SimpleDBM is a multi-threaded transactional database engine. It has a very small footprint and can be embedded in the address space of an application, or used in network client server mode. It provides a simple programming API that can be learned very quickly. SimpleDBM supports ACID transactions, steal/no-force buffer management, lock-based concurrency, row level locks, b-tree indexes, tables, write ahead log, crash recovery, and deadlock detection.
Redstone Prevalent Storage is minimalistic prevalent storage for Java SE 5.0 that replaces the need for JDBC and an RDBMS for small and mid-sized applications. The library is comprised of an intentionally small set of concise interfaces and classes, and can be suitable for many types of applications where the data storage does not necessarily require an RDBMS. The library is heavily influenced by Prevayler and the Prevayler team (who should receive all credit).
Native XmlDB Query Daemon is a client-server version of the Sleepycat native XML database deployed as an Apache module. The client is a pure Java API, supporting XQuery, XPath, and an Xml:DB API layer. It comes with a graphical admin console. Server binaries are provided for Linux x86 and x86-AMD64; for other platforms, compile from source.
Divmod Axiom is an object-relational database backed by SQLite, the goal of which is to provide an efficient, non-SQL interface to an existing relational database manager. It provides support for common Twisted practices: an Axiom store is also a Twisted IServiceCollection provider, and an implementation of Twisted's IRealm interface is provided. It makes heavy use of plugins and includes a wall-clock scheduler.
Schevo is a next-generation DBMS that focuses on database integrity, rapid development, user interface generation, rich schema definition, and assisted schema evolution. Schevo was designed to address shortcomings in SQL-based relational databases where they do not match well with object-oriented programming languages. Schevo solves this problem by combining relational features with the object-oriented programming language Python. Schevo includes a GUI Navigator that can display a fully interactive interface into any Schevo database, using the metadata available within a Schevo database file.
Itzam/C++ wraps the Itzam database engine with C++ templates for both simple and complex database classes. It supports B-tree, hash table, and sparse matrix indexes with unique or duplicate keys, and includes multithreaded resource locking and atomic file transactions. Complete class documentation is embedded in the source code, and available online and in the distribution archive.
Itzam/Java is a pure Java reimplementation of the Itzam embedded database engine, and it is 100% interoperable with files created by Itzam/Core. Since Itzam/Core is the basis of wrappers written in languages such as C++ and Python, Itzam/Java is compatible with those language libraries as well.
H2 is an SQL database engine written in Java that implements the JDBC API. Embedded, server, and clustering modes are available. A browser based console application is included. The database has strong security features. Disk based and in-memory databases and tables are supported.