Embedding the Java h2 database programmatically

Question

At the moment we use HSQLDB as an embedded database, but we search for a database with less memory footprint as the data volume grows.

Derby / JavaDB is not an option at the moment because it stores properties globally in the system properties. So we thought of h2.

While we used HSQLDB we created a Server-object, set the parameters and started it. This is described here (and given as example in the class org.hsqldb.test.TestBase).

The question is: Can this be done analogous with the h2 database, too? Do you have any code samples for that? Scanning the h2-page, I did not find an example.

Answer 1

Yes, you can run H2 in embedded mode. You just use the JDBC driver and connect to an embedded url like this (their example):

This database can be used in embedded mode, or in server mode. To use it in embedded mode, you need to:

* Add h2.jar to the classpath
* Use the JDBC driver class: org.h2.Driver
* The database URL jdbc:h2:~/test opens the database 'test' in your user home directory

Example of connecting with JDBC to an embedded H2 database (adapted from http://www.h2database.com/javadoc/org/h2/jdbcx/JdbcDataSource.html ):

import org.h2.jdbcx.JdbcDataSource;
// ...
JdbcDataSource ds = new JdbcDataSource();
ds.setURL("jdbc:h2:˜/test");
ds.setUser("sa");
ds.setPassword("sa");
Connection conn = ds.getConnection();

If you're looking to use H2 in a purely in-memory / embedded mode, you can do that too. See this link for more:

• http://www.h2database.com/html/features.html#in_memory_databases

You just need to use a special URL in normal JDBC code like "jdbc:h2:mem:db1".

Answer 2

From the download, I see that the file tutorial.html has this

import org.h2.tools.Server;
...
// start the TCP Server
Server server = Server.createTcpServer(args).start();
...
// stop the TCP Server
server.stop();

Answer 3

If for some reason you need an embedded H2 database in server mode you can do it either manually using the API at http://www.h2database.com/javadoc/org/h2/tools/Server.html - or by appending ;AUTO_SERVER=TRUE to the database URL.