Comdb2 is an open source, highly available clustered RDBMS developed by Bloomberg LP, built on optimistic concurrency control techniques. It provides multiple isolation levels, including Snapshot and Serializable Isolation. Read/Write transactions run on any node, with the client library transparently negotiating connections to lowest cost (latency) node which is available. Comdb2 implements queues for publisher-to-subscriber message delivery. Queues can be combined with table triggers for time-consistent log distribution.
Comdb2 supports the SQLite dialect of SQL with some modifications, and embeds the Lua scripting language. Comdb2 maintains a fork of Berkeley DB to provide the keyâÂÂvalue database backend to SQLite.
Comdb2 architecture was described in detail in this 2016 technical paper.