1.Btree root node :
min : 2 children
max : n children
2.Btree internal node:
min : ceil(n/2) children
max : n children
3.Btree leaf node : 0 children
4. B+tree root node :
min : 2 children
max : n children
5. B+tree internal node:
min : ceil(n/2) children
max : n children
6.B+tree node:
min 0 children
max 0 children