Marcin Kasperski <Marcin.Kasperski at softax.com.pl> writes:
> (just preparing to configure my first Slony setup and reading docs,
>  which seem to contain different opinions)
>
> There is machine MST on which master database runs.
> There is machine CLI on which subscriber database is to run, from
> which slonik scripts are to be executed just as most psql-s.
>
> CLI is able to reach MST 
>
> MST is *not* able to reach CLI (bah, it even can't address it at the
> moment)
>
> Will Slony-I work in such config, or not? 
> After reading http://slony.info/documentation/plainpaths.html
> I feel that it should, but a few other articles tend to require
> any-to-any communication paths.
>
> So - do master need a connection to subscriber?
>
> And if so - for what?
> (I understand that it would be needed if master had to read events
>  from subscriber, also if I were to swap master with backup, but
>  is this all?)

I assume here that you just have two databases, on two hosts, MST and
CLI.

It is necessary that the slon process managing node MST is able to
access both the MST and CLI hosts:

  - It is managing node MST, so obviously must access it;
  - It needs to be able to receive events and confirmations of events
    from node CLI.

Similarly, it is necessary that the slon process managing node CLI is
able to access both the MST and CLI hosts:

  - It is managing node CLI, so obviously must access it;
  - It needs to be able to receive events and confirmations of events
    from node MST.  With MST being the origin, it is also the case that
    this slon process will be drawing data from MST to replicate it to
    node CLI.

If CLI is able to reach MST, then you could presumably run the slon
processes managing both nodes on CLI.
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