# Tiering Partition: Vertical
+ Groups have disjoint key ranges
+ `SSTables` are no longer strictly fixed-size since it based on the the key ranges of the overlapping groups at the next level

![`smart`](LSMTieringPartitionVertical_aa_001_20221021.png)

------------------------------------------------------------
Major issue:
each level contains multiple SSTables with overlapping key ranges that must be ordered properly based on their recency to ensure correctness.