Datawarehouse Terminology

Bitmapped Indexing
A family of advanced indexing algorithms that optimize RDBMS query performance by maximizing the search capability of the index per unit of memory and per CPU instruction. Properly implemented, bitmapped indices eliminate all table scans in query and join processing.

Business Model
An object-oriented model that captures the kinds of things in a business or a business area and the relationships associated with those things (and sometimes associated business rules, too). Note that a business model exists independently of any data or database. A data warehouse should be designed to match the underlying business models or else no tools will fully unlock the data in the warehouse

Corporate Data
All the databases of the company. This includes legacy systems, old and new transaction systems, general business systems, client/server databases, data warehouses and data marts.

Data Dictionary
A collection of Metadata. Many kinds of products in the data warehouse arena use a data dictionary, including database management systems, modeling tools, middleware, and query tools.

Data Mart
A subset of a data warehouse that focuses on one or more specific subject areas. The data usually is extracted from the data warehouse and further denormalized and indexed to support intense usage by targeted customers.

Data Mining
Techniques for finding patterns and trends in large data sets. See also Data Visualization.

Data Model
The road map to the data in a database. This includes the source of tables and columns, the meanings of the keys, and the relationships between the tables.

Data Visualization
Techniques for turning data into information by using the high capacity of the human brain to visually recognize patterns and trends. There are many specialized techniques designed to make particular kinds of visualization easy.

Data Warehouse
A database built to support information access. Typically a data warehouse is fed from one or more transaction databases. The data needs to be cleaned and restructured to support queries, summaries, and analyses.

Decision Support
Data access targeted to provide the information needed by business decision makers. Examples include pricing, purchasing, human resources, management, manufacturing, etc.

Decision Support System (DSS)
Database(s), warehouse(s), and/or mart(s) in conjunction with reporting and analysis software optimized to support timely business decision making.

Joint Application Development (JAD)
JAD is a process originally developed for designing a computer-based system. It brings together business area people (users) and IT (Information Technology) professionals in a highly focused workshop. The advantages of JAD include a dramatic shortening of the time it takes to complete a project. It also improves the quality of the final product by focusing on the up-front portion of the development lifecycle, thus reducing the likelihood of errors that are expensive to correct later on.

Metadata
Literally, "data about data." More usefully, descriptions of what kind of information is stored where, how it is encoded, how it is related to other information, where it comes from, and how it is related to your business. A hot topic right now is standardizing metadata across products from different vendors.

Methodology
The steps followed to guarantee repeatability of success. A good methodology is built on top of real world experience.

Middleware
Hardware and software used to connect clients and servers, to move and structure data, and/or to pre-summarize data for use by queries and reports.

Multidimensional Database (MDD)
A DBMS optimized to support multidimensional data. The best systems support standard RDBMS functionality and add high-bandwidth support for multidimensional data and queries. Users that need a lot of slices and dices might appreciate a multidimensional database.

Object Oriented Analysis (OOA)
A process of abstracting a problem by identifying the kinds of entities in the problem domain, the is-a relationships between the kinds (kinds are known as classes, is-a relationships as subtype/supertype, subclass/superclass, or less commonly, specialization/generalization), and the has-a relationships between the classes. Also identified for each class are its attributes (e.g. class Person has attribute Hair Color) and its conventional relationships to other classes(e.g. class Order has a relationship Customer to class Customer.)

Object Oriented Design (OOD)
A design methodology that uses Object Oriented Analysis to promote object reusability and interface clarity.

OLAP
An acronym for On Line Analytical Processing.

On Line Analytical Processing (OLAP)
A common use of a data warehouse that involves real time access and analysis of multidimensional data such as order information.

Performance
Data, summaries, and analyses need to be delivered in a timely fashion. Performance is often a key issue with data warehouses: the right answer isn't worth much if it shows up after the decisions have been made.

Query
A specific atomic request for information from a database.

Rapid Application Development (RAD)
Part of a methodology that specifies incremental development with constant feedback from the customers. The point is to keep projects focused on delivering value and to keep clear and open lines of communication. English is not adequate for specification of computer systems, even small ones. RAD overcomes the limitations of language by minimizing the time between concept and implementation.

Relational On-Line Analytic Processing (ROLAP)
OLAP based on conventional relational databases rather than specialized multidimensional databases.

Replication
A standard technique in data warehousing. For performance and reliability several independent copies are often created of each data warehouse. Even data marts can require replication on multiple servers to meet performance and reliability standards.

Replicator
Any of a class of product that supports replication. Often these tools use special load and unload database APIs and have scripting languages that support automation.

Report
A repeatable, formatted, nonatomic request for information from a database. Usually a report formats and combines several related queries.

Reporting Strategy
A top down collection of methodology, products, plans, and teams that ensure business people can get information reliably, accurately, and understandably. It includes choosing tools matched to the organization's particular needs and existing infrastructure, capturing the business models used by the business people, finding source data, integrating all the above into a data warehouse and/or data marts as needed.

Security
The right data for the right person. Note that a business analyst may need access to summaries of data s/he should not see. Security systems need to make this easy to implement while making sure outsiders or rogue employees do not see data they should not see.

Snowflake Schema
A layering of Star Schema that scales that technique to handle an entire warehouse.

Star Schema
A standard technique for designing the summary tables of a data warehouse. "Fact" tables each join to a larger number of independent "dimension" tables. The tables may be partially denormalized for performance, but most queries will still need to join in one or more of the star tables.

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