In dynamic lookup transformation, Ignore NULL inputs for updates option works as follows:
When updating Dynamic Lookup cache, Lookup transformation compares each port value of input row with rows from existing lookup cache that meets lookup condition. This is done to determine if the row has to be updated or inserted in the existing cache. If Ignore NULL inputs for updates option is selected for some of the ports, then these ports are ignored when their input values is NULL. Hence, when you have to ignore some of the ports in Lookup transformation (which can have NULL values), select the Ignore NULL inputs for updates option for those ports.
The Ignore NULL inputs for updates option is grayed out for all condition ports since they do not have any NULL input values. If any of the input rows has a NULL in any of the condition port, then that row is ignored by Dynamic lookup cache. And this row is not considered for comparison and is marked NO CHANGE (NewLookupRow = 0).
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FAQ: What happens when a reusable dynamic lookup has new/updated rows and a session fails? How is the dynamic lookup affected? (21787)
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