howeverthe next item to be inserted does cause splitin fact it causes two of them the second node child is fullso it' splitas shown in figure howeverthe promoted from this splithas no place to go because the root is full thereforethe root must be split as wellresulting in the arrangement of figure notice that throughout the insertion process no node (except the rootis ever less than half fulland many are more than half full as we notedthis promotes efficiency because file access that reads node always acquires substantial amount of data efficiency of -trees because there are so many records per nodeand so many nodes per leveloperations on -trees are very fastconsidering that the data is stored on disk in our phone book example there are , records all the nodes in the -tree are at least half fullso they contain at least records and links to children the height of the tree is thus somewhat less than log (logarithm to the base of )where is , this is so there will be about levels in the tree