H2 – relational database management system written in Java

H2 is a relational database management system written in Java. It can be embedded in Java applications or run in client-server mode.

The H2 console application lets you access a SQL database using a browser interface.

An embedded web server with a browser based console application is included, as well as command line tools to start and stop a server, backup and restore databases, and a command line shell tool.

Key Features

• Very fast, open source, JDBC API.
• Memory mode.
• Encrypted database, together with other strong security features such as SHA-256 password encryption, encryption functions, and SSL.
• ODBC driver.
• Fulltext search.
• Multi version concurrency.
• Disk based or in-memory databases and tables, read-only database support, temporary tables
• Transaction support (read committed), 2-phase-commit
• Multiple connections, table level locking
• Cost based optimizer, using a genetic algorithm for complex queries, zero-administration
• Scrollable and updatable result set support, large result set, external result sorting, functions can return a result set
• Embedded and server modes; in-memory databases.
• Browser based Console application.
• Small footprint: around 2 MB jar file size.
• SQL support:
  • Support for multiple schemas, information schema.
  • Referential integrity / foreign key constraints with cascade, check constraints.
  • Inner and outer joins, subqueries, read only views and inline views.
  • Triggers and Java functions / stored procedures.
  • Many built-in functions, including XML and lossless data compression.
  • Wide range of data types including large objects (BLOB/CLOB) and arrays.
  • Sequence and autoincrement columns, computed columns (can be used for function based indexes).
  • ORDER BY, GROUP BY, HAVING, UNION, OFFSET / FETCH (including PERCENT and WITH TIES), LIMIT, TOP, DISTINCT / DISTINCT ON (…).
  • Window functions.
  • Collation support, including support for the ICU4J library.
  • Support for users and roles.
  • Compatibility modes for IBM DB2, Apache Derby, HSQLDB, MS SQL Server, MySQL, Oracle, and PostgreSQL.
• Other features:
  • Small footprint (around 2 MB), low memory requirements.
  • Multiple index types (b-tree, tree, hash).
  • Support for multi-dimensional indexes.
  • CSV (comma separated values) file support.
  • Support for linked tables, and a built-in virtual ‘range’ table.
  • Supports the EXPLAIN PLAN statement; sophisticated trace options.
  • Database closing can be delayed or disabled to improve the performance.
  • Web-based Console application (translated to many languages) with autocomplete.
  • The database can generate SQL script files.
  • Contains a recovery tool that can dump the contents of the database.
  • Support for variables (for example to calculate running totals).
  • Automatic re-compilation of prepared statements.
  • Uses a small number of database files.
  • Uses a checksum for each record and log entry for data integrity.
  • Well tested (high code coverage, randomized stress tests).

Website: www.h2database.com
Support: FAQ, GitHub Code Repository
Developer: H2 Developers
License: Eclipse Public License or Mozilla Public License 2.0

H2 is written in Java. Learn Java with our recommended free books and free tutorials.

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