Re: finding changed blocks using WAL scanning

On Mon, Apr 22, 2019 at 12:15:32PM -0400, Robert Haas wrote:
> On Mon, Apr 22, 2019 at 11:48 AM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > My point is that you would normally only remove the modblock file when 4
> > is removed because this modblock files is useful for incremental backups
> > from base backups that happened between 1 and 4.
>
> That's an interesting point. On the other hand, I think it would be
> typical to want the master to retain .modblock files for much longer
> than it retains WAL segments, and in my design, the WAL archive
> wouldn't see those files at all; they'd be stored on the master. I
> was actually thinking that they should possibly be stored in a
> separate directory to avoid confusion.

I assumed the modblock files would be stored in the WAL archive so some
external tools could generate incremental backups using just the WAL
files. I assumed they would also be sent to standby servers so
incremental backups could be done on standby servers too.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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