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15.14.1. MySQL Cluster Changes in MySQL 5.1

A number of new features for MySQL Cluster have been implemented in MySQL 5.1:

  • Integration of MySQL Cluster into MySQL replication: This makes it possible to update from any MySQL Server in the cluster and still have the MySQL Replication handled by one of the MySQL Servers in the cluster, with the state of the slave side remaining consistent with the cluster acting as the master.

    See Section 15.10, “MySQL Cluster Replication”.

  • Support for disk-based records: Records on disk are now supported. Indexed fields including the primary key hash index must still be stored in RAM but all other fields can be on disk.

    See Section 15.11, “MySQL Cluster Disk Data Tables”.

  • Variable-sized records: A column defined as VARCHAR(255) currently uses 260 bytes of storage independent of what is stored in any particular record. In MySQL 5.1 Cluster tables, only the portion of the column actually taken up by the record will be stored. This will make possible a reduction in space requirements for such columns by a factor of 5 in many cases.

  • User-defined partitioning: Users can define partitions based on columns that are part of the primary key. It is possible to partition NDB tables based on KEY and LINEAR KEY schemes. This feature is also available for many other MySQL storage engines, which support additional partitioning types that are not available with NDB Cluster tables.

    For additional general information about user-defined partitioning in MySQL 5.1, see Chapter 16, Partitioning. Specifics of partitioning types are discussed in Section 16.2, “Partition Types”.

    The MySQL Server can also determine whether it is possible to “prune away” some of the partitions from the WHERE clause. See Section 16.4, “Partition Pruning”.

  • Autodiscovery of table schema changes. In MySQL 5.1, you no longer need to issue FLUSH TABLES or a “dummy” SELECT in order for new NDB tables or changes made to schemas of existing NDB tables on one SQL node to be visible on the cluster's other SQL nodes.

    Note: When creating a new database, it is still necessary to issue the CREATE DATABASE or CREATE SCHEMA statement on each SQL node in the cluster.

See MySQL Cluster issues from previous versions that have been resolved in MySQL 5.1 for more information.