Horton

Re: generic plans and "initial" pruning

Amit Langote <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2022-04-01T08:36:49Z
Lists: pgsql-hackers 
On Fri, Apr 1, 2022 at 5:20 PM David Rowley <dgrowleyml@gmail.com> wrote:
> On Fri, 1 Apr 2022 at 19:58, Amit Langote <amitlangote09@gmail.com> wrote:
> > Yes, the ExecLockRelsInfo node in the current patch, that first gets
> > added to the QueryDesc and subsequently to the EState of the query,
> > serves as that stashing place.  Not sure if you've looked at
> > ExecLockRelInfo in detail in your review of the patch so far, but it
> > carries the initial pruning result in what are called
> > PlanInitPruningOutput nodes, which are stored in a list in
> > ExecLockRelsInfo and their offsets in the list are in turn stored in
> > an adjacent array that contains an element for every plan node in the
> > tree.  If we go with a PlannedStmt.partpruneinfos list, then maybe we
> > don't need to have that array, because the Append/MergeAppend nodes
> > would be carrying those offsets by themselves.
>
> I saw it, just not in great detail. I saw that you had an array that
> was indexed by the plan node's ID.  I thought that wouldn't be so good
> with large complex plans that we often get with partitioning
> workloads.  That's why I mentioned using another index that you store
> in Append/MergeAppend that starts at 0 and increments by 1 for each
> node that has a PartitionPruneInfo made for it during create_plan.
>
> > Maybe a different name for ExecLockRelsInfo would be better?
> >
> > Also, given Tom's apparent dislike for carrying that in PlannedStmt,
> > maybe the way I have it now is fine?
>
> I think if you change how it's indexed and the other stuff then we can
> have another look.  I think the patch will be much easier to review
> once the ParitionPruneInfos are moved into PlannedStmt.

Will do, thanks.

-- 
Amit Langote
EDB: http://www.enterprisedb.com

Commits

  1. Stamp 19beta1.

  2. Revert "Don't lock partitions pruned by initial pruning"

  3. Ensure first ModifyTable rel initialized if all are pruned

  4. Fix bug in cbc127917 to handle nested Append correctly

  5. Remove unstable test suite added by 525392d57

  6. Don't lock partitions pruned by initial pruning

  7. Fix an oversight in cbc127917 to handle MERGE correctly

  8. Track unpruned relids to avoid processing pruned relations

  9. Perform runtime initial pruning outside ExecInitNode()

  10. Move PartitionPruneInfo out of plan nodes into PlannedStmt

  11. Fix setrefs.c's failure to do expression processing on prune steps.

  12. Remove obsolete executor cleanup code

  13. Revert "Move PartitionPruneInfo out of plan nodes into PlannedStmt"

  14. Move PartitioPruneInfo out of plan nodes into PlannedStmt

  15. Refactor and cleanup runtime partition prune code a little

  16. Remove some unnecessary fields from Plan trees.

  17. Remove more redundant relation locking during executor startup.

  18. Shut down Gather's children before shutting down Gather itself.