Date: Wed, 26 May 2021 16:59:17 -0400
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Yura Sokolov <y.sokolov@postgrespro.ru>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
Subject: Re: Add PortalDrop in exec_execute_message
Message-ID: <202105262059.dnf27qpnccuv@alvherre.pgsql>
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On 2021-May-25, Yura Sokolov wrote:

> Tom Lane писал 2021-05-21 21:23:
> > Yura Sokolov <y.sokolov@postgrespro.ru> writes:
> > > I propose to add PortalDrop at the 'if (completed)' branch of
> > > exec_execute_message.
> > 
> > This violates our wire protocol specification, which
> > specifically says
> > 
> >     If successfully created, a named portal object lasts till the end of
> >     the current transaction, unless explicitly destroyed. An unnamed
> >     portal is destroyed at the end of the transaction, or as soon as the
> >     next Bind statement specifying the unnamed portal as destination is
> >     issued. (Note that a simple Query message also destroys the unnamed
> >     portal.)
> > 
> > I'm inclined to think that your complaint would be better handled
> > by having the client send a portal-close command, if it's not
> > going to do something else immediately.
> 
> I thought about it as well. Then, if I understand correctly,
> PQsendQueryGuts and PQsendQueryInternal in pipeline mode should send
> "close portal" (CP) message after "execute" message, right?

I don't think they should do that.  The portal remains open, and the
libpq interface does that.  The portal gets closed at end of transaction
without the need for any client message.  I think if the client wanted
to close the portal ahead of time, it would need a new libpq entry point
to send the message to do that.

(I didn't add a Close Portal message to PQsendQueryInternal in pipeline
mode precisely because there is no such message in PQsendQueryGuts.
I think it would be wrong to unconditionally add a Close Portal message
to any of those places.)

-- 
Álvaro Herrera                            39°49'30"S 73°17'W