SQL query that shows the benefits of BCTTo see how much you benefit from having Block Change Tracking enabled, use this query to calculate the percentage of blocks read and the number of blocks backed up during incremental backups.
For results to show up, you need to have Block Change Tracking enabled and have performed an incremental level 0 backup followed by one or more incremental level 1 backups.
The query returns one row for each datafile backed up using RMAN.
select file#, avg(datafile_blocks) blocks,
group by file#
order by file#