Horton

Re: why partition pruning doesn't work?

Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>

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From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David Rowley <david.rowley@2ndquadrant.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Dmitry Dolgov <9erthalion6@gmail.com>, Jeff Janes <jeff.janes@gmail.com>, Pavel Stehule <pavel.stehule@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-06-12T13:34:14Z
Lists: pgsql-hackers 
On Tue, Jun 12, 2018 at 3:54 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Not sure about a good fix for this.  It seems annoying to copy the
> rel's whole partkey data structure into query-local storage, but
> I'm not sure we have any choice.  On the bright side, there might
> be an opportunity to get rid of repeated runtime fmgr_info lookups
> in cross-type comparison situations.
>

We already do that while building part_scheme. So, if we are in
planner, it's readily available through RelOptInfo. If we need it in
the executor, we need to pass it down from RelOptInfo into one of the
execution states. I haven't looked at the patch to exactly figure out
which of these is true.

-- 
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

Commits

  1. Fix up run-time partition pruning's use of relcache's partition data.

  2. Fix access to just-closed relcache entry.

  3. Improve ExecFindInitialMatchingSubPlans's subplan renumbering logic.

  4. Improve commentary about run-time partition pruning data structures.

  5. Fix run-time partition pruning code to handle NULL values properly.

  6. Assorted cosmetic cleanup of run-time-partition-pruning code.

  7. Relocate partition pruning structs to a saner place.

  8. Improve run-time partition pruning to handle any stable expression.

  9. Support partition pruning at execution time