Data dictionary

From Wikipedia, the free encyclopedia

Jump to: navigation, search

Not to be confused with Dictionary (data structure).

A data dictionary, or metadata repository, as defined in the IBM Dictionary of Computing, is a "centralized repository of information about data such as meaning, relationships to other data, origin, usage, and format."[1] The term may have one of several closely related meanings pertaining to databases and database management systems (DBMS):

a document describing a database or collection of databases
an integral component of a DBMS that is required to determine its structure
a piece of middleware that extends or supplants the native data dictionary of a DBMS

Contents

1 Documentation
2 Middleware
3 See also
4 References
5 External links

[edit] Documentation

Database users and application developers can benefit from an authoritative data dictionary document that catalogs the organization, contents, and conventions of one or more databases.[2] This typically includes the names and descriptions of various tables and fields in each database, plus additional details, like the type and length of each data element. There is no universal standard as to the level of detail in such a document, but it is primarily a weak kind of data.

[edit] Middleware

In the construction of database applications, it can be useful to introduce an additional layer of data dictionary software, i.e. middleware, which communicates with the underlying DBMS data dictionary. Such a "high-level" data dictionary may offer additional features and a degree of flexibility that goes beyond the limitations of the native "low-level" data dictionary, whose primary purpose is to support the basic functions of the DBMS, not the requirements of a typical application. For example, a high-level data dictionary can provide alternative entity-relationship models tailored to suit different applications that share a common database.[3] Extensions to the data dictionary also can assist in query optimization against distributed databases.[4]

Software frameworks aimed at rapid application development sometimes include high-level data dictionary facilities, which can substantially reduce the amount of programming required to build menus, forms, reports, and other components of a database application, including the database itself. For example, PHPLens includes a PHP class library to automate the creation of tables, indexes, and foreign key constraints portably for multiple databases.[5] Another PHP-based data dictionary, part of the RADICORE toolkit, automatically generates program objects, scripts, and SQL code for menus and forms with data validation and complex JOINs.[6] For the ASP.NET environment, Base One's data dictionary provides cross-DBMS facilities for automated database creation, data validation, performance enhancement (caching and index utilization), application security, and extended data types.[7]

[edit] See also

Metadata
Data modeling
ISO/IEC 11179
Metadata registry
Semantic spectrum
Data hierarchy

[edit] References

^ ACM, IBM Dictionary of Computing, 10th edition, 1993
^ TechTarget, SearchSOA, What is a data dictionary?
^ U.S. Patent 4774661, Database management system with active data dictionary, 19 November 1985, AT&T
^ U.S. Patent 4769772, Automated query optimization method using both global and parallel local optimizations for materialization access planning for distributed databases, 28 February 1985, Honeywell Bull
^ PHPLens, ADOdb Data Dictionary Library for PHP
^ RADICORE, What is a Data Dictionary?
^ Base One International Corp., Base One Data Dictionary

[edit] External links

| Wikimedia Commons has media related to: Data dictionary

Yourdon, Structured Analysis Wiki, Data Dictionaries

v • d • e

Data warehouse

Creating the data warehouse

Concepts

Database · Dimension · Dimensional modeling · Fact · OLAP · Star schema · Aggregate

Variants

Column-oriented DBMS · Data Vault Modeling · HOLAP · MOLAP · ROLAP · Operational data store

Elements

Data dictionary/Metadata · Data mart · Sixth normal form · Surrogate key

Fact

Fact table · Early-arriving fact · Measure

Dimension

Dimension table · Degenerate · Slowly changing

Filling

Extract-Transform-Load (ETL) · Extract · Transform · Load

Using the data warehouse

Concepts

Business intelligence · Dashboard · Data mining · Decision support system (DSS) · OLAP cube

Languages

Data Mining Extensions (DMX) · MultiDimensional eXpressions (MDX) · XML for Analysis (XMLA)

Tools

Business intelligence tools · Reporting software · Spreadsheet

Related

Persons

Bill Inmon · Ralph Kimball

Products

Comparison of OLAP Servers · Data warehousing products and their producers

Retrieved from "http://en.wikipedia.org/wiki/Data_dictionary"

Categories: Data management | Data modeling | Knowledge representation | Metadata

Hidden categories: Use dmy dates from September 2010

Personal tools

Log in / create account

Namespaces

Article

Discussion

Variants

Views

Read

Edit

View history

Actions

Search

Navigation

Main page

Contents

Featured content

Current events

Random article

Donate

Interaction

Help

About Wikipedia

Community portal

Recent changes

Contact Wikipedia

Toolbox

What links here

Related changes

Upload file

Special pages

Permanent link

Cite this page

Print/export

Create a book

Download as PDF

Printable version

Languages

Català

Deutsch

Español

فارسی

Français

한국어

Bahasa Indonesia

日本語

Português

Русский

Türkçe

This page was last modified on 17 November 2010 at 18:11.

Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.

Contact us

Privacy policy

About Wikipedia

Disclaimers