[Reprint] The meaning of using BTREE in MySQL index

Indexes are implemented in the storage engine, so the indexes for each storage engine are not necessarily identical, and each storage engine does not necessarily support all index types.

Defines the maximum number of indexes and the maximum index length per table based on the storage engine. All storage engines support at least 16 indexes per table with a total index length of at least 256 bytes.

Most storage engines have a higher limit. There are two types of indexes stored in MySQL: Btree and hash, which are related to the storage engine of the table;

The MyISAM and InnoDB storage engines support only btree indexes; memory and heap storage engines can support hash and btree indexes

B-tree indexes are a way to access and find files (called records or key values) in a database. The b-tree algorithm reduces the intermediate process that is experienced when locating records, thus speeding up the access speed.

A typical example of a b-tree is the node in the hard disk. Compared with memory, hard disk spends a lot of time to access a data element, which is the mechanical part of the hard disk can not read and write data much faster than the memory of pure electronic media. Compared to a two-tuple tree with two branches of a node, B-tree uses nodes of multiple branches (called subtrees) to reduce the number of nodes that are experienced when acquiring records, thus saving access time.

This article is from the "Linux career" blog, so be sure to keep this source http://lvzili.blog.51cto.com/1995527/564260

[Reprint] The meaning of using BTREE in MySQL index