This documentation is for an older version. If you're using the most current version, select the documentation for that version with the version switch in the upper right corner of the online documentation, or by downloading a newer PDF or EPUB file. MySQL Cluster Shared-Memory Connections

MySQL Cluster attempts to use the shared memory transporter and configure it automatically where possible. (In very early versions of MySQL Cluster, shared memory segments functioned only when the server binary was built using --with-ndb-shm.) [shm] sections in the config.ini file explicitly define shared-memory connections between nodes in the cluster. When explicitly defining shared memory as the connection method, it is necessary to define at least NodeId1, NodeId2 and ShmKey. All other parameters have default values that should work well in most cases.


SHM functionality is considered experimental only. It is not officially supported in any current MySQL Cluster release, and testing results indicate that SHM performance is not appreciably greater than when using TCP/IP for the transporter.

For these reasons, you must determine for yourself or by using our free resources (forums, mailing lists) whether SHM can be made to work correctly in your specific case.