Re: [GENERAL] Shared WAL archive between master and standby: WALs notalways identical

On 02/27/2017 04:40 PM, Sasa Vilic wrote:

Hallo,

I am trying to setup shared WAL archive between master and standby.
Standby is synchronously streaming from master and both servers run with
archive_mode = always. The ideas is that when promoting standby to
master we would not missed WALs.

I seem to be missing the point of duplicating your effort.

You are doing this, correct?:

Master WAL --> WAL archive <--
                              |
Master stream --> Standby --> |

I can't see how the Standby contributes anything to the archive that it does not already have from the Master?

My problem is that sometimes WAL uploaded from master and from slave are
not 100% identical. In most cases they are but occasionally they are
not. I have written small script that ensures that upload is free of
race condition and I log md5 sum of each WAL. Aren't WALs from master
and standby supposed to be identical? After all, standby is just
consuming WAL that it is receiving from master ...

Or do you have any better suggestion on how to achieve continuous
incremental backup?

Thanks in advance

--
Adrian Klaver
adrian.klaver@aklaver.com