When you use Flashback Database, the flashback data archiver process (FBDA) tracks and stores transactional changes to a table over its lifetime. This way, you can flashback tables to restore them to the way they were at a time in the past.
When a transaction that modifies a tracked table commits, FBDA reads undo blocks in the database buffer cache and undo segments in data files. Then it filters what is relevant to objects that are marked for archival and copies that undo information into the flashback data archive (tablespace) in the data files. FBDA maintains metadata on the current rows and tracks how much data has been archived.
FBDA automatically manages the flashback data archive for space, organization (partitioning tablespaces), and retention. Additionally, FBDA keeps track of how far the archiving of tracked transactions has progressed.
FBDA can run as a thread or as an operating system process.