Horton

Re: Pipeline mode and PQpipelineSync()

Boris Kolpackov <boris@codesynthesis.com>

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From: Boris Kolpackov <boris@codesynthesis.com>
To: Alvaro Herrera <alvaro.herrera@2ndquadrant.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2021-06-25T07:13:53Z
Lists: pgsql-hackers 
Alvaro Herrera <alvaro.herrera@2ndquadrant.com> writes:

> IIUC the problem is that PQgetResult is indeed not prepared to deal with
> a result the first time until after the queue has been "prepared", and
> this happens on calling PQpipelineSync.  But I think the formulation in
> the attached patch works too, and the resulting code is less surprising.
> 
> I wrote a test case that works as you describe, and indeed with the
> original code it gets a NULL initially; that disappears with the
> attached patch.  Can you give it a try?

Yes, I can confirm this appears to have addressed the first issue,
thanks! The second issue [1], however, is still there even with
this patch.

[1] https://www.postgresql.org/message-id/boris.20210624103805%40codesynthesis.com

Commits

  1. libpq: Fix sending queries in pipeline aborted state

  2. Fix libpq state machine in pipeline mode

  3. Add PQsendFlushRequest to libpq