Hi,

I have the following scenario:
There are 3 web applications in a local network which all have a local copy of the same database. Each of them can alter their local database (just the data, not the structure), and every time that happens the databases of the other applications should be updated immediately.
Are there any solutions out there for that? I found that most tools like slony only mirror one master database to multiple slaves, but I want every database to be able to be the starting point.
There could also be a central syn server, like in subversion..

Greets,
Patrick

Log shipping.

Why does each box have its own database? The point of networked database servers is to eliminate that exact scenario. I imagine the overhead of synchronizing them all will be more than the overhead of using one centralized database.

If there are they wouldn't be free.

What you have is a setup nightmare with three databases. On MySQL with two you could set up master to master replication. One would have to use even primary keys and the other odd. For three I suppose you could start the third servers primary key to a number far above what the other two would reach.

But why do that. If your updating the same tables, have the application servers update to one master and each could read from a different slave.

One practical solution for you to do is to integrate all three web applications into a single computer by using virtualization. The other two computers can be setup for the database servers, a master and slave replication. Or, you could create a high available cluster Mysql.