Horton

Re: [HACKERS] Runtime Partition Pruning

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>, 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: 2018-04-17T02:33:43Z
Lists: pgsql-hackers 
David Rowley wrote:

> For a while, during my review of the faster partition pruning patch I
> was asking Amit to add pfree() calls in various places for this exact
> reason, but in the end, I gave up and decided it was easier to just
> create a new memory context to call the planner function from. I've
> now forgotten the exact reason why I finally decided it was too much
> trouble.  The pruning code now works using your step logic so perhaps
> that reason no longer applies, although, on a quick scan of the
> pruning code now, it seems to require that get_matching_partitions
> performs a deep pfree of each PruneStepResult. However, there is still
> partkey_datum_from_expr which performs ExecInitExpr, although perhaps
> that can just be done once, and the result stashed in the
> PartitionPruneContext.

I think trying to replace a well-placed MemoryContextReset (or Delete)
with a bunch of individual pfrees is pointless.

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