Here in this article i just try out to give an idea about what datawarehouse exactly is.
A datawarehouse is the main repository of a organisations data. It contains data for a large no of years.A datawarehouse mainly contains data for a organisations decision support system.
The data from a datawarehouse can be used for analysis say for eg if it’s the sale of umbrelas the producer can decide how much stock has to be made available for the next rainy season based on the sale statistics from the previous years(data stored in warehouse). This data can be analysed and then a dummy sale report /Statistics and be projected.This is one of the main advantages of a datawarehouse.
Bill Inmon (one of the earliest and most influential practitioners) defined a data warehouse as follows:
Subject-oriented, meaning that 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, meaning that the changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time;
Non-volatile, meaning that data in the database is never over-written or deleted, once committed, the data is static, read-only, but retained for future reporting;
Integrated, meaning that the database contains data from most or all of an organization’s operational applications, and that this data is made consistent.
A datawarehouse is designed to support ad hoc data analysis, inquiry and reporting by end users, without programmers, interactively and online. This is called OnLine Analytical Processing (OLAP), or Multi-Dimensional Analysis.
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