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From: Tatsuo Ishii <[email protected]>
To: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: Re: When extended query protocol ends?
Date: Thu, 01 Feb 2024 20:21:50 +0900 (JST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <CADK3HH+j2VRsjDKfre14asT2GEhTCOTgrC_+-O9CO4PVRrxe_A@mail.gmail.com>
References: <[email protected]>
	<[email protected]>
	<CADK3HH+j2VRsjDKfre14asT2GEhTCOTgrC_+-O9CO4PVRrxe_A@mail.gmail.com>

>> Hello Dave,
>>
>> > Tatsuo Ishii <[email protected]> writes:
>> >> Below is outputs from "pgproto" command coming with Pgpool-II.
>> >> (Lines starting "FE" represents a message from frontend to backend.
>> >> Lines starting "BE" represents a message from backend to frontend.)
>> >
>> >> FE=> Parse(stmt="", query="SET extra_float_digits = 3")
>> >> FE=> Bind(stmt="", portal="")
>> >> FE=> Execute(portal="")
>> >> FE=> Parse(stmt="", query="SET extra_float_digits = 3")
>> >> FE=> Bind(stmt="", portal="")
>> >> FE=> Execute(portal="")
>> >> FE=> Query (query="SET extra_float_digits = 3")
>> >> <= BE ParseComplete
>> >> <= BE BindComplete
>> >> <= BE CommandComplete(SET)
>> >> <= BE ParseComplete
>> >> <= BE BindComplete
>> >> <= BE CommandComplete(SET)
>> >> <= BE CommandComplete(SET)
>> >> <= BE ReadyForQuery(I)
>> >> FE=> Terminate
>> >
>> >> As you can see, two "SET extra_float_digits = 3" is sent in the
>> >> extended query protocol, then one "SET extra_float_digits = 3" follows
>> >> in the simple query protocol. No sync message is sent. However, I get
>> >> ReadyForQuery at the end. It seems the extended query protocol is
>> >> ended by a simple query protocol message instead of a sync message.
>> >
>> >> My question is, is this legal in terms of fronted/backend protocol?
>> >
>> > I think it's poor practice, at best.  You should end the
>> > extended-protocol query cycle before invoking simple query.
>>
>> From [1] I think the JDBC driver sends something like below if
>> autosave=always option is specified.
>>
>> "BEGIN READ ONLY" Parse/Bind/Eexecute (in the extended query protocol)
>> "SAVEPOINT PGJDBC_AUTOSAVE" (in the simple query protocol)
>>
>> It seems the SAVEPOINT is sent without finishing the extended query
>> protocol (i.e. without Sync message). Is it possible for the JDBC
>> driver to issue a Sync message before sending SAVEPOINT in simple
>> query protocol? Or you can send SAVEPOINT using the extended query
>> protocol.
>>
>> [1]
>> https://www.pgpool.net/pipermail/pgpool-general/2023-December/009051.html
>>
>>
> Hi Tatsuo,
> 
> Yes, it would be possible.
> 
> Can you create an issue on github? Issues · pgjdbc/pgjdbc (github.com)
> <https://github.com/pgjdbc/pgjdbc/issues;

Sure.

https://github.com/pgjdbc/pgjdbc/issues/3107

Best reagards,
--
Tatsuo Ishii
SRA OSS LLC
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp

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