Data Warehouses and Backups
Early data warehousing practitioners often overlooked the need to perform backups.
Their belief was that since data for the warehouse was extracted from operational systems,
the warehouses could easily be repopulated from those same systems if needed.
However, as warehouses grew and the transformations needed to create and refresh
them evolved, it became evident that backups of data warehouses were necessary
because the transformation process had grown extremely complicated and timeconsuming.
Today, planning for warehouse availability includes not only an
understanding of how long loading will take, but also backup and recovery operations.
Due to the tactical nature of such warehouses, planning often also includes designs for
high availability, disaster recovery, and lifecycle information management.
238 | Chapter 10: Oracle Data Warehousing and Business Intelligence
Extraction, Transformation, and Loading
The first three requirements described in the previous list are often handled by what
are called ETL tools (for extraction, transformation, and loading).
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