Couchbase Server 2.0 represents a significant advancement in distributed document database technology, focusing on stabilization and resource optimization. Key improvements include the development of Couchstore, a high-throughput, recovery-oriented storage engine rewritten in C for enhanced performance and lower resource usage compared to its Erlang predecessor. This new engine supports high-efficiency data operations by allowing concurrent reads and writes, along with asynchronous indexing and MVCC. Another major feature is the integration of CouchDB's incremental map/reduce views into Couchbase, enhanced for clustering with consistency during rebalance and failover, using a bitmap partition index for efficient query performance. Additionally, the release introduces Cross Data Center Replication (XDCR), enabling geographically dispersed, cluster-aware replication to reduce latency for distant users by bringing data closer to them. This replication system is designed to handle network failures and different cluster topologies, resolving conflicts with a "most edited" rule to ensure data consistency across clusters. With these foundational upgrades, Couchbase Server 2.0 sets the stage for future innovations in database technology.