Write short notes: B tree
B tree:
A B-tree is a tree structure where every node corresponds to a disk page and which satisfies the following properties:
A special case of the B-tree is when B = 2. Here every index node must have 2 or 3 or 4 child pointers. This special case is called the 2-3-4 tree. Figure 15.1 shows an example of a B-tree. In particular, it’s a 2-3-4 tree.
In the figure, every index node contains between 2 and 4 child pointers, and every leaf node contains between 2 and 4 objects. The root node A is an index node. Currently it has one object with key=25 and two child pointers. In the left sub-tree, every object has key25. Every leaf node (D through I) are located at the same depth: their distance to A is 2. Currently, there are two pages which are full: an index node B and a leaf node D.
What do you mean by ‘Ternary Relationship’? Define the concept of aggregation with suitable example.
State the steps involved in query processing. Why is the query optimization needed?
Explain Sequence and Activity diagram with example.