Why does mysql use b-tree

The main reasons why mysql uses b-tree as the index structure are as follows: 1. Efficient balancing. B-tree is a self-balancing tree data structure that can automatically adjust the tree structure to Maintain balance; 2. Adapt to disk storage characteristics. The node size of B-tree is usually set to be the same as the page size, so that one node can be loaded into the memory for operation; 3. Support range query, each node is based on the key value The sizes are arranged in order; 4. Suitable for random access. Each node contains multiple index items, which can be quickly located according to query conditions.

Operating system for this tutorial: Windows 10 system, MySQL 8 version, Dell G3 computer.

The main reasons why MySQL chooses to use B-tree (balanced tree) as the index structure are as follows:

1. Efficient balance:

   B-tree is a self-balancing tree data structure that can automatically adjust the tree structure to maintain balance. The key value on each node can be divided into multiple intervals, allowing each node to store more index items. This balance ensures that in the worst case, the time complexity of B-tree search, insertion and deletion operations is O(log n).

2. Adapt to disk storage characteristics:

   B-tree is widely used in database indexes because it adapts to disk storage characteristics. The node size of B-tree is usually set to be the same as the page size, so that one node can be loaded into the memory for operation, thereby reducing the number of disk I/O accesses and improving query efficiency. At the same time, the self-balancing feature of B-tree also makes the overhead of maintaining the index relatively small.

3. Support range query:

   B-tree is ordered, and each node is ordered according to the size of the key value. This enables B-tree to easily support range queries, such as greater than a certain value, less than a certain value, within a certain value range, and other query operations.

4. Suitable for random access:

   The balance and orderliness of B-tree make it very efficient when supporting random access. Each node contains multiple index items, and the target index item can be quickly located according to the query conditions without the need for a global scan.

In summary, B-tree, as an efficient self-balancing tree structure, can adapt well to disk storage characteristics and supports efficient range queries and random access. Therefore Selected by MySQL as the index structure.

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