MySQL Server offers a number of choices in storage engines. Since both NDBCLUSTER and InnoDB can serve as transactional MySQL storage engines, users of MySQL Server sometimes become interested in MySQL Cluster. They see NDB as a possible alternative or upgrade to the default InnoDB storage engine in MySQL 5.5. While NDB and InnoDB share common characteristics, there are differences in architecture and implementation, so that some existing MySQL Server applications and usage scenarios can be a good fit for MySQL Cluster, but not all of them.

In this section, we discuss and compare some characteristics of the NDB storage engine used by MySQL Cluster with InnoDB used in MySQL 5.1 and MySQL 5.5. The next few sections provide a technical comparison. In many instances, decisions about when and where to use MySQL Cluster must be made on a case-by-case basis, taking all factors into consideration. While it is beyond the scope of this documentation to provide specifics for every conceivable usage scenario, we also attempt to offer some very general guidance on the relative suitability of some common types of applications for NDB as opposed to InnoDB backends.

While it is possible to use InnoDB tables with MySQL Cluster, such tables are not clustered. MySQL Cluster NDB 7.1 releases use a mysqld based on MySQL 5.1 which includes InnoDB 1.0; MySQL Cluster NDB 7.2.1 and later are based on MySQL Server 5.5, which includes support for InnoDB 1.1. It is also not possible to use programs or libraries from a MySQL Cluster NDB 6.x or MySQL Cluster NDB 7.x distribution with MySQL Server 5.1 or MySQL Server 5.5, or the reverse.

While it is also true that some types of common business applications can be run either on MySQL Cluster or on MySQL Server (most likely using the InnoDB storage engine), there are some important architectural and implementation differences. Section 17.1.5.1, “Differences Between the NDB and InnoDB Storage Engines”, provides a summary of the these differences. Due to the differences, some usage scenarios are clearly more suitable for one engine or the other; see Section 17.1.5.2, “NDB and InnoDB Workloads”. This in turn has an impact on the types of applications that better suited for use with NDB or InnoDB. See Section 17.1.5.3, “NDB and InnoDB Feature Usage Summary”, for a comparison of the relative suitability of each for use in common types of database applications.

For information about the relative characteristics of the NDB and MEMORY storage engines, see When to Use MEMORY or MySQL Cluster.

See Chapter 14, Storage Engines, for additional information about MySQL storage engines.