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GeekInterview.com > Interview Questions > Data Warehousing > ETL
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Question: How you capture changes in data if the source system does not have option of storing date/time field in source table from where you need to extract the data?
Answer: The DW database can be Oracle or Teradata. The requirement here is to pull data from source system and ETL need to device a mechanism to identify the changes or new records. The source system can be a legacy system like AS400 application or Mainframe application. List out all such methods of data capture. The ETL can be Informatica, data stage or custom etl code. |
| July 07, 2007 00:05:57 |
#1 |
| Sriram |
Member Since: Visitor Total Comments: N/A |
RE: How you capture changes in data if the source syst...
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Assuming this is a Type1 Dimension or a FACT table on the DWH - Create Date and Update Date will be 2 system dates captured and stored on the Datawarehouse. First time Creation_Dt = Update_Dt. Subsequent edits, While loading from Staging to the DWH, comparing the unique keys of the source data from Staging and DWH, if keys match, then update last update_dt and update other data items. |
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