Horton

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

Andrei Lepikhov <a.lepikhov@postgrespro.ru>

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From: "Andrey V. Lepikhov" <a.lepikhov@postgrespro.ru>
To: Etsuro Fujita <etsuro.fujita@gmail.com>
Cc: Zhihong Yu <zyu@yugabyte.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-08-30T08:36:38Z
Lists: pgsql-hackers 
On 8/23/21 2:18 PM, Etsuro Fujita wrote:
> To just execute what was planned at execution time, I think we should
> return to the patch in [1].  The patch was created for Horiguchi-san’s
> async-execution patch, so I modified it to work with HEAD, and added a
> simplified version of your test cases.  Please find attached a patch.
> [1] https://www.postgresql.org/message-id/7fe10f95-ac6c-c81d-a9d3-227493eb9055@postgrespro.ru
I agree, this way is more safe. I tried to search for another approach, 
because here isn't general solution: for each plan node we should 
implement support of asynchronous behaviour.
But for practical use, for small set of nodes, it will work good. I 
haven't any objections for this patch.

-- 
regards,
Andrey Lepikhov
Postgres Professional

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.