in memory database h2 how long keep connection open?

Question

I am testing currently a H2 DB in memory mode. I set up a connection by

h2Con = DriverManager.getConnection( 
                "jdbc:h2:mem:db1", "SA", "");

I want to some imports with dbunit and set up dbUnits db connection

IDataBaseConnection dBUnitConnection = new DatabaseConnection(h2con);

and the imports which i want to query later

So my question is, in memory mode, when can i close the connection? Normaly i do something like this

try{
   //some sql query
}catch{
   //error handling
}finally{
    if(connection!=null)
        connection.close()
}

But in memory if the connection is closed i loose the data? So should it stay open until i end my program?

Answer 1

Add DB_CLOSE_DELAY=-1 in URL

From H2 documentation:

By default, closing the last connection to a database closes the database. For an in-memory database, this means the content is lost. To keep the database open, add ;DB_CLOSE_DELAY=-1 to the database URL. To keep the content of an in-memory database as long as the virtual machine is alive, use jdbc:h2:mem:test;DB_CLOSE_DELAY=-1.

So you can configure H2 to keep in-memory database intact due to the lifetime of your JVM and then you can connect and disconnect to it as you wish.

So, this:

JdbcDataSource ds = new org.h2.jdbcx.JdbcDataSource();
ds.setURL("jdbc:h2:mem:example_db_");
ds.setUser("scott");
ds.setPassword("tiger");

…becomes this:

JdbcDataSource ds = new org.h2.jdbcx.JdbcDataSource();
ds.setURL("jdbc:h2:mem:example_db_;DB_CLOSE_DELAY=-1"); // ⬅ Add ‘delay’ element to URL.
ds.setUser("scott");
ds.setPassword("tiger");