The agent FTSIncrementalIndexer takes care of indexing Rules, Data and Work in sync. Whenever a rule, data or work instance gets inserted, updated or deleted in the DB, Pega creates an entry in the pr_sys_queue_ftsindexer table for the FTSIncrementalIndexer to consume. The agent runs every 60 seconds and processes the queue items to update the appropriate index.
Since it is an advanced agent , I understand that it executes the activity despite there is an item queued for it or not . But the question is how is an entry made in System-Queue-FTSIndexer class which is mapped tp pr_sys_queue_ftsindexer.