H2 is a

relational database management system A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured for ...

written in

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

. It can used as an

embedded database An embedded database system is a database management system (DBMS) which is tightly integrated with an application software; it is embedded in the application (instead of coming as a standalone application). It is a broad technology category that ...

in Java applications or run in client–server mode. The software is available as

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

software

Mozilla Public License The Mozilla Public License (MPL) is a free and open-source weak copyleft license for most Mozilla Foundation software such as Firefox and Thunderbird. The MPL is developed and maintained by Mozilla, which seeks to balance the concerns of bo ...

2.0 or the original

Eclipse Public License The Eclipse Public License (EPL) is a free and open source software license most notably used for the Eclipse IDE and other projects by the Eclipse Foundation. It replaces the Common Public License (CPL) and removes certain terms relating t ...

History

The development of the H2 database engine started in May 2004, and first published in December 2005. The database engine was written by Thomas Mueller. He also developed the Java database engine Hypersonic SQL. In 2001, the Hypersonic SQL project was stopped, and the

HSQLDB HSQLDB (''Hyper SQL Database'') is a relational database management system written in Java. It has a JDBC driver and supports a large subset of SQL-92, SQL:2008, SQL:2011, and SQL:2016 standards. It offers a fast, small (around 1300 kilobytes ...

Group was formed to continue work on the Hypersonic SQL code. The name H2 stands for Hypersonic 2, however H2 does not share code with Hypersonic SQL or HSQLDB. H2 is built from scratch. Version 2.0.x was released in January 2022.

Features

A subset of the

SQL Structured Query Language (SQL) (pronounced ''S-Q-L''; or alternatively as "sequel") is a domain-specific language used to manage data, especially in a relational database management system (RDBMS). It is particularly useful in handling s ...

(Structured Query Language) standard is supported. The main programming APIs are SQL and

JDBC Java Database Connectivity (JDBC) is an application programming interface (API) for the Java (programming language), Java programming language which defines how a client may access a database. It is a Java-based data access technology used for Java ...

, however the database also supports using the

PostgreSQL PostgreSQL ( ) also known as Postgres, is a free and open-source software, free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance. PostgreSQL features transaction processing, transactions ...

ODBC In computing, Open Database Connectivity (ODBC) is a standard application programming interface (API) for accessing database management systems (DBMS). The designers of ODBC aimed to make it independent of database systems and operating systems. An ...

driver by acting like a PostgreSQL server. It is possible to create both in-memory tables, as well as disk-based tables. Tables can be persistent or temporary. Index types are hash table and tree for in-memory tables, and

b-tree In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing fo ...

for disk-based tables. All data manipulation operations are transactional. Table level locking and

multiversion concurrency control Multiversion concurrency control (MCC or MVCC), is a non-locking concurrency control method commonly used by database management systems to provide concurrent access to the database and in programming languages to implement transactional memory. ...

are implemented. The

two-phase commit protocol In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC, ''tupac'') is a type of Atomic commit, atomic commitment protocol (ACP). It is a distributed algorithm that coordinates all the processes that pa ...

is supported as well, but no standard API for distributed transactions is implemented. The security features of the database are: role based access rights, encryption of the password using

SHA-256 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compressi ...

and data using the AES or the Tiny Encryption Algorithm, XTEA. The cryptographic features are available as functions inside the database as well. SSL / TLS connections are supported in the client–server mode, as well as when using the console application. The database supports protection against

SQL injection In computing, SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker). SQL injec ...

by enforcing the use of parameterized statements. In H2, this feature is called 'disabling literals'. Two

full text search In text retrieval, full-text search refers to techniques for searching a single computer-stored document or a collection in a full-text database. Full-text search is distinguished from searches based on metadata or on parts of the original texts ...

implementations are included, a native implementation and one using

Lucene Apache Lucene is a free and open-source search engine software library, originally written in Java by Doug Cutting. It is supported by the Apache Software Foundation and is released under the Apache Software License. Lucene is widely used as a ...

. A simple form of high availability is implemented: when used in the client–server mode, the database engine supports hot failover (this is commonly known as clustering). However, the clustering mode must be enabled manually after a failure. Since version 1.1.111, H2

in-memory database An in-memory database (IMDb, or main memory database system (MMDB) or memory resident database) is a database management system that primarily relies on main memory for computer data storage. It is contrasted with database management systems that e ...

can run inside the

Google App Engine Google App Engine (also referred to as GAE or App Engine) is a cloud computing platform used as a service for developing and hosting web applications. Applications are sandboxed and run across multiple Google-managed servers. GAE supports aut ...

References

External links

* {{Official website, www.h2database.com Cross-platform free software Embedded databases Free computer libraries Free database management systems Java (programming language) libraries Relational database management software for Linux Relational database management systems Serverless database management systems Software using the Mozilla Public License

History

Features

See also

References

External links