How can I utilize the mul key in MySQL?

192 Asked by AashnaSaito in SQL Server , Asked on Dec 22, 2023

I have recently assigned a task which is related to optimizing a MySQL database that includes multiple joins across different tables. How can I identify and utilize the “mul” key in the database to enhance the performance of query and indexing?

Answered by Amit Sinha

The ‘mul’ key in MySQL is often used when a column is used as a part of multiple indexes. It means that a column is an integral part of a composite index, possibly causing less effective queries because of the increment in complexities.

To solve this particular issue, you may strategies like covering indexes or reviewing the indexes to lessen the occurrence of the “mul” key.

Here is the Instance given to showcase the Checking of columns with the “mul” key by using SQL:-

SELECT table_name, column_name

FROM information_schema.columns

WHERE table_schema = ‘your_database_name’ – Replace ‘your_database_name’ with your actual database name

AND column_key = ‘MUL’;

You can adjust “your_database_name” with the real name of your actual database. This above query will certainly help in Identifying which columns are involved in multiple indexes or mul in your database.

How can I utilize the mul key in MySQL?

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