Subject: Re: A patch for get origin from commit_ts.
To: michael@paquier.xyz, Simon Riggs <simon@2ndquadrant.com>
Cc: Madan Kumar <madankumar1993@gmail.com>,
 "movead.li@highgo.ca" <movead.li@highgo.ca>,
 pgsql-hackers <pgsql-hackers@lists.postgresql.org>,
 Craig Ringer <craig@2ndquadrant.com>,
 =?UTF-8?Q?=c3=81lvaro_Herrera?= <alvherre@2ndquadrant.com>,
 Andres Freund <andres@anarazel.de>, soumyadeep2007@gmail.com
References: <2020051116430836450630@highgo.ca>
 <20200512014537.GF88791@paquier.xyz> <2020051316291300911447@highgo.ca>
 <CAMtsaPEm47-mD5br8O8fVsZ0PnowtNij4O3UNsuG6Zb7dSCAaQ@mail.gmail.com>
 <CANP8+jJu-bta+4KBRDf2XKsHybDBY1Ew_zvcuoTdhES+ZWLGcQ@mail.gmail.com>
 <20200702015852.GE10408@paquier.xyz>
From: Petr Jelinek <petr@2ndquadrant.com>
Message-ID: <4ee522fa-b549-4a8d-9d9e-cb27be774627@2ndquadrant.com>
Date: Thu, 2 Jul 2020 10:12:02 +0200
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On 02/07/2020 03:58, michael@paquier.xyz wrote:
> On Tue, Jun 30, 2020 at 01:58:17PM +0100, Simon Riggs wrote:
>> On Tue, 30 Jun 2020 at 02:17, Madan Kumar <madankumar1993@gmail.com> wrote:
>>> It may be better to have one single function returning both
>>> timestamp and origin for a given transaction ID.
>>
>> No need to change existing APIs.
> 
> Adding a new function able to return both fields at the same time does
> not imply that we'd remove the original one, it just implies that we
> would be able to retrieve both fields with a single call of
> TransactionIdGetCommitTsData(), saving from an extra CommitTsSLRULock
> taken, etc.  That's actually what pglogical does with
> its pglogical_xact_commit_timestamp_origin() in
> pglogical_functions.c.  So adding one function able to return one
> tuple with the two fields, without removing the existing
> pg_xact_commit_timestamp() makes the most sense, no?


Agreed, sounds reasonable.

I also (I suspect like Álvaro) parsed your original message as wanting 
to remove origin from the record completely.

-- 
Petr Jelinek
2ndQuadrant - PostgreSQL Solutions for the Enterprise
https://www.2ndQuadrant.com/