On Sun, Apr 23, 2017 at 10:33 PM, Tatsuo Ishii <ishii@sraoss.co.jp> wrote:
> Andres Freund <andres@anarazel.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.
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.