Horton

Re: why partition pruning doesn't work?

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.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>, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Pavel Stehule <pavel.stehule@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-06-13T13:47:59Z
Lists: pgsql-hackers 
On Wed, Jun 13, 2018 at 12:15 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> As for whether to change it at this point in the release cycle, I
>> guess that, to me, depends on how invasive the fix is.
>
> It seems not to be that bad: we just need a shutdown call for the
> PartitionPruneState, and then we can remember the open relation there.
> The attached is based on David's patch from yesterday.

Seems reasonable.  Really, I think we should look for a way to hang
onto the relation at the point where it's originally opened and locked
instead of reopening it here.  But that's probably more invasive than
we can really justify right at the moment, and I think this is a step
in a good direction.

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