reorganize partitioning code

  5. Use custom hash opclass for hash partition pruning

  6. Blindly attempt to fix sepgsql tests broken due to 9fdb675fc5.

  7. Attempt to fix endianess issues in new hash partition test.

  8. Faster partition pruning

  9. For partitionwise join, match on partcollation, not parttypcoll.

  10. Revise API for partition bound search functions.

  11. Revise API for partition_rbound_cmp/partition_rbound_datum_cmp.

  12. Fix possible crash in partition-wise join.

  13. Refactor code for partition bound searching

  14. New C function: bms_add_range

  15. Add extensive tests for partition pruning.

  16. Add null test to partition constraint for default range partitions.

  17. Remove BufFile's isTemp flag.

  18. Make OWNER TO subcommand mention consistent

  19. Fix index matching for operators with mixed collatable/noncollatable inputs.