数据仓库的后端工具

 

Data warehouse systems use back-end tools and utilities to populate and refresh their data (Figure 3.12). These tools and utilities include the following functions:

Data extraction,which typically gathers data frommultiple, heterogeneous, and external sources

Data cleaning, which detects errors in the data and rectifies them when possible

Data transformation, which converts data from legacy or host format to warehouse format

Load, which sorts, summarizes, consolidates, computes views, checks integrity, and builds indices and partitions

Refresh, which propagates the updates from the data sources to the warehouse