Horton

Re: [HACKERS] Runtime Partition Pruning

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Amit Langote <amitlangote09@gmail.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Jesper Pedersen <jesper.pedersen@redhat.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, Beena Emerson <memissemerson@gmail.com>, amul sul <sulamul@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2018-04-18T15:13:01Z
Lists: pgsql-hackers 
On Mon, Apr 16, 2018 at 10:46 PM, David Rowley
<david.rowley@2ndquadrant.com> wrote:
> I did go and start working on a patch to test how possible this would
> be and came up with the attached. I've left a stray
> MemoryContextStatsDetail call in there which does indicate that
> something is not being freed. I'm just not sure what it is yet.
>
> The patch does happen to improve performance slightly, but that is
> most likely due to the caching of the ExprStates rather than the
> change of memory management. It's not really possible to do that with
> the reset unless we stored the executor's memory context in
> PartitionPruneContext and did a context switch back inside
> partkey_datum_from_expr before calling ExecInitExpr.

10% is more than a "slight" improvement, I'd say!  It's certainly got
to be worth avoiding the repeated calls to ExecInitExpr, whatever we
do about the memory contexts.

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

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