# B-Tree

Learn about the use cases and the mechanics of B-tree insertion, deletion, and search patterns.

## We'll cover the following

## Introduction

A **B-tree** is an extension of the balanced binary search tree. It addresses the shortcomings of balanced BST, making it suitable for on-disk data structures.

A B-Tree is also called an **m-way** (or **multi-way**) tree. Every node in the B-tree can accommodate M-1 keys and M pointers to child nodes. These keys are called **separators**. A B-tree keeps the keys sorted in ascending order and allows for a binary search:

The first child pointer in the node points to the subtree that holds keys lesser than the first key.

The last child pointer in the node references the subtree with keys greater than or equal to the final key.

Child pointers (other than the first and last in the node) point to the subtree holding keys between the two key ranges

**Key**$_i$ $_-$ $_1$ **< Keys <= Key**$_i$ .

The **order** of a B-tree is the maximum number of children a given B-tree can hold.

Every node in a B-tree belongs to one of three types:

**Root node:**Top of the tree with no parent.**Leaf nodes:**Bottom of the tree with no children.**Internal nodes:**Multilayered and connect the root with the leaves.

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