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Here are some important Data Warehousing Interview Questions & Answers.

1.What is the difference between datastage and informatica
Ans: The main difference is Vendors. Each one is having plus from their architecture. For Datastage it is a Top-Down approach. Based on the Businees needs we have to choose products.

Main Difference is
In DataStage having
Partition,
parallelism,
File Lookup,
Merge/Funnel.

Informatica:
No concept of partition and parallellism

File lookup caching is really horrible. It will take more time do a lookup with other tables.

There is no concept of merge/Funnel options.Here only available union and union all function.

These are the main differences.

2.What is merge and how it can be done plz explain with simple example taking 2 tables .......
Ans: Merge is used to join two tables.It takes the Key columns sort them in Ascending or descending order.Let us consider two table i.e Emp,Dept.If we want to join these two tables we are having DeptNo as a common Key so we can give that column name as key and sort Deptno in ascending order and can join those two tables.


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