Cego implements a relational and transactional database system with support for the SQL query language. The current release contains the most common database features for basic table manipulation and data retrieval. Indexes, foreign keys, views, and stored procedures are also implemented. Future releases (2.0 and above) will support a multi-node database concept with log file shipping for an automatic database application failover.
XDBM is a database designed specifically to handle XML data. It offers greater speed (since the data is stored in a preparsed format), lower memory usage (since only those parts of the file needed are loaded into memory) and faster searching for XML elements. XDBM can also parse and store plain text XML files. XDBM aims to be as close to the W3's DOM specification as possible. XDBM also comes with utilities for converting between XDBM file format and plain text and for reading XDBM files in less and emacs.
PostGIS adds support for geographic objects to the PostgreSQL object-relational database. In effect, PostGIS "spatially enables" the PostgreSQL server, allowing it to be used as a backend spatial database for geographic information systems (GIS), much like ESRI's SDE or Oracle's Spatial extension.
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.
deltasql is a tool to synchronize databases with source code, which helps to keep database evolution under control. While developing mid-sized or big applications, developers make changes to the data model that go along with changes to the source code. From time to time, branches of source code are done to stabilize the code that will go to production. A sort of data model branch is also needed. deltasql provides a simple way to collect all scripts that change the data model and means to handle data model branches. The deltasql server runs on Apache and is backed by MySQL.
BaseX is a light-weight, high-performance, and scalable XML database system and XPath/XQuery processor, including full support for the W3C Update and Full Text extensions. An interactive and user-friendly GUI frontend gives you great insight into large XML data instances. It is platform independent and works out of the box.
GT.M is a high end platform for developing transaction processing database applications. Individual database files in the terabyte range are supported; a logical database can consist of many files. It provides full support for ACID transactions using a Software Transaction Memory (STM) programming model and optimistic concurrency control. The GT.M data model is hierarchical associative memory (i.e. multi-dimensional arrays) that imposes no restriction on the data types of the indexes or content, nor any restriction on the schema is that imposed by the application. Such databases are also referred to as "document oriented", "schemaless", or "schema-free".
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.