So When Does An Oracle B-Tree Index Increase In Height ? (Almost Grown)

So when does an Oracle B-Tree index actually increase in height ?

I’ve basically been asked this same question a number of times over the past few days with regard to the discussions on indexes and different block sized tablespaces, so I thought it might be worth quickly sharing the answer to a wider audience.

Imagine a new, empty table and a corresponding new, empty index. At this stage, the index structure basically consists of one, empty block. The index has a BLEVEL of 0 (from DBA_INDEXES) and a HEIGHT of 1 (from INDEX_STATS), yes it can be confusing