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GeekInterview.com > Interview Questions > Data Warehousing > Informatica
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Question: Why we use lookup transformations?
Answer: Lookup Transformations can access data from relational tables that are not sources in mapping. With Lookup transformation, we can accomplish the following tasks:Get a related value-Get the Employee Name from Employee table based on the Employee IDPerform Calculation. Update slowly changing dimension tables - We can use unconnected lookup transformation to determine whether the records already exist in the target or not. |
| August 08, 2007 07:40:02 |
#5 |
| siraj.khan |
Member Since: Visitor Total Comments: N/A |
RE: Why we use lookup transformations?
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Look up Transformation is like a set of Reference for the traget table.For example suppose you are travelling by an auto ricksha..In the morning you notice that the auto driver showing you some card and saying that today onwards there is a hike in petrol.so, you have to pay more. So, the card which he is showing is a set of reference for there costumer..In the same way the lookup transformation works.
These are of 2 types :
a) Connected Lookup
b) Un-connected lookup
Connected lookup is connected in a single pipeline from a source to a target where as Un Connected Lookup is isolated with in the mapping and is called with the help of a Expression Transformation. |
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