Re: Re: A prepared statement ERROR due to EMPTY_QUERY is defined as a static Instance.

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  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.
> 	
> 	
> 	
> 	
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> 

---
Naoya Anzai
Engineering Department
NEC Soft, Ltd.
E-Mail: anzai-naoya@mxu.nes.nec.co.jp
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