Comdb2 is an

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

, highly available clustered

RDBMS A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relation ...

developed by

Bloomberg LP Bloomberg L.P. is a privately held financial, software, data, and media company headquartered in Midtown Manhattan, New York City. It was co-founded by Michael Bloomberg in 1981, with Thomas Secunda, Duncan MacMillan, Charles Zegar, and a ...

, built on

optimistic concurrency control Optimistic concurrency control (OCC), also known as optimistic locking, is a concurrency control method applied to transactional systems such as relational database management systems and software transactional memory. OCC assumes that multiple tran ...

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 SQLite (, ) is a database engine written in the C programming language. It is not a standalone app; rather, it is a library that software developers embed in their apps. As such, it belongs to the family of embedded databases. It is the most ...

dialect of SQL with some modifications, and embeds the

Lua Lua or LUA may refer to: Science and technology * Lua (programming language) * Latvia University of Agriculture * Last universal ancestor, in evolution Ethnicity and language * Lua people, of Laos * Lawa people, of Thailand sometimes referred t ...

scripting language. Comdb2 maintains a fork of

Berkeley DB Berkeley DB (BDB) is an unmaintained embedded database software library for key/value data, historically significant in open source software. Berkeley DB is written in C with API bindings for many other programming languages. BDB stores arbitr ...

to provide the

key–value database A key–value database, or key–value store, is a data storage paradigm designed for storing, retrieving, and managing associative arrays, and a data structure more commonly known today as a ''dictionary'' or ''hash table''. Dictionaries contai ...

backend to SQLite. Comdb2 architecture was described in detail in 2016 technical paper.http://www.vldb.org/pvldb/vol9/p1377-scotti.pdf

See also