Interview Questions

What is ETL process? How many steps ETL contains? Explain with example

ETL (extract, transform, and load) Testing Interview Questions

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2. What is ETL process? How many steps ETL contains? Explain with example

- ETL stands for Extraction, Transforming and Loading.
- Data is extracted from the source(database servers), and applied for generating business role on it.

The following are the steps involved :
- Define the source [ define the odbc connection to the database source ]
- Define the target [ create the odbc connection to the target database ]
- Create the mapping [ Apply business role here by adding transformations and define the data flow from source to target ]
- Create the session [ Mapping instructions ]
- Create the work flow [ Instructions that run on the sessions ]

ETL Testing Process:

ETL stands for Extract Transformation and Load, It collect the different source data from Heterogeneous System (DB), Transform the data into Data warehouse (Target)
At the Time of Transformation, Data are first transform to Staging Table (temporary table)
Based on Business rules the data are mapped into target table, this process are manually mapped / we configure using ETL Tool
ETL not transformed the Duplicate data
Data Transformation process speed based on Source and Target Data ware House
We need to consider the OLAP(Online Analytic Processing) Structure .Data warehouse Model
Source data consist of (XML,Flat file ,Database.Excel Report.Dataware House
We need to set the validation at time of data transformation like ‘Avoid the ‘NULL’ values in the table, validate the data type as using Tiny int instead of integer .etc
Based on the user requirement, ETL process starts

ETL Testing Process:
Similar to any other testing that lies under Independent Verification and Validation, ETL also go through the same phase.
Business and requirement understanding
Test Estimation
Test planning based on the inputs from test estimation and business requirement
Designing test cases and test scenarios from all the available inputs
Once all the test cases are ready and are approved, testing team proceed to perform pre-execution check and test data preparation for testing
Lastly execution is performed till exit criteria are met
Upon successful completion summary report is prepared and closure process is done.

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