# Splitting a node in B+ tree with odd number of keys

This and several other resources suggest to “Always a node that gets the middle key from bottom splits, should drop one item for a new middle key”.

To illustrate with an example.

For 5-way B+-tree,

(24, 25, 44, 79) is one of the leaf nodes with its root being (..,24,80,…)

``(..,24,80,...)       \         \          \        (24, 25, 44, 79) ``

After Inserting 40.

The node (24, 25, 40, 44, 79) gets overloaded and has to split.

In such a case, is there any advantage of splitting it as

(24, 25) (40, 44, 79) over (24, 25, 40) (44, 79)

Is this split A

``(..,24, 40, 80,...)                     | \           |  \           |   \     (24, 25)  (40,44, 79) ``

better than this split B?

`` (..,24, 44, 80,...)                      | \            |  \            |   \  (24, 25, 40)  (44, 79) ``

If so, what makes A correct and B wrong, considering that both are satisfying the rules of the B+ tree.

I couldn’t find any resource to back my argument that B is equally correct as A.