Horton

Re: why partition pruning doesn't work?

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

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.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: 2018-06-13T04:55:25Z
Lists: pgsql-hackers 
On 13 June 2018 at 16:15, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 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.
>
> I'm still a bit annoyed at the fmgr_info_copy calls in this.  It'd be
> better to use the FmgrInfos in the relcache when applicable.  However,
> mixing those with the cross-type ones would seem to require that we change
> the API for get_matching_hash_bounds et al from taking "FmgrInfo *" to
> taking "FmgrInfo **", which looks rather invasive.

I've looked over this and it seems better than mine. Especially so
that you've done things so that the FmgrInfo is copied into a memory
context that's not about to get reset.

One small thing is that I'd move the:

context.partrel = NULL;

to under:

/* These are not valid when being called from the planner */

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

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