Explain the B+ tree?
B+ tree is a type of tree which denotes sorted data in a way that permits for efficient insertion, retrieval and removal of records, each of which is recognized by a key. It is a dynamic, multilevel index, along with maximum and minimum bounds on the number of keys in every index segment (usually called a 'block' or 'node'). In a B+ tree, in contrast to a B-tree, all records are stored at the lowest level of the tree; just only keys are stored in interior blocks.
The primary value of a B+ tree is in storing data for proficient retrieval in a block-oriented storage context. Given a storage system along with a block size of b, a B+ tree that stores a number of keys equal to a multiple of b will be very proficient when compared to a binary search tree (the corresponding data structure for non-block-oriented storage contexts).