Question

(a) If you have a three-column index named “threeIndex” on (col1, col2, col3) of a table A, show whether the following SQL statement can use “threeIndex”. SELECT * FROM A WHERE col2=val2 AND col3=val3

(b) Explain why the B+ tree enables range query (for example, select tuples whose key values are between keyVal1 and keyVal20)​

Answer 1

Answer:

A B+ tree is an m-ary tree with a variable but often large number of children per node. A B+ tree consists of a root, internal nodes and leaves. The root may be either a leaf or a node with two or more children.