hamsterdb Embedded Storage is an embedded database engine written in ANSI-C. It includes B+Trees with variable length keys and records. It supports in-memory databases and endian-independent files, database cursors, multiple databases in one file, "record number" databases, and duplicate keys. hamsterdb is very fast and highly configurable. It compiles and runs on Unix platforms, Linux, Microsoft Windows, and Windows CE.
OpenLink Virtuoso is a scalable, high-performance SQL-200n compliant object-relational database engine. It provide sophisticated database management for SQL, XML, and RDF. All interaction with Virtuoso occurs via its support of industry standard query languages, protocols, APIs, and data formats such as: ODBC, JDBC, OLE-DB, ADO.NET, XMLA, SQL, SPARQL, XQuery, SOAP, HTTP, WebDAV, SyncML, Atom (Publishing and Syndication), RSS, RDF, and more.
With MetaModel, you use a type-safe SQL-like API for querying any datastore. It is a data access framework providing a common interface for exploration and querying of different types of datastores. It isn't a data mapping framework. Instead, it emphasizes abstraction of metadata and the ability to add data sources at runtime, making MetaModel great for generic data processing applications, but less so for applications modeled around a particular domain.
db4o is an object database for Java and all .NET environments. Its features include ACID transactions, automatic class schema recognition, query-by-example, a S.O.D.A. object querying API, native queries, LINQ support on .NET, callback methods, memory files, cascade-on-delete, multi-threaded access, and Java Webstart and servlet support.
StelsCSV is a JDBC driver that allows performing SQL statements and other JDBC operations upon text files (comma separated, tab-separated, fixed length, etc.). Using this driver, users can easily create a simple database consisting of plain text files. The driver can be used for writing data importing programs and migration tools. It supports most keywords of ANSI SQL92, table joins, INSERT, UPDATE, and DELETE statements, data types, aggregate, converting, string, and user-defined SQL functions.
StelsMDB is a MDB JDBC type 4 driver that allows you to perform SQL queries and other JDBC operations on Microsoft Access database (versions 2000-2010) files. The driver is completely platform-independent and does not require installing additional client or server software to provide access to MDB files. It can be effectively used to create, process, and export Microsoft Access databases in your Java applications. It supports most keywords of ANSI SQL'92, supports inner and outer table joins, supports CREATE, INSERT, UPDATE, and DELETE statements, supports transactions, and supports aggregate, numeric, string, conversion, and user-defined SQL functions.
GetData is a library that provides an API to interface with dirfile databases. The dirfile database format is designed to provide a fast, scalable format for storing and reading binary, synchronously-sampled, time-ordered data. GetData was originally written for the BOOMERanG and BLAST experiments as a data format suitable for use for both quick-look and data reduction. It is now used by many other cosmological and astrophysical experiments including ACT, Planck, Spider, Keck, as well as other projects.
jPersist is an extremely powerful object-relational database persistence API that manages to avoid the need for configuration and annotation; mapping is automatic (A-O/RM). It uses JDBC, and can work with any relational database and any type of connection resource. It uses information obtained from the database to handle mapping between the database and Java objects, so mapping configuration is not needed, and annotation is not needed. In fact, there is no configuration needed at all.