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2.3.10. The NdbDictionary Class

Abstract

This class provides meta-information about database objects, such as tables, columns, and indexes.

While the preferred method of database object creation and deletion is through the MySQL Server, NdbDictionary also permits the developer to perform these tasks via the NDB API.

Parent class.  None

Child classes.  Dictionary, Column, Object

Description.  This is a data dictionary class that supports enquiries about tables, columns, and indexes. It also provides ways to define these database objects and to remove them. Both sorts of functionality are supplied via inner classes that model these objects. These include the following:

  • NdbDictionary::Object::Table for working with tables

  • NdbDictionary::Column for creating table columns

  • NdbDictionary::Object::Index for working with secondary indexes

  • NdbDictionary::Dictionary for creating database objects and making schema enquiries

  • NdbDictionary::Object::Event for working with events in the cluster.

Additional NdbDictionary::Object subclasses model the tablespaces, logfile groups, datafiles, and undofiles required for working with MySQL Cluster Disk Data tables (introduced in MySQL 5.1).

Warning

Tables and indexes created using NdbDictionary cannot be viewed from the MySQL Server.

Dropping indexes via the NDB API that were created originally from a MySQL Cluster causes inconsistencies. It is possible that a table from which one or more indexes have been dropped using the NDB API will no longer be usable by MySQL following such operations. In this event, the table must be dropped, and then re-created using MySQL to make it accessible to MySQL once more.

Methods.  NdbDictionary itself has no public methods. All work is accomplished by accessing its subclasses and their public members.

NdbDictionary Subclass Hierarchy.  This diagram shows the hierarchy made up of the NdbDictionary class, its subclasses, and their enumerated datatypes:

Diagram showing relationships of the NdbDictionary class, its subclasses, and their enumerated datatypes.

The next several sections discuss NdbDictionary's subclasses and their public members in detail. The organisation of these sections reflects that of the NdbDictionary class hierarchy.

Note

For the numeric equivalents to enumerations of NdbDictionary subclasses, see the file /storage/ndb/include/ndbapi/NdbDictionary.hpp in the MySQL Cluster source tree.