Horton

Re: generic plans and "initial" pruning

Zhihong Yu <zyu@yugabyte.com>

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From: Zhihong Yu <zyu@yugabyte.com>
To: Amit Langote <amitlangote09@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2022-05-27T20:08:39Z
Lists: pgsql-hackers 
On Fri, May 27, 2022 at 1:10 AM Amit Langote <amitlangote09@gmail.com>
wrote:

> On Mon, Apr 11, 2022 at 12:53 PM Zhihong Yu <zyu@yugabyte.com> wrote:
> > On Sun, Apr 10, 2022 at 8:05 PM Amit Langote <amitlangote09@gmail.com>
> wrote:
> >> Sending v15 that fixes that to keep the cfbot green for now.
> >
> > Hi,
> >
> > +               /* RT index of the partitione table. */
> >
> > partitione -> partitioned
>
> Thanks, fixed.
>
> Also, I broke this into patches:
>
> 0001 contains the mechanical changes of moving PartitionPruneInfo out
> of Append/MergeAppend into a list in PlannedStmt.
>
> 0002 is the main patch to "Optimize AcquireExecutorLocks() by locking
> only unpruned partitions".
>
> --
> Thanks, Amit Langote
> EDB: http://www.enterprisedb.com

Hi,
In the description:

is made available to the actual execution via
PartitionPruneResult, made available along with the PlannedStmt by the

I think the second `made available` is redundant (can be omitted).

+ * Initial pruning is performed here if needed (unless it has already been
done
+ * by ExecDoInitialPruning()), and in that case only the surviving
subplans'

I wonder if there is a typo above - I don't find ExecDoInitialPruning
either in PG codebase or in the patches (except for this in the comment).
I think it should be ExecutorDoInitialPruning.

+    * bit from it just above to prevent empty tail bits resulting in

I searched in the code base but didn't find mentioning of `empty tail bit`.
Do you mind explaining a bit about it ?

Cheers

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.