High index tential is when there's a lot of rows being filtered versus the amount being scanned. If you've got an index scan that's still having to filter out a lots of rows, that we call that an inefficient index. In post gress, one of the things that it gets beaten with isteifit is its effectively its equivalent of garbage collection. It ends up bloating the tables and the indexes a little bit,. sometimes a lot, which is a problem.