MySQL creates high-performance indexes

I. Type of index

B-tree Index:

B-tree usually means that later values are stored sequentially, and each leaf page is the same distance from the root.

B-tree indexed columns are stored sequentially, so it's good to look for range data.

The B-tree index is valid for queries of the following types :

Full-value match, match leftmost prefix, match column prefix, match range value, exact match to a column, and range match one column, and only the query that accesses the index

B-tree Index Limits:

If you do not start looking in the leftmost column of the index, you just cannot use the index.

Columns in the index cannot be skipped.

If a range query for a column in a query, all columns just to the right of it cannot use an index-optimized query.

Hash Index:

Hash indexes are based on hash table implementations, and only queries that accurately match all columns of the index are valid.

MySQL creates high-performance indexes