On 07/30/2013 10:18 AM, Nicolas Frossard wrote:
> Hello dear Slony-1 users,

>
> I have a simple "one master one slave" scenario but an annoying
> requirement: the master and the slave should be able to be configured at
> different time, without the other node being necessarily reachable...

>
> For example, the following should be possible:
>
> 1- start the master DB (slave DB is not started yet)
> 2- init cluster/create set (only on the master)
> 3- start slon process on the master
> 4- add subscription of slave to the set (only on the master)
>
> ... some time later ...
>
> 5- start the slave DB
> 6- init cluster/create set (only on the slave)
> 7- start slon process on the slave
> 9- add subscription of slave to the set (only on the slave)

That won't work you can't do step 4 until after the store node for the 
slave, step 6.  If you defer step 4 until after step 6 you'll be okay.

Depending on what your *real* constraints are, you might be able to use 
slony log shipping.

You'd have a master database and a slave1 database that you can 
start/initialize at the same time.  You then run slon on slave1 with the 
log shipping/archive directory option so it generates .sql files for 
everything that gets sent to it.

You can then create a dump of the machine with slony1_dump.sh and 
transfer the .sql files to your slave2 as you see fit.   Your slave1 
database might only exist to generate the .sql files and slave2 is the 
slave that isn't reachable at the same time as slave1.





>
> ... now the replication is working !
>
> unfortunately, it seems that it is impossible to correctly
> initialize/configure one node (the master) and then later the other (the
> slave). I have to do it at the same time, and both nodes need to be
> reachable.
>
> Is there way to solve this ? I'm using PostgreSQL 9.2 and Slony-1 2.1.3.
>
> Thank you all !
> Nicolas
>
>
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