The data dictionary described in the IBM Dictionary of Computing as “a central repository of information about data, such as value, relationships with other data, their source, application and format.” [1] The term may have one of similar the meaning of the values, referring to databases and DBMS :
- document describing a database or set of databases
- an entire DBMS component necessary to determine its structure
- part of the subroutine software that extends or replaces the built-in DBMS data dictionaries
Content
Data Dictionary Documentation
The data dictionary contains information about the sources, formats and relationships between the data, their descriptions, information about the nature of use and the distribution of responsibility. The data dictionary can be considered as an auxiliary database, which stores information about the main database.
Database users and application developers can benefit from a single, standardized data dictionary document that lists the organization, contents, conventions of one or more databases. [2] This usually includes the names and descriptions of the various tables and fields in each database, additional details such as the type and length of each data item . There is no universal standard that describes the level of detail in such a document, but there is a basic description of metadata about the structure of the database, and not about the data itself. A data dictionary document may also include additional information describing the encoding of data elements. One of the advantages of a well-designed data dictionary is that it helps streamline the structure of a database or a large set of distributed databases . [3]
Data Dictionary as Middleware
In the field of creating database applications, it may be useful to add an additional software layer for the data dictionary, that is, subprogram software that will interact with the underlying database data dictionary. Such a “high-level” data dictionary can provide additional capabilities and a degree of flexibility that will circumvent the limitations of the natural “low-level” data dictionary, whose main purpose is to support the basic functions of a DBMS, rather than the requirements of ordinary applications. For example, a high-level data dictionary may implement alternative ER-models of data adapted for various applications that share common databases. [4] Data dictionary extensions can also help with query optimization in distributed databases . [five]
Platforms designed for rapid application development sometimes contain high-level data dictionary tools that can significantly reduce the importance of software requirements for the development of menus , forms , reports, and other components of database applications, including the databases themselves. For example, PHPLens contains a library of PHP language classes for automating the creation of tables, indexes, and foreign keys that are portable to different databases. [6] Another PHP-based data dictionary is part of the RADICORE utility suite, which automatically creates program objects , scripts and SQL code for menus and forms with data validation and complex associations . [7] Base One International has developed a data dictionary for the ASP.NET platform that provides cross-DBMS capabilities for automated database creation, data validation, performance improvements ( caching and index usage), application security , and additional data types . [eight]
Links
- ↑ ACM, IBM Dictionary of Computing , 10th edition, 1993
- ↑ TechTarget, SearchSOA , What is a data dictionary?
- ↑ AHIMA Practice Brief, Guidelines for Developing a Data Dictionary , Journal of AHIMA 77, no.2 (February 2006): 64A-D.
- ↑ DBMS with active data dictionary , 11/19/1985, AT&T
- ↑ Automated query optimization method using global and parallel local optimizations to provide planning for distributed databases , 02/28/1985, Honeywell Bull
- ↑ PHPLens, ADOdb Library of Data Dictionary for PHP Archived November 7, 2007 on the Wayback Machine
- ↑ RADICORE, What is a data dictionary?
- ↑ Base One International Corp., Base One Data Dictionary
Additional Sources
- Yourdon, Structured Analysis Wiki , Data Dictionaries