Re: 9.5 new setting "cluster name" and logging

On Fri, Feb 19, 2016 at 7:05 AM, Evan Rempel <erempel(at)uvic(dot)ca> wrote:
> On 02/18/2016 01:53 PM, Tom Lane wrote:
>>
>> Bruce Momjian <bruce(at)momjian(dot)us> writes:
>>>
>>> On Fri, Jan 29, 2016 at 10:19:45PM -0800, Evan Rempel wrote:
>>>>
>>>> Now that there is a setting to give a cluster a "name", it would be
>>>> nice to have an escape sequence in the log_line_prefix setting that
>>>> could reference the cluster_name.
>>>
>>> Uh, wouldn't the cluster name be the same on every line? Is that
>>> useful?
>>
>> I guess if you were running multiple clusters and having them all log
>> to the same syslog daemon, there might be multiple clusters' output
>> in the same log ... but we already have ways to disambiguate that case,
>> ie, syslog_ident. Likewise for Windows' event log. I don't think we
>> should consider it supported for multiple clusters to be logging into
>> the same plain files. So yeah, the use case for this seems unclear.
>>
>> regards, tom lane
>
>
> The use case is for logging to syslog.
>
> Using the syslog_ident effectively changes the "program name" to something
> other than postgres. This would break any type of SIEM system that would be
> looking for events from the program postgres. This means that if you want to
> have a cluster specific contextual identifier, it needs to be in the log
> message content, which for the purposes of postgresql means placing it into
> the log_line_prefix.
>
> It could be hard coded as part of the log_line_prefix such as
>
> log_line_prefix = 'cluster-db1:%d:%u:%h '
>
> That would work, but that means that my cluster name needs to be in the
> configuration file twice and that opens up the error scenario of not making
> them exactly the same.
>
> Allowing for the cluster_name to be referenced by an escape sequence would
> make manual and automated configuration management easier.

What if log_destination is set to csvlog? The same cluster_name is
output in every lines, and there is no way to disable it because
something like csv_line_prefix has not been supported yet?

Regards,

--
Fujii Masao