Date: Wed, 23 Jun 2021 13:03:52 +0200
From: Boris Kolpackov <boris@codesynthesis.com>
To: Alvaro Herrera <alvaro.herrera@2ndquadrant.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Pipeline mode and PQpipelineSync()
Message-ID: <boris.20210623125826@codesynthesis.com>
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Alvaro Herrera <alvaro.herrera@2ndquadrant.com> writes:

> On 2021-Jun-22, Alvaro Herrera wrote:
> 
> > > So I think it would be useful to clarify the server behavior and
> > > specify it in the documentation.
> > 
> > I'll see about improving the docs on these points.
> 
> So I started to modify the second paragraph to indicate that the client
> would send data on PQflush/buffer full/PQpipelineSync, only to realize
> that the first paragraph already explains this.  So I'm not sure if any
> changes are needed.
> 
> Maybe your complaint is only based on disagreement about what does libpq
> do regarding queueing commands; and as far as I can tell in quick
> experimentation with libpq, it works as the docs state already.

I think one change that is definitely needed is to make it clear that
the PQpipelineSync() call is not optional.

I would also add a note saying that while the server starts processing
the pipeline immediately, it may buffer the results and the only way
to flush them out is to call PQpipelineSync().