Skip navigation links

Additional languages
15.12.9 Limitations Relating to Multiple Cluster Nodes »
Section Navigation      [Toggle]

15.12.8. Issues Exclusive to MySQL Cluster

The following are limitations specific to the NDBCLUSTER storage engine:

  • Machine architecture.  The following issues relate to physical architecture of cluster hosts:

    • All machines used in the cluster must have the same architecture. That is, all machines hosting nodes must be either big-endian or little-endian, and you cannot use a mixture of both. For example, you cannot have a management node running on a PowerPC which directs a data node that is running on an x86 machine. This restriction does not apply to machines simply running mysql or other clients that may be accessing the cluster's SQL nodes.

    • Adding and dropping of data nodes.  Online adding or dropping of data nodes is not currently possible. In such cases, the entire cluster must be restarted.

    • Backup and restore between architectures.  It is also not possible to perform a Cluster backup and restore between different architectures. For example, you cannot back up a cluster running on a big-endian platform and then restore from that backup to a cluster running on a little-endian system. (Bug#19255)

  • Online schema changes.  It is not possible to make online schema changes such as those accomplished using ALTER TABLE or CREATE INDEX, as the NDB Cluster engine does not support autodiscovery of such changes. (However, you can import or create a table that uses a different storage engine, and then convert it to NDB using ALTER TABLE tbl_name ENGINE=NDBCLUSTER. In such a case, you must issue a FLUSH TABLES statement to force the cluster to pick up the change.)

  • Binary logging.  MySQL Cluster has the following limitations or restrictions with regard to binary logging:

    • SQL_LOG_BIN has no effect on data operations; however, it is supported for schema operations.

    • MySQL Cluster cannot produce a binlog for tables having BLOB columns but no primary key.

    • Only the following schema operations are logged in a cluster binlog which is not on the mysqld executing the statement:

      • CREATE TABLE

      • ALTER TABLE

      • DROP TABLE

      • CREATE DATABASE / CREATE SCHEMA

      • DROP DATABASE / DROP SCHEMA

See also Section 15.12.9, “Limitations Relating to Multiple Cluster Nodes”.


User Comments

Posted by David Lotts on December 27 2007 8:02pm[Delete] [Edit]

Above it says: "Online schema changes. It is not possible to make online schema changes..."

In our experience with Version 5.0.45:
Sometimes it worked smoothly, but in one instance, we got a corrupted schema in one node. We were altering tables then switching one data node off then the other on, then more alterations. Not something you'd do in a production setting.

Add your own comment.