On Thu, Oct 22, 2009 at 5:44 PM, Howard Chu <hyc@symas.com
<mailto:hyc@symas.com>> wrote:
In the case of a local, load-balanced cluster of replicas, where the
network latency between DSAs is very low, the natural coalescing of
updates may not occur as often. Still, it would be better if the
updates didn't happen at all. And in such an environment, where the
DSAs are so close together that latency is low, distributing reads
is still cheaper than distributing writes. So, the correct way to
implement this global state is to keep it distributed separately
during writes, and collect it during reads.
I'd think that to indicate the topology you would create some
administrative name, perhaps a simple string "sales west" or "cluster
one" to indicate a topological region, and you would specify for each
DSA which administrative name or topology it is logically part of. Then
this administrative region name + unique identifier of the principal in
question, could be used as a key to hold a simple locked / unlocked
boolean value on the replica's parent.