An In-memory database solution with quickest real time replication

Question

We have a 10 thousand row table that has just 2 columns, a primary key and a second column that keep state. The problem is that we need this state to be replicated across 3 physical locations in the US(about 2000 miles apart), in near real time or as fast as practically possible over a network. Any of the 3 locations can update the state for a given row in this table which should be replicated in near real time to the other 2 locations.

Are there any open source or commercial light weight in-memory database that could help us achieve what we are trying to do. Disk persistence is not that important here.

Answer 1

Check out Redis. Here's the Replication Howto.

Also, if you decide that the DB doesn't absolutely need to be in-memory, it just needs to be fast, you might want to consider CouchDB. It can do continuous replication, which is essentially instant, and all nodes are masters. It has a well-thought-out conflict detection and resolution mechanism. This blog post is a great introduction to the latest and greatest CouchDB replication capabilities.

Answer 2

Though there is no replication support built-in, you can use triggers with an in-memory SQLite database. Within the trigger, use a custom function to communicate the changes to the other sites.