VoltDB is focused on mutating an in-memory dataset at ultra-high speed with full transactions and ACID. SciDB is focused on analyzing petabytes of scientific d

VoltDB is focused on mutating an in-memory dataset at ultra-high speed with full transactions and ACID. SciDB is focused on analyzing petabytes of scientific data in array form, where people care about things like data provenance and accumulated error bounds. Almost polar opposites in use, but similar in philosophy. Both believe specialized systems are the way to handle specialized workloads.