What are the differences between B trees and B+ trees?
In a b-tree you can store both keys and data in the internal and leaf nodes, but in a b+ tree you have to store the data in the leaf nodes only.
Is there any advantage of doing the above in a b+ tree?
Why not use b-trees instead of b+ trees everywhere, as intuitively they seem much faster?
I mean, why do you need to replicate the key (data) in a b+ tree?
Answer
The image below helps show the differences between B+ trees and B trees.
Advantages of B+ trees:
- Because B+ trees don't have data associated with interior nodes, more keys can fit on a page of memory. Therefore, it will require fewer cache misses in order to access data that is on a leaf node.
- The leaf nodes of B+ trees are linked, so doing a full scan of all objects in a tree requires just one linear pass through all the leaf nodes. A B tree, on the other hand, would require a traversal of every level in the tree. This full-tree traversal will likely involve more cache misses than the linear traversal of B+ leaves.
Advantage of B trees:
- Because B trees contain data with each key, frequently accessed nodes can lie closer to the root, and therefore can be accessed more quickly.
