Prefix Key Compression
Important to increase fan-out. (Why?)
Key values in index entries only `direct traffic’; can often compress them.
- E.g., If we have adjacent index entries with search key values Dannon Yogurt, David Smith and Devarakonda Murthy, we can abbreviate David Smith to Dav. (The other keys can be compressed too ...)
- Is this correct? Not quite! What if there is a data entry Davey Jones? (Can only compress David Smith to Davi)
- In general, while compressing, must leave each index entry greater than every key value (in any subtree) to its left.
Insert/delete must be suitably modified.