1. Extraction, Transform & Loading
CHAPTER 4

2. WHAT IS ETL TOOL?
 An ETL tool is a tool that reads data from one
or more sources.
 Transforms the data so that it is compatible
with the destination
 Loads the data to the destination

3. DESIRED FEATURES
 Extensible,robust,scalable infrastructure
 Reusability of custom and pre-build functions
 Better utilization of existing hardware
resources
 Faster change contrl & management
 Integrated meta-data management
 Complete development
environment,”WORKS AS YOU THINK”
design metaphor

4. THE ETL PROCESS
 EXTRACT
 TRANSFORM
 CLEANSE
 LOAD

5. EXTRACT
 Operational sources contain reasonable data
 Also contains less valued data
 Hence extraction is important

6. CLEANSING
 Removal of dirty data
 Help of ETL software

7. STEPS IN DATA CLEANSING
 Parsing
 Correcting
 Standardizing
 Matching
 Consolidating
 Data staging

8. TRANSFORM
 Rectifys inconsistency in database
 Changes according to requirements

9. LOADING
 Initial load
 Incremental load
 Full refresh

10. THE ETL PROCESS

11. ETL SUMMARY
 Not a one time event
 Transformation with many different tasks
 Ongoing incremental data loads
 Periodic full refreshes

12. REFRENCES
 1. The Data Warehouse Lifecycle toolkit,
(Ralph Kimball), 2nd edition, Wiley India.
 2. Data Mining Concepts and Techniques,
(Han, Kamber), 2nd edition, Elsevier.
 3. Data warehousing, (Reema Theraja),
Oxford University Press.