On Sun, Apr 23, 2017 at 10:33 PM, Tatsuo Ishii <ishii@xxxxxxxxxxxx> wrote:
> Andres Freund <andres@xxxxxxxxxxx> 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.
"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
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