data dictionary

A database about data and databases. It holds the name, type, range of values, source, and authorization for access for each data element in the organization's files and databases. It also indicates which application programs use that data so that when a change in a data structure is contemplated, a list of affected programs can be generated.

The data dictionary may be a stand-alone system or an integral part of the DBMS. Data integrity and accuracy is better ensured in the latter case.

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(database)

data dictionary - A data structure that stores meta-data, i.e. data about data. The term "data dictionary" has several uses. Most generally it is a set of data descriptions that can be shared by several applications. Usually it means a table in a database that stores the names, field types, length, and other characteristics of the fields in the database tables. An active data dictionary is automatically updated as changes occur in the database. A passive data dictionary must be manually updated. In a DBMS, this functionality is performed by the system catalog. The data dictionary is a more general software utility used by designers, users, and administrators for information resource management. The data dictionary may maintain information on system hardware, software, documentation, users, and other aspects. Data dictionaries are also used to document the database design process itself and can accumulate meta-data ready to feed into the system catalog.