Join | Merge | Lookup |
We can perform four types of Joins in Join Stage. Inner Join Left Outer Join Right Outer Join Full Outer Join | We can perform only two types of Joins in Merge Stage. Inner Join Left Outer Join | We can perform only two types of Joins in Look Stage. Inner Join And Left Outer Join |
There will be a N-Inputs ( In the case of Left, Inner, Right Outer Joins) There will be a 2 Inputs ( In the case of Full Outer Join) | There will be a N-Inputs | There will be a N-Inputs ( In the Case of Normal Stage) 2 Inputs (In the Case of Sparse Look Up ) |
One Output Link | One Output Link | One Output Link |
No Reject Links | N-1 Reject Links | One Reject Link |
Light Memory Usage | Light Memory Usage | Heavy Memory usage |
Key Column Names should be Same. That is Primary record should be same with Secondary Records. | Key Column Names should be Same. That is Primary record should be same with Secondary Records. | Key column names Optional. It should be same in the case of Sparse Look Up |
Primary and secondary records should be in sorted order before this stage | Primary and secondary records should be in sorted order before this stage | In Look Up stage it is Optional. That is all the primary and secondary records no need to be sorted. |
Join vs Merge vs Lookup – Datastage
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