Horton

Re: generic plans and "initial" pruning

Amit Langote <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, David Rowley <dgrowleyml@gmail.com>, Jacob Champion <jchampion@timescale.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2023-03-27T14:00:38Z
Lists: pgsql-hackers

Attachments

> > On Tue, Mar 14, 2023 at 7:07 PM Amit Langote <amitlangote09@gmail.com> wrote:
> > > * I decided to initialize QueryDesc.planstate even in the cases where
> > > ExecInitNode() traversal is aborted in the middle on detecting
> > > CachedPlan invalidation such that it points to a partially initialized
> > > PlanState tree.  My earlier thinking that each PlanState node need not
> > > be visited for resource cleanup in such cases was naive after all.  To
> > > that end, I've fixed the ExecEndNode() subroutines of all Plan node
> > > types to account for potentially uninitialized fields.  There are a
> > > couple of cases where I'm a bit doubtful though.  In
> > > ExecEndCustomScan(), there's no indication in CustomScanState whether
> > > it's OK to call EndCustomScan() when BeginCustomScan() may not have
> > > been called.  For ForeignScanState, I've assumed that
> > > ForeignScanState.fdw_state being set can be used as a marker that
> > > BeginForeignScan would have been called, though maybe that's not a
> > > solid assumption.

It seems I hadn't noted in the ExecEndNode()'s comment that all node
types' recursive subroutines need to  handle the change made by this
patch that the corresponding ExecInitNode() subroutine may now return
early without having initialized all state struct fields.

Also noted in the documentation for CustomScan and ForeignScan that
the Begin*Scan callback may not have been called at all, so the
End*Scan should handle that gracefully.

-- 
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.