Data Warehouse
Architecture, Concepts and Components
What is Data warehouse?
Data
warehouse is an information system that contains historical and commutative
data from single or multiple sources. It simplifies reporting and analysis
process of the organization.
It
is also a single version of truth for any company for decision making and
forecasting.
Characteristics of Data warehouse
A
data warehouse has following characteristics:
- Subject-Oriented
- Integrated
- Time-variant
- Non-volatile
Subject-Oriented
A
data warehouse is subject oriented as it offers information regarding a theme
instead of companies' ongoing operations. These subjects can be sales,
marketing, distributions, etc.
A
data warehouse never focuses on the ongoing operations. Instead, it put
emphasis on modeling and analysis of data for decision making. It
also provides a simple and concise view around the specific subject by
excluding data which not helpful to support the decision process.
Integrated
In
Data Warehouse, integration means the establishment of a common unit of measure
for all similar data from the dissimilar database. The data also needs to be
stored in the Data warehouse in common and universally acceptable manner.
A
data warehouse is developed by integrating data from varied sources like a
mainframe, relational databases, flat files, etc. Moreover, it must keep
consistent naming conventions, format, and coding.
This
integration helps in effective analysis of data. Consistency in naming
conventions, attribute measures, encoding structure etc. have to be ensured.
Consider the following example:
In
the above example, there are three different application labeled A, B and C.
Information stored in these applications are Gender, Date, and Balance.
However, each application's data is stored different way.
- In Application A gender field
store logical values like M or F
- In Application B gender field
is a numerical value,
- In Application C application,
gender field stored in the form of a character value.
- Same is the case with Date and
balance
However,
after transformation and cleaning process all this data is stored in common
format in the Data Warehouse.
Time-Variant
The
time horizon for data warehouse is quite extensive compared with operational
systems. The data collected in a data warehouse is recognized with a particular
period and offers information from the historical point of view. It contains an
element of time, explicitly or implicitly.
One
such place where Datawarehouse data display time variance is in in the
structure of the record key. Every primary key contained with the DW should
have either implicitly or explicitly an element of time. Like the day, week
month, etc.
Another
aspect of time variance is that once data is inserted in the warehouse, it
can't be updated or changed.
Non-volatile
Data
warehouse is also non-volatile means the previous data is not erased when new
data is entered in it.
Data
is read-only and periodically refreshed. This also helps to analyze historical
data and understand what & when happened. It does not require transaction
process, recovery and concurrency control mechanisms.
Activities
like delete, update, and insert which are performed in an operational
application environment are omitted in Data warehouse environment. Only two
types of data operations performed in the Data Warehousing are
1.
Data loading
2.
Data access
Here,
are some major differences between Application and Data Warehouse
Operational Application
|
Data Warehouse
|
Complex program must be coded to make sure
that data upgrade processes maintain high integrity of the final product.
|
This kind of issues does not happen because
data update is not performed.
|
Data is placed in a normalized form to
ensure minimal redundancy.
|
Data is not stored in normalized form.
|
Technology needed to support issues of
transactions, data recovery, rollback, and resolution as its deadlock is
quite complex.
|
It offers relative simplicity in technology.
|
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