Horton

Re: [HACKERS] Runtime Partition Pruning

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

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Beena Emerson <memissemerson@gmail.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, amul sul <sulamul@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2017-12-21T23:53:33Z
Lists: pgsql-hackers 
On 22 December 2017 at 12:45, Robert Haas <robertmhaas@gmail.com> wrote:
> PREPARE q3 (int, int) AS SELECT * FROM unpartitioned_table WHERE
> partkey BETWEEN $1 AND $2;
>
> ...that has to decide whether to use an index.  And to do that it has
> to estimate what fraction of the table will match the BETWEEN clause.
> That may be an uninformed guess, but it guesses something.  We
> probably want to do something here that makes the guess for a
> partitioned_table similar to the guess for an unpartitioned_table.

Are you considering some sort of clauselist_selectivity() estimate on
the given parameters and comparing that to the same selectivities that
were determined for the previous custom plans?

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

Commits

  1. Initialize ExprStates once in run-time partition pruning

  2. Add bms_prev_member function

  3. Support partition pruning at execution time

  4. Document partprune.c a little better

  5. Fix crash in pg_replication_slot_advance

  6. Add parallel-aware hash joins.

  7. Fix typo.

  8. Allow --with-bonjour to work with non-macOS implementations of Bonjour.

  9. Mention need for --no-inc-recursive in rsync command