When using B-trees, we predetermine an integer t. Good morning fuckers let the bullshit begin shirt. Each inner node of the B-tree (except the root node) has from t-1 to 2t-1 lock. Factor 2 ensures that nodes can be split or combined. With an internal button with 2t-1 locks, we can take the key between the 2t-1 keys inserted into the parent node and divide the remaining 2t-2 keys into two new nodes, each t-1 lock. Similarly, when a node and next node both have t-1 keys, we can combine two nodes with a key from the parent node into a new node with 2t-1 keys. The number of children of a node is equal to the key number of that node plus one. Therefore, the number of children of an internal node is from t to 2t.