Re: How to choose new master from slaves.?

On 2022-08-04 07:43:28 +0000, Sacheen Birhade wrote:
> I have a very basic question about streaming replication feature of Postgres.
> Let’s assume I have servers A, B, C, D, & E with postgres installed with
> streaming replication as follow:
> A à B ( sync replication )
> A à C ( async replication )
> A à D ( async replication )
> A à E ( async replication )
> A is master & rest are slaves.
>
> Now my question is:
> Assume replication link between A & B may/may not stable.

Using sync replication on an unstable link is probably not a good idea.
Every time the link goes down, A freezes. Is this what you want?

> If A goes down, how will I choose my new master from slaves? What are
> criteria to choose new master?

I would prefer B over the others because it is in sync with A, so you
don't lose data. All the other ones might.

Otherwise: For the same reason I would prefer B, I would prefer the one
with the most up-to-date data. But there might be other considerations,
e.g. the network connections (bandwidth and delays) between the
surviving members and the clients.

hp

--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp(at)hjp(dot)at | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"