Re: Add last commit LSN to pg_last_committed_xact() - Mailing list pgsql-hackers

From James Coleman
Subject Re: Add last commit LSN to pg_last_committed_xact()
Date
Msg-id CAAaqYe_Phonup0tivOG4dHuTVcKOPbqaV7dhLwNqiqDVfsU1LQ@mail.gmail.com
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In response to Re: Add last commit LSN to pg_last_committed_xact()  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
List pgsql-hackers
On Tue, Jan 18, 2022 at 1:52 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2022-Jan-18, James Coleman wrote:
>
> > Reading the code it seems the only usage (besides
> > the boolean activation status also stored there) is in
> > TransactionIdGetCommitTsData, and the only consumers of that in core
> > appear to be the SQL callable functions to get the latest commit info.
> > It is in commit_ts.h though, so I'm guessing someone is using this
> > externally (and maybe that's why the feature has the shape it does).
>
> Logical replication is the intended consumer of that info, for the
> purposes of conflict handling.  I suppose pglogical uses it, but I don't
> know that code myself.
>
> [ ... greps ... ]
>
> Yeah, that function is called from pglogical.

That's interesting, because my use case for the lsn is also logical
replication (monitoring).

James Coleman



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