Best way to identify orphan data? I have a few dozen tables, that have data in them, both for the core set of data, and then the company specific data.

I can never delete the core set of data, that is global for all companies.

But i want to be able to help identify orphan data.

Data that is inactive, but hasn't been deleted.

I do not need a query, I can figure that out myself.

Just some ideas on best practices, to help identify then get rid of orphan data, which hopefully will trim the database size down.

Thanks
I would suggest duplicating the table structure in a different schema (backup) and move the data from the one table to the other. That way it can be managed effectively. But if you know what's orphaned, then why would you keep it? What purpose will it serve?