The minimum locking unit is the row. In the case of a bitmap index, one row holds a bitmap which most often refers to many rows. Locking is therefore less granular than with regular indices. Thus, if multiple threads insert rows with bitmap indices, more waits may occur than if the index were not bitmapped. A single row of a bitmap index references maximally 8192 other rows, most often however the count is much less.

In all other respects, locking and transactional behavior are identical with other indices.