Re: tracking commit timestamps - Mailing list pgsql-hackers

From Robert Haas
Subject Re: tracking commit timestamps
Date
Msg-id 911880D7-9168-44B7-99DC-9F90DD4B9D86@gmail.com
Whole thread Raw
In response to Re: tracking commit timestamps  (Steve Singer <steve@ssinger.info>)
Responses Re: tracking commit timestamps
List pgsql-hackers
> On Nov 5, 2014, at 7:31 PM, Steve Singer <steve@ssinger.info> wrote:
>> On 11/05/2014 05:43 PM, Andres Freund wrote:
>> On 2014-11-05 17:17:05 -0500, Steve Singer wrote:
>> Imo that's essentially a different feature. What you essentially would
>> need here is a 'commit sequence number' - but no timestamps. And
>> probably to be useful that number has to be 8 bytes in itself.
>
> I think this gets to the heart of some of the differing views people have expressed on this patch
>
> Is this patch supposed to:
>
> A)  Add commit timestamp tracking but nothing more
>
> B) Add infrastructure to store commit timestamps and provide a facility for storing additional bits of data
extensionsmight want to be associated with the commit 
>
> C).  Add commit timestamps and node identifiers to commits

Well put.

I think the authors of this patch are suffering from a certain amount of myopia.  Commit timestamps are useful, but so
arecommit LSNs, and it makes little sense to me to suppose that we should have two different systems for those
closely-relatedneeds. 

Like Andres, I think B is impractical, so let's just be honest and admit that C is what we're really doing. But let's
addLSNs so the people who want that can be happy too. 

...Robert


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