Horton

Re: Defer selection of asynchronous subplans until the executor initialization stage

Etsuro Fujita <etsuro.fujita@gmail.com>

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From: Etsuro Fujita <etsuro.fujita@gmail.com>
To: Zhihong Yu <zyu@yugabyte.com>
Cc: Alexander Pyhalov <a.pyhalov@postgrespro.ru>, "Andrey V. Lepikhov" <a.lepikhov@postgrespro.ru>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-06-02T12:08:28Z
Lists: pgsql-hackers

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On Wed, Apr 6, 2022 at 3:58 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> I have committed the patch after modifying it as such.

The patch calls trivial_subqueryscan() during create_append_plan() to
determine the triviality of a SubqueryScan that is a child of an
Append node.  Unlike when calling it from
set_subqueryscan_references(), this is done before some
post-processing such as set_plan_references() on the subquery.  The
reason why this is safe wouldn't be that obvious, so I added to
trivial_subqueryscan() comments explaining this.  Attached is a patch
for that.

Best regards,
Etsuro Fujita

Commits

  1. Improve comments for trivial_subqueryscan().

  2. Disable asynchronous execution if using gating Result nodes.

  3. Allow asynchronous execution in more cases.

  4. Doc: Further update documentation for asynchronous execution.

  5. Fix rescanning of async-aware Append nodes.

  6. Doc: Update documentation for asynchronous execution.

  7. Fix EXPLAIN ANALYZE for async-capable nodes.

  8. Minor code cleanup in asynchronous execution support.

  9. Adjust input value to WaitEventSetWait() in ExecAppendAsyncEventWait().

  10. Add support for asynchronous execution.