Wednesday, September 29, 2021

ODI - Join component


A join is a slector component that create a join between multiple flows. A join can be located in a dataset or directly in a mapping as a flow component. 

By default, the join condition will be an equi-join between the two atrributes. But we can also do left outer join, right right join , cross or natural joins etc.

Difference between lookup and join:

  • Lookup handles less volume of data where as join handles huge data.
  • Lookup have 1 input link where as join can have multiple source data links.
  • The lookup component gives us some additional functionality compared to a join. We can supply a default value for a key that does not exist in our lookup table. Using a join we might have to do an outer join followed by an expression operator providing a case to replace the NULL from the unmatched key.

Usecase: we will join two tables jobs and job_history based on join condition where jobs.job_id =job_history.job_id and then store them ina  target table.

Implementation steps: 

Step1: I hope you have created model db stores as tables.

Step2: Drag and drop source tables to map and drag and drop join component from component pallete.

Step3: provide the join condition.

Step4: join the target table

Step5: Go to physical tab and provide LKM and IKM and flow control as False.

Save and run it.

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