Re: [COMMITTERS] pgsql: Keep track of transaction commit timestamps

On 19/12/14 13:17, Michael Paquier wrote:
> On Fri, Dec 19, 2014 at 6:30 PM, Petr Jelinek <petr@2ndquadrant.com> wrote:
>> On 10/12/14 16:03, Petr Jelinek wrote:
>>>
>>> On 10/12/14 04:26, Michael Paquier wrote:
>>>>
>>>> On Thu, Dec 4, 2014 at 9:26 PM, Heikki Linnakangas
>>>> <hlinnakangas@vmware.com> wrote:
>>>>>
>>>>> Yeah, it was raised. I don't think it was really addressed. There was
>>>>> lengthy discussion on whether to include LSN, node id, and/or some other
>>>>> information, but there was no discussion on:
>>>>>
>>>>> * What is a node ID?
>>>>> * How is it used?
>>>>> * Who assigns it?
>>>>>
>>>>> etc.
>>>>>
>>>>> None of those things are explained in the documentation nor code
>>>>> comments.
>>>>>
>>>
>>>>
>>>> Could it be possible to get a refresh on that before it bitrots too
>>>> much or we'll simply forget about it? In the current state, there is
>>>> no documentation able to explain what is the point of the nodeid
>>>> stuff, how to use it and what use cases it is aimed at. The API in
>>>> committs.c should as well be part of it. If that's not done, I think
>>>> that it would be fair to remove this portion and simply WAL-log the
>>>> commit timestamp its GUC is activated.
>>>
>>>
>>> I have this on my list so it's not being forgotten and I don't see it
>>> bitrotting unless we are changing XLog api again. I have bit busy
>>> schedule right now though, can it wait till next week? - I will post
>>> some code documentation patches then.
>> as promised I am sending code-comment patch that explains the use of commit
>> timestamps + nodeid C api for the conflict resolution, comments welcome.
> Having some documentation with this example in doc/ would be more fruitful IMO.
>

I am not sure I see point in that, the GUC and SQL interfaces are 
documented in doc/ and we usually don't put documentation for C 
interfaces there.

--  Petr Jelinek                  http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training &
Services