Re: Streaming rep - why log shipping is necessary?

On Thu, Feb 25, 2010 at 10:08 AM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> the standby needs to
> fall back to the archive if it falls behind so that the WAL files it
> needs have already been recycled in the master.

Oh, so the master does not have to keep track of the state of the
standbys. That`s a nice design.

> If you're adventurous enough, it's actually possible to set an
> archive_command that checks the status of the standby and returns
> failure as long as the standby still needs the given WAL segment. That
> way the primary doesn't recycle segments that are still needed by the
> standby, and you can get away without restore_command in the standby.

That would be a nice addition to pg_standby, like
pg_standby --check-streaming-standby postgres:qwerty(at)10(dot)0(dot)0(dot)1
--check-streaming-standby postgres:qwerty(at)10(dot)0(dot)0(dot)2:5433

Greetings
Marcin Mańk