Re: Protocol 2 and query parameters support

On Sun, Apr 23, 2017 at 10:33 PM, Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp> wrote:

> > Andres Freund <andres(at)anarazel(dot)de> writes:
> >> On 2017-04-23 12:08:51 -0700, Konstantin Izmailov wrote:
> >>> Some systems (Presto) are still using protocol 2, and I need to
> understand
> >>> the scope of changes in the middleware to support protocol 2.
> >
> >> Could you provide a reference about presto using v2 protocol? A quick
> >> search didn't turn anything up. Presto seems a bit too new to rely on
> >> v2, given how long ago v3 has been introduced.
> >
> > There's been moderately serious discussion about dropping v2 support
> > altogether, so I sure hope there isn't anything in the wild that still
> > depends on it.
> >
> > Also, moving from v2 to v3 per se just isn't very hard, if you aren't
> > worried about making use of new-in-v3 protocol features. I wonder
> whether
> > Konstantin is confusing v2 vs v3 with use of simple vs. extended query
> > protocol within v3.
>
> It seems Presto uses v3 protocol only when ODBC driver is used. If
> JDBC is used, it is required to set "protocolVersion=2" property of
> JDBC driver, which means v2 protocol is used I think.
>
> https://github.com/treasure-data/prestogres#limitation
>
>
As Tom mentioned, it sounds like the issue is that Presto expects to only
use simple query, not extended query (no server-side prepared statements).
The JDBC driver supports setting the prepare threshold to 0 to disable
using server-side prepares.

https://jdbc.postgresql.org/documentation/publicapi/org/postgresql/PGStatement.html#setPrepareThreshold-int-

"If threshold is zero, server-side prepare will not be used."

> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
>
> --
> Sent via pgsql-general mailing list (pgsql-general(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general
>