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: 2022-04-06T06:58:29Z
Lists: pgsql-hackers 
On Mon, Apr 4, 2022 at 1:06 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> On Sun, Apr 3, 2022 at 11:38 PM Zhihong Yu <zyu@yugabyte.com> wrote:
> > +   WRITE_ENUM_FIELD(status, SubqueryScanStatus);
> >
> > Looks like the new field can be named subquerystatus - this way its purpose is clearer.
>
> I agree that “status” is too general.  “subquerystatus” might be good,
> but I’d like to propose “scanstatus” instead, because I think this
> would be consistent with the naming of the RowMarkType-enum member
> “markType” in PlanRowMark defined in the same file.
>
> > + * mark_async_capable_plan
> > + *     Check whether a given Path node is async-capable, and if so, mark the
> > + *     Plan node created from it as such.
> >
> > Please add comment explaining what the return value means.
>
> Ok, how about something like this?
>
> “Check whether a given Path node is async-capable, and if so, mark the
> Plan node created from it as such and return true; otherwise, return
> false.”

I have committed the patch after modifying it as such.  (I think we
can improve these later, if necessary.)

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.