How does Lume know what to fill in on the target table if a record effective end date isn’t in the source system but is a property of when the data was fetched? How does Lume know to update the record effective termination date of a target row when a new row comes along?
Apologies, I misread your earlier question. Lume can only ascertain information from what is given directly or from what assumptions it can make with reasonable confidence. So, in this case, this will not be possible unless there is any information in the start schema where this can be interpolated. If these prior transformations were done in a dbt project, we could extract the information needed for this easily (a dbt project can be integrated and represented as a separate flow within your workspace).
(This type of data modeling is described here: https://www.kimballgroup.com/data-warehouse-business-intelli... )