What is index in MySQL? What is advantage of index?

In MySQL, an index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time a database table is accessed. Indexes can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records.

Advantages of Indexes in MySQL

1. Improved Query Performance: Indexes significantly enhance the speed of data retrieval operations by allowing the database engine to find and retrieve specific rows much faster than without an index. Instead of scanning every row in a table, an index allows the database to search a smaller, indexed portion of the table, reducing the amount of data that must be processed[1][2][3][5][6][7][9].

2. Efficient Sorting and Filtering: Indexes improve the performance of queries involving sorting and filtering by column values. When a query involves a WHERE clause, indexes help in quickly locating the rows that satisfy the condition, thus speeding up the query execution process[1][2][3][5][6][7][9].

3. Reduced I/O Operations: By facilitating quicker data retrieval, indexes reduce the number of disk I/O operations required to fetch data, which is particularly beneficial in large databases[1][2][3][5][6][7][9].

4. Uniqueness: Indexes like the PRIMARY KEY and UNIQUE indexes enforce uniqueness on the column(s) they are defined on by not allowing duplicate values in those columns. This ensures data integrity[1][2][3][5][6][7][9].

5. Optimized Join Performance: Indexes improve the performance of JOIN operations by quickly locating the joining keys, thereby speeding up queries that involve joining tables[1][2][3][5][6][7][9].

6. Facilitates Full-text Searches: Full-text indexes in MySQL supp...