@JamesAnderson
Respectfully disagree... I'd not use Cells / Links for Universal Control Groups functionality.
Typical marketing requirements for Universal (Global) Control Group - all that I have seen - would require, at a very least:
1) That it was persistent and stable over very long periods of time (6 month - 1 year - "forever / undefined"), an need to be robust - accidentally losing and recreating a control group from scratch is absolutely unacceptable
2) That it allowed incremental additions from a portion of new customers, so it won't miss out its share of new customer population throughout the group's lifetime.
3) That it could be used for reporting. One needs to be able to build a report comparing long-term performance of Universal Control Group (as a whole) with Universal Target Group (as a whole).
Storing "static" diagram cells as storage for Universal Control Group in my view does not satisfy any of these 3 requirements... There are lots of ways how the contents of a cell can be cleared or lost, accidentally and not... It includes many kinds of upstream diagram modifications, accidental diagram reruns, using many kinds of MATables cleanup procedures, some scenarios to system restore after failure, etc. And once it's gone, there is essentially no way back. This is not something one can rely on to be a robust and guaranteed storage for 1 a year.
Requirements 2 and 3 will not be satisfied unless Universal Control Group is being materialized to the actual database table. One will need to introduce a customized database table (CDM or CMDM) for the Universal Control Group, and implement a mechanism to
store it there. At this point, it becomes easier to just add this table to the infomap... And there is no more need for a statically linked cell altogether...
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Dmitriy Alergant, Tier One Analytics