From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Issues in Replication Progress Tracking |
Date: | 2015-05-21 04:10:58 |
Message-ID: | CAA4eK1LbtWktw8ZxJcs231gRC4gukjPi42ErX=Usra5BBY7=-Q@mail.gmail.com |
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Lists: | pgsql-hackers |
On Thu, May 21, 2015 at 12:42 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> On 2015-05-20 19:27:05 +0530, Amit Kapila wrote:
>
> > 13.
> > In function replorigin_session_setup() and or
> > replorigin_session_advance(), don't we need to WAL log the
> > use of Replication state?
>
> No, the point is that the replication progress is persisted via an extra
> data block in the commit record. That's important for both performance
> and correctness, because otherwise it gets hard to tie a transaction
> made during replay with the update to the progress. Unless you use 2PC
> which isn't really an alternative.
>
Okay, but what triggered this question was the difference of those functions
as compare to when user call function pg_replication_origin_advance().
pg_replication_origin_advance() will WAL log the information during that
function call itself (via replorigin_advance()). So even if the transaction
issuing pg_replication_origin_advance() function will abort, it will still
update
the Replication State, why so?
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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