Hello.

I've read the concept document of Slony-I, which says that SYNC events
are generated when the "log action sequence number of the local node has
changed". The first time I read this, I assumed that only nodes that own
a set generate SYNC events, and that would happen only when the data
changed. But by looking at the logs and at the slon source code, I see
that SYNC events are generated every 10 seconds (I know this is
configurable). The documentation for the slon daemon also mentions that
sync events are generated on slave nodes and that "these SYNC events are
of not terribly much value".

So why generate sync events on slave nodes at all? Processing an event
is quite expensive, AFAIK it scales O(N^2) with the number of nodes, so
it seems like a waste of CPU time and bandwidth. Is there any useful
purpose for these periodic SYNC events?

Cheers,
Nuno Santos