B +, B.-tree in MySQL

1. Basic two-tree lookup

The level of each node is 2, so the time complexity of the lookup, O (log2 N)

2.b-Tree

Each node will contain a key array, a point array, and data.

The size of the key is the out-of-size, denoted by D, so the time complexity of the lookup is O (LOGD), so the efficiency

much higher.

3.b+ Tree

The maximum number of points per node is 2d, not 2d+1,

There is no data field on the node, which is more suitable for the external storage index structure.

Many real-world storage systems implement sequential access pointers based on the classic B + tree, where leaf nodes can access adjacent nodes.

4.DB Why use B-(b +) trees inside

Each time you create a new node, you can request a page space to ensure that the size of a page is physically, so that access to a node requires only one IO,

In addition, the complexity of the time is very low.

Reference: http://blog.codinglabs.org/articles/theory-of-mysql-index.html

O(Log2N)O (log2n)

 

B +, B.-tree in MySQL