Re: assembling PGresults from multiple simultaneous queries (libpq, singlerowmode)

Yes, Andres, I meant "pipelining", just couldn't choose correct word. Thank
you for the answer(s)!

I also made changes in my own copy of libpq, and they work fine. I think
the pipelining support is needed in libpq. Btw, how can I get the patch
code? I want to compare your approach with mine. I couldn't figure out how
to get the patch from the link.

Thanks so much!

On Sun, Apr 7, 2019 at 12:21 PM Andres Freund <andres(at)anarazel(dot)de> wrote:

> Hi,
>
> On 2019-04-07 20:57:56 +0200, Pavel Stehule wrote:
> > ne 7. 4. 2019 v 20:47 odesílatel Konstantin Izmailov <pgfizm(at)gmail(dot)com>
> > napsal:
> >
> > > Hi,
> > > I'm experimenting with Postgres 10 and protocol v3. I noticed that the
> > > Postgres allows executing multiple queries simultaneously (I basically
> > > commented out a check that prevents sending another query in libpq
> while
> > > previous result(s) reading is not complete). Things appear like
> working,
> > > but I just wanted to ask if anyone else tried the same (logically
> separate
> > > results from multiple simultaneous queries)?
> > >
> > >
> > Postgres cannot to execute simultaneous queries in one session. So
> queries
> > should be executed in serial form every time.
>
> I think what Konstantin is really talking about is pipelining
> (i.e. sending multiple queries without waiting for the results
> inbetween, thereby reducing latency), and that is actually supported by
> postgres. Some drivers make fairly extensive use of it (e.g. the pgjdbc
> driver).
>
> As for libpq: No, that's currently not supported. There is a patch that
> I hope to get into v13 however: https://commitfest.postgresql.org/20/1317
>
> Greetings,
>
> Andres Freund
>