May 17, 2005 at 8:45 pm
I am trying to come up with a basic definition of what data warehousing is, and this is what I have been able to come up with. Does anyone have any ideas to add? Thanks!!!!
In researching about data warehouses, I have found several different definitions. A basic definition is that a data warehouse is “a copy of transaction data specifically structured for query and analysis.” Also, data warehousing market consists of tools, technologies, and methodologies that allow for the construction, usage, management, and maintenance of the hardware and software used for a data warehouse, as well as the actual data itself. Also, a very important item to realize is that data warehousing is not necessarily for the needs of "decision makers" or used in the process of decision making.May 18, 2005 at 12:47 am
BOL has an excellent overview - though it is surprising when you note that the very first line it starts with seems to be in conflict with the definition you found (ie the last line -"....not necessarily for the needs of "decision makers" or used in the process of decision making"
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About Data Warehouses
A data warehouse is often used as the basis for a decision support system. Data warehouses are designed to overcome problems encountered when an organization attempts to perform strategic analysis using the same database that is used for online transaction processing (OLTP).
OLTP systems typically:
Support large numbers of concurrent users who are actively adding and modifying data.
Represent the constantly changing state of an organization but don't save its history.
Contain large amounts of data, including extensive data used to verify transactions.
Have complex structures.
Are tuned to be responsive to transaction activity.
Provide the technology infrastructure to support the day-to-day operations of an organization.
Difficulties often encountered when OLTP databases are used for online analysis include the following:
Analysts do not have the technical expertise required to create ad hoc queries against the complex data structure.
Analytical queries that summarize large volumes of data adversely affect the ability of the system to respond to online transactions.
System performance when responding to complex analysis queries can be slow or unpredictable, providing inadequate support to online analytical users.
Constantly changing data interferes with the consistency of analytical information.
Security becomes more complicated when online analysis is combined with online transaction processing.
Data warehousing provides one of the keys to solving these problems, by organizing data for the purpose of analysis. Data warehouses:
Can combine data from heterogeneous data sources into a single homogenous structure.
Organize data in simplified structures for efficiency of analytical queries rather than for transaction processing.
Contain transformed data that is valid, consistent, consolidated, and formatted for analysis.
Provide stable data that represents business history.
Are updated periodically with additional data rather than frequent transactions.
Simplify security requirements.
Provide a database organized for OLAP rather than OLTP.
A data mart is a special form of data warehouse, typically containing a topic-oriented subset of enterprise data appropriate to a specific business function.
Microsoft® SQL Server™ 2000 provides many essential tools for building data warehouses and data marts, including Data Transformation Services (DTS).
**ASCII stupid question, get a stupid ANSI !!!**
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