Re: 9.5 new setting "cluster name" and logging

On Sat, Feb 20, 2016 at 12:52 AM, Evan Rempel <erempel@uvic.ca> wrote:
> On 02/19/2016 05:56 AM, Fujii Masao wrote:
>>
>> On Fri, Feb 19, 2016 at 7:05 AM, Evan Rempel <erempel@uvic.ca> wrote:
>>>
>>> On 02/18/2016 01:53 PM, Tom Lane wrote:
>>>>
>>>> Bruce Momjian <bruce@momjian.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,
>>
>
> I would think that in the case of using a csvlog that you would configure
> the log_line_prefix to not include the escape sequence of the cluster_name.
> The administrator would tune all of the logging components to work together,
> or am I missing something here?

log_line_prefix is only for stderr and syslog, not for csvlog.
It cannot control what to output in csvlog, for now.

Regards,

--
Fujii Masao