Lemur Project Cluster

Running Clustered MySQL Applications

MySQL is installed on the front-end node and all current back-end nodes. If you are working with an application (web-based or otherwise), you should not need to modify your code to work with the clustered setup for MySQL.

There are, however, a couple of points to ensure that your database can be seen and is replicated across all nodes:

• when you create a database via the "create database" command, you must create the database across all nodes (i.e. there is no auto-discovery of new databases)
• when you create a new user, you must replicate the user across all of the nodes (no auto-discovery of new users)
• when you create a table in your database, you must use the NDBCLUSTER engine provided with MySQL - as in the following example:

        
      CREATE TABLE testTable (
        i integer
      ) ENGINE=NDBCLUSTER;
  

 
If the three conditions are met above, then the data in the tables created can be read and written to from any of the clustered nodes.