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An Insight To Data Warehouse Testing. By Rohit Agrawal Jan 2013. To Start With. Is the data correct…? Would table Cutomer_fact get loaded ever if Control Table has the following..?
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An Insight To Data Warehouse Testing By Rohit Agrawal Jan 2013
To Start With.. Is the data correct…? Would table Cutomer_fact get loaded ever if Control Table has the following..? What if the DW load frequency is daily and ETL execution time exceeds 24 hrs…?
Agenda • Introduction • Testing Process • Focus Points • Challenges • Best Practices
Introduction To Data Warehouse Testing • What ? • Exhaustive testing of a Data Warehouse during its design and on an on-going basis • Why ? • Organisation decisions depend entirely on the Enterprise data and the data should be of utmost quality • Where ? • Starting from Source till Reporting • When ? • Designing phase till Production
Focus Point-Underlying Data All Customer data from different bank branches are loaded Insert data of Customers with age greater than 60 in senior citizen category Error out the records if Customer does not belong to the Bank
Focus Point-Underlying Data (Cont..) Check February has 29 days in leap years only A row in stage with AccountID=123 has the expected data in DW Zip Code is of 6 digits, State names are properly abbreviated
DW Components Impact of Executing complex queries during data load/ Rendering reports in 30 sec Source system scheduling conflicts Incremental loads as per Audit columns like LastUpdateDate/Incremental Flag
Challenges Voluminous data from heterogeneous sources Data Quality not assured at source Business knowledge. Organisation-wide Enterprise data knowledge may not be feasible Very high cost of quality .This is because, any defect slippage will translate into high cost for the organisation The heterogeneous data sources will be updated asynchronously
Best Practices “If you torture data sufficiently, it will confess to almost anything.”
References White Paper on Data Warehouse Testing- By Manoj Philip Mathen Adventures with Testing BI/DW Application- http://msdn.microsoft.com www.google.com A Comprehensive Approach to Data Warehouse Testing- By Matteo Golfarelli