Changing to Remote H2

The following sections describe how to replace the default H2 databases with Remote H2:

Setting up datasource configurations
Creating database tables

H2 is not recommended in production

The embedded H2 database is NOT recommended in enterprise testing and production environments. It has lower performance, clustering limitations, and can cause file corruption failures. Please use an industry-standard RDBMS such as Oracle, PostgreSQL, MySQL, or MS SQL instead.

You can use the embedded H2 database in development environments and as the local registry in a registry mount.

Before you begin

Set up the database as explained in Setting up Remote H2.
Download the H2 database driver and copy it to WSO2 IoT Server by following the steps under Setting up drivers.

Setting up datasource configurations

A datasource is used to establish the connection to a database. By default, WSO2_CARBON_DB datasource is used to connect to the default H2 database, which stores registry and user management data. After setting up the Remote H2 database to replace the default H2 database, either change the default configurations of the WSO2_CARBON_DB datasource, or configure a new datasource to point it to the new database as explained below.

Changing the default WSO2_CARBON_DB datasource

Follow the steps below to change the type of the default WSO2_CARBON_DB datasource.

Edit the default datasource configuration in the <PRODUCT_HOME>/repository/conf/datasources/m aster-datasources.xml file as shown below.

<datasource>
      <name>WSO2_CARBON_DB</name>
      <description>The datasource used for registry and user manager</description>
      <jndiConfig>
           <name>jdbc/WSO2CarbonDB</name>
      </jndiConfig>
      <definition type="RDBMS">
           <configuration>
               <url>jdbc:h2:tcp://localhost/~/registryDB;create=true</url>
               <username>regadmin</username>
               <password>regadmin</password>
               <driverClassName>org.h2.Driver</driverClassName>
               <maxActive>80</maxActive>
               <maxWait>60000</maxWait>
               <minIdle>5</minIdle>
               <testOnBorrow>true</testOnBorrow>
               <validationQuery>SELECT 1</validationQuery>
               <validationInterval>30000</validationInterval>
			   <defaultAutoCommit>false</defaultAutoCommit>
           </configuration>
      </definition>
</datasource>

The elements in the above configuration are described below:

Element	Description
url	The URL of the database. The default port for a DB2 instance is 50000.
username and password	The name and password of the database user
driverClassName	The class name of the database driver
maxActive	The maximum number of active connections that canbeallocated atthesame time from this pool. Enter any negative value to denote an unlimited number of active connections.
maxWait	The maximum number of milliseconds that the pool will wait (when there are no available connections) for a connection to be returned before throwing an exception. You can enter zero or a negative value to wait indefinitely.
minIdle	The minimum number of active connections that can remain idle in the pool without extra ones being created, or enter zero to create none.
testOnBorrow	The indication of whether objects will be validated before being borrowed from the pool. If the object fails to validate, it will be dropped from the pool, and another attempt will be made to borrow another.
validationQuery	The SQL query that will be used to validate connections from this pool before returning them to the caller.
validationInterval	The indication to avoid excess validation, and only run validation at the most, at this frequency (time in milliseconds). If a connection is due for validation, but has been validated previously within this interval, it will not be validated again.
defaultAutoCommit	This property is not applicable to the Carbon database in WSO2 products because auto committing is usually handled at the code level, i.e., the default auto commit configuration specified for the RDBMS driver will be effective instead of this property element. Typically, auto committing is enabled for RDBMS drivers by default. When auto committing is enabled, each SQL statement will be committed to the database as an individual transaction, as opposed to committing multiple statements as a single transaction.

For more information on other parameters that can be defined in the <PRODUCT_HOME>/repository/conf/datasources/master-datasources.xml file, see Tomcat JDBC Connection Pool.

The following elements are available only as a WUM update and is effective from 14th September 2018 (2018-09-14). For more information, see Updating WSO2 Products.
This WUM update is only applicable to Carbon 4.4.11 and will be shipped out-out-the-box with Carbon versions newer than Carbon 4.4.35. For more information on Carbon compatibility, see Release Matrix.

Element	Description
commitOnReturn	If `defaultAutoCommit`=false, then you can set `commitOnReturn`=true, so that the pool can complete the transaction by calling the commit on the connection as it is returned to the pool. However, If `rollbackOnReturn`=true then this attribute is ignored. The default value is false.
rollbackOnReturn	If `defaultAutoCommit`=false, then you can set `rollbackOnReturn`=true so that the pool can terminate the transaction by calling rollback on the connection as it is returned to the pool. The default value is false.

Configuring the connection pool behavior on return
When a database connection is returned to the pool, by default the product rolls back the pending transactions if defaultAutoCommit=true . However, if required you can disable the latter mentioned default behavior by disabling the ConnectionRollbackOnReturnInterceptor, which is a JDBC-Pool JDBC interceptor, and setting the connection pool behavior on return via the datasource configurations by using the following options.

Disabling the ConnectionRollbackOnReturnInterceptor is only possible with the WUM update and is effective from 14th September 2018 (2018-09-14). For more information on updating WSO2 API Manager, see Updating WSO2 Products. This WUM update is only applicable to Carbon 4.4.11.

Configure the connection pool to commit pending transactions on connection return
1. Navigate to either one of the following locations based on your OS.
  - On Linux/Mac OS: <PRODUCT_HOME>/bin/wso2server.sh/
  - On Windows: <PRODUCT_HOME>\bin\wso2server.bat
2. Add the following JVM option:
```
-Dndatasource.disable.rollbackOnReturn=true \
```
3. Navigate to the <PRODUCT_HOME>/repository/conf/datasources/master-datasources.xml file.
4. Disable the defaultAutoCommit by defining it as false.
5. Add the commitOnReturn property and set it to true for all the datasources, including the custom datasources.
```
<datasource>
     ...
     <definition type="RDBMS">
         <configuration>
               ...
			   <defaultAutoCommit>false</defaultAutoCommit>
			   <commitOnReturn>true</commitOnReturn>	
			   ...
         </configuration>
     </definition>
</datasource>
```
Configure the connection pool to rollback pending transactions on connection return
1. Navigate to the <PRODUCT_HOME>/repository/conf/datasources/master-datasources.xml file.
2. Disable the defaultAutoCommit by defining it as false.
3. Add the rollbackOnReturn property to the datasources.
```
<datasource>
     ...
     <definition type="RDBMS">
         <configuration>
               ...
			   <defaultAutoCommit>false</defaultAutoCommit>	
			   <rollbackOnReturn>true</rollbackOnReturn>
			   ...
         </configuration>
     </definition>
</datasource>
```

Configuring new datasources to manage registry or user management data

Follow the steps below to configure new datasources to point to the new databases you create to manage registry and/or user management data separately.

Add a new datasource with similar configurations as the WSO2_CARBON_DB datasource above to the <PRODUCT_HOME>/repository/conf/datasources/ master-datasources.xml file. Change its elements with your custom values. For instructions, see Setting up datasource configurations.
If you are setting up a separate database to store registry-related data, update the following configurations in the <PRODUCT_HOME>/repository/conf/ registry.xml file.
```
<dbConfig name="wso2registry">
	<dataSource>jdbc/MY_DATASOURCE_NAME</dataSource>
</dbConfig>
```
If you are setting up a separate database to store user management data, update the following configurations in the <PRODUCT_HOME>/repository/conf/user-mgt.xml file.
```
<Configuration>
	<Property name="dataSource">jdbc/MY_DATASOURCE_NAME</Property>
</Configuration>
```

Creating database tables

To create the database tables, connect to the database that you created earlier and run the following scripts in H2 shell or web console:

To create tables in the registry and user manager database (WSO2CARBON_DB), use the below script:
```
<PRODUCT_HOME>/dbscripts/h2.sql
```

Follow the steps below to run the script in Web console:

Run the ./h2.sh command to start the Web console.
Copy the script text from the SQL file.
Paste it into the console.
Click Run.
Restart the server.
You can create database tables automatically when starting the product for the first time by using the -Dsetup parameter as follows:
- For Windows: <PRODUCT_HOME>/bin/wso2server.bat -Dsetup
- For Linux: <PRODUCT_HOME>/bin/wso2server.sh -Dsetup
Deprecation of -DSetup

When proper Database Administrative (DBA) practices are followed, the systems (except analytics products) are not granted DDL (Data Definition) rights on the schema. Therefore, maintaining the -DSetup option is redundant and typically unusable. As a result, from January 2018 onwards WSO2 has deprecated the -DSetup option. Note that the proper practice is for the DBA to run the DDL statements manually so that the DBA can examine and optimize any DDL statement (if necessary) based on the DBA best practices that are in place within the organization.