An index helps MariaDB (or any database, really) to quickly locate often looked-for data that it will otherwise have to search for by reading through our tables row by row. Creating indexes of often-queried columns in large tables is a basic, but very useful optimization.
Import the ISFDB database as described in the Importing the data exported by mysqldump recipe in Chapter 2, Diving Deep into MariaDB.
Launch the
mysql
command-line client application and connect to theisfdb
database on our MariaDB server.Create an index on the
email_address
column of theemails
table:CREATE INDEX email ON emails(email_address(50));
Show the indexes on the
emails
table with the following command:SHOW INDEX FROM emails\G
The output will look similar to the following screenshot: