Bitsy is a small, fast, embeddable, durable in-memory graph database that implements the Blueprints API. It is an ACID database that recovers cleanly from power failures and crashes. Designed for multi-threaded OLTP applications, Bitsy implements optimistic concurrency control and stores data in human-readable JSON-encoded text files. Common management tasks such as online backups can be done over JMX. The speed and simplicity of Bitsy relies on three design principles: No Seek, No Socket, NoSQL.
nf1db is an in memory database engine with SQL and JDBC interfaces. It supports transactions, commands from the SQL-2003 standard, all major data types, a number of functions, default and null values, auto-increments, constraints, primary and foreign keys, set operations, implicit and explicit joins, nested SELECT statements, quantity limits in SELECT statements, and much more.
Concerted is a highly scalable multivariate in-memory data storage library. It has built in support for multivariate queries and performs well over many styles of workloads. The data is read and stored in various data structures, and the data from data structures written to disk. It is fully ACID compliant, has APIs that abstract details from the user, and provides an easy to use interface. Many different types of indexes are provided along with various systems that provide access for data analytics.