FB had to disclose a full list of database tables that contain user identifiers and a list of 'data pipelines' for analytics.
Unsealed court doc, 255 pages, listing 11,051 Hive tables and 1,190 source code files, from the NdCal/US lawsuit via @jason_kint@twitter.com:
https://storage.courtlistener.com/recap/gov.uscourts.cand.327471/gov.uscourts.cand.327471.1085.29.pdf