H2 Database Setup Configuration And Troubleshooting

Primary key strategy

Prefer:

GenerationType.AUTO

instead of:

GenerationType.IDENTITY

This improves compatibility across different H2 versions.

Table naming guidance

Always prefix database table names to avoid conflicts with SQL reserved keywords.

Examples:

• RPS_USER
• APP_ORDER

Avoid generic names such as:

• USER
• ORDER
• MATCH
• GROUP

H2 JDBC driver handling for Open Liberty

When using H2 with Open Liberty, copy the H2 JAR into a Liberty-accessible resources location during the Maven build.

What to check when troubleshooting

If H2 is not loading correctly, verify:

• the H2 JAR is copied during the Maven build
• the fileset path matches the actual location of h2.jar
• the datasource libraryRef matches the declared library id
• JPA uses GenerationType.AUTO
• table names do not conflict with SQL reserved words

A working Maven dependency plugin example is:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <version>3.6.0</version>
    <executions>
        <execution>
            <id>copy-h2</id>
            <phase>package</phase>
            <goals>
                <goal>copy</goal>
            </goals>
            <configuration>
                <artifactItems>
                    <artifactItem>
                        <groupId>com.h2database</groupId>
                        <artifactId>h2</artifactId>
                        <version>${h2.version}</version>
                        <type>jar</type>
                        <overWrite>false</overWrite>
                        <outputDirectory>${project.build.directory}/liberty/wlp/usr/shared/resources</outputDirectory>
                        <destFileName>h2.jar</destFileName>
                    </artifactItem>
                </artifactItems>
            </configuration>
        </execution>
    </executions>
</plugin>

server.xml datasource template

A working H2 datasource template for server.xml is:

<dataSource id="h2DataSource" jndiName="jdbc/h2DataSource">
    <jdbcDriver libraryRef="H2Lib" javax.sql.DataSource="org.h2.jdbcx.JdbcDataSource"/>
    <properties URL="jdbc:h2:${server.config.dir}/data/rpsdb;AUTO_SERVER=TRUE" user="sa" password=""/>
</dataSource>

<library id="H2Lib">
    <fileset dir="${server.config.dir}/../../shared/resources" includes="h2.jar"/>
</library>