Intelligence is enhancing the Information Technology architecture
and systems, providing the opportunity for enhanced services and
Large data warehouse
projects are dominating IT strategy today, in spite of standards
and open integration of tools being less than ideal. The sheer size
of such programs of work, means starting now, in an imperfect technology
is essential if companies are to stay competitive in the future.
A data warehouse is the main storage server hosting an organizations
historical data, its corporate memory. It is distinct from operational
or transactional systems supporting the business functions.
The datawarehouse is used to contain the raw data for management's
decision support systems [business intelligence tools].
The main benefit of a data warehouse is that complex queries and
analysis, such as data mining, can be made on organisational information
without slowing down the operational or transactional systems.
A data warehouse can be defined in the following terms:
- Subject-oriented - The data in the database
is organized so that all the data elements relating to the same
real-world event or object are linked together.
- Time-variant - The changes to the data in
the database are tracked and recorded so that reports can be produced
showing changes over time.
- Non-volatile - Data in the database is never
over-written or deleted - once committed, the data is static,
read-only, but retained for future reporting; and
- Integrated - The database contains data from
most or all of an organization's operational applications, and
that this data is made consistent.
While operational systems are optimized for simplicity and speed
of modification [Online Transactional Processing, or OLTP] through
heavy use of database normalization and an entity-relationship model,
the data warehouse is optimized for reporting and analysis [online
analytical processing, or OLAP].
Data in data warehouses are often heavily denormalised, summarised
or stored in a dimension-based model. This is not always required
to achieve acceptable query response times.
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