Re: Postgresql replication assistance - Mailing list pgsql-general

From Albe Laurenz
Subject Re: Postgresql replication assistance
Date
Msg-id D960CB61B694CF459DCFB4B0128514C2086257CE@exadv11.host.magwien.gv.at
Whole thread Raw
In response to Postgresql replication assistance  (Gustav Potgieter <gp@phunk.co.za>)
List pgsql-general
Gustav Potgieter wrote:
> Hope you can assist and that I am posting to the right forum.

Sending the question twice with the same wording does not
make it clearer...

> We currently have multiple Postgresql 9 instances running with warm
standby, and the replication work
> wonderfully.
>
> The problem is the following, we take the slave database out of
recovery and it works perfectly, but
> when we create a new database and setup streaming replication to point
to this database it is read
> only and never "starts up".
>
> "I created a test database and it did replicate across, but I could
only see it once I removed
> recovery.conf and re-started obviously not in recovery anymore, I
attached the logs at the bottom FYI"
>
> Is this even possible, to re-create a streaming database again from an
ex slave database with a base
> backup and simply re-creating recovery.conf before startup?

If I understand you correctly, there are three computers involved:
An original master, an original slave that "is taken out of recovery"
(promoted?), and a new slave that is set up using the original slave
as master.
Right?

That should work if you do it right.

You quote from a number of logs, but to me it is not clear which log
belongs to which server.

Let's say the original master is A, the original slave and new master
is B and the new slave is C.

It would be interesting to see B's log from when replication is set up
and starts working, B's log from the time it is promoted to master,
and C's log from the time when you try to set it up as B's slave.

Do you share WAL archives between the machines?
If yes, how?
How exactly did you promote B?

Yours,
Laurenz Albe


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