Subject: Re: Allow escape in application_name (was: [postgres_fdw] add local
 pid to fallback_application_name)
To: "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com>
Cc: "'pgsql-hackers@lists.postgresql.org'"
 <pgsql-hackers@lists.postgresql.org>, 'Tom Lane' <tgl@sss.pgh.pa.us>
References: 
 <TYCPR01MB5870D1E8B949DAF6D3B84E02F5F29@TYCPR01MB5870.jpnprd01.prod.outlook.com>
 <ed1c8ef2-16ac-4e56-d302-b1ff430baeec@oss.nttdata.com>
 <TYAPR01MB58661635D3884E3B863ED01CF5C79@TYAPR01MB5866.jpnprd01.prod.outlook.com>
 <TYAPR01MB5866EF9624D2DFA8A74E5E94F5CC9@TYAPR01MB5866.jpnprd01.prod.outlook.com>
From: Fujii Masao <masao.fujii@oss.nttdata.com>
Message-ID: <8f985ba0-2e79-ab67-4fa4-d35024188047@oss.nttdata.com>
Date: Wed, 1 Sep 2021 14:13:13 +0900
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0)
 Gecko/20100101 Thunderbird/78.13.0
MIME-Version: 1.0
In-Reply-To: 
 <TYAPR01MB5866EF9624D2DFA8A74E5E94F5CC9@TYAPR01MB5866.jpnprd01.prod.outlook.com>
Content-Type: text/plain; charset=iso-2022-jp; format=flowed; delsp=yes
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/8f985ba0-2e79-ab67-4fa4-d35024188047%40oss.nttdata.com>
Precedence: bulk


On 2021/08/31 16:11, kuroda.hayato@fujitsu.com wrote:
> Dear Fujii-san,
> 
> I attached new version, that almost all codes
> moved from libpq to postgres_fdw.

Thanks for updating the patch!

Can we split the patch into two as follows? If so, we can review
and commit them one by one.

#1. Add application_name GUC into postgres_fdw
#2. Allow to specify special escape characters in application_name that postgres_fdw uses.


> 
> Now we can accept four types of escapes.
> All escapes will be rewritten to connection souce's information:
> 
> * application_name,
> * user name,
> * database name, and
> * backend's pid.

+1


> 
> These are cannot be set by log_line_prefix, so I think it is useful.
> 
> 
> We can use escape sequences in two ways:
> * Sets postgres_fdw.application_name GUC paramter, or
> * Sets application_name option in CREATE SERVER command.

OK.


> 
> Which version do you like?

For now I've not found real use case that implementing the feature
in libpq would introduce. So IMO postgres_fdw version is better.

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION