Implementation principle of index in database: B-tree index

The database will use some methods to store, read and modify data. In actual database management, the database will use both B-tree and B tree to store data. Among them, B-tree is used for indexing, and B-tree is used to store actual records. This article introduces the indexing mechanism of B-tree in the database.

B-tree is a B-tree. It is a data structure and an index type of MySQL. The nodes are arranged in a certain order. Store data in form.

The way B-tree stores data is that each node stores keys in ascending order, and each key contains 2 links to the nodes before and after it. The key of the left node is less than or equal to the key of the current node, and the key of the right node is greater than or equal to the key of the current node. If a node has n keys, it has at most n 1 child nodes.

B-tree index speeds up data query. The storage engine does not have to traverse the entire table to find data, it will start from the root node. The root node location does not contain pointers to child nodes; it finds the correct pointer by looking at the values ​​in the child nodes and by determining the upper and lower bounds of the node, making it easier for the storage engine to find the data.

It should be noted that the order of the index will depend on the order of the columns during the table creation process. When a value overlaps, the next value will be used as the sorting standard. Therefore, the arrangement of columns in the index is very important. For best performance, you need to create indexes in different orders for the same columns.

B-tree not only stores the index, but also stores the value associated with the index, which is linked to the actual data record in the database.

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