From: | Naoya Anzai <anzai-naoya(at)mxu(dot)nes(dot)nec(dot)co(dot)jp> |
---|---|
To: | List <pgsql-jdbc(at)postgresql(dot)org> |
Cc: | Akio Iwaasa <iwaasa(at)mxs(dot)nes(dot)nec(dot)co(dot)jp> |
Subject: | Re: Re: A prepared statement ERROR due to EMPTY_QUERY is defined as a static Instance. |
Date: | 2014-03-12 02:06:29 |
Message-ID: | 116262CF971C844FB6E793F8809B51C6B7F83E@BPXM02GP.gisp.nec.co.jp |
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Lists: | pgsql-jdbc |
Hi,
Empty Query has a query response('I') without any data.
http://www.postgresql.org/docs/current/static/protocol-message-formats.html
(see EmptyQueryResponse)
In addition, PostgreSQL curtails the execution process.
(see Postgres.c:exec_execute_message)
Regards,
Naoya
> I have never seen anyone use an empty query before. I doubt it saves any bandwidth as I believe there would be a query response
>
> Dave Cramer
>
> dave.cramer(at)credativ(dot)ca
> http://www.credativ.ca
>
>
>
> On Mon, Mar 10, 2014 at 9:22 PM, David Johnston <polobo(at)yahoo(dot)com> wrote:
>
>
> Naoya Anzai wrote
>
> > Hi Dave,
> >
> > Thanks for your response.
> >
> >> Thanks for the patch! Curious how would you ever come across this ?
> >
> > This incident was reported by one of our customers.
> > So I don't know why their application executes EMPTY_QUERY frequently...
> >
> > Regards,
>
>
> The most obvious reason would be as a keep-alive query...I have no idea
> whether that is a wise decision compared to "SELECT 1;" or something that
> actually causes the server to perform work (i.e., what does the server do
> when it see the empty-string as input?).
>
> David J.
>
>
>
>
> --
> View this message in context: http://postgresql.1045698.n5.nabble.com/A-prepared-statement-ERROR-due-to-EMPTY-QUERY-is-defined-as-a-static-Instance-tp5795067p5795476.html
> Sent from the PostgreSQL - jdbc mailing list archive at Nabble.com.
>
>
>
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>
>
---
Naoya Anzai
Engineering Department
NEC Soft, Ltd.
E-Mail: anzai-naoya(at)mxu(dot)nes(dot)nec(dot)co(dot)jp
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