In some RDBMS a foreign key will automatically create an index: https://dev.mysql.com/doc/refman/8.4/en/create-table-foreign-keys.html#foreign-key-restrictions

In some RDBMS a foreign key will automatically create an index: https://dev.mysql.com/doc/refman/8.4/en/create-table-foreign-keys.html#foreign-key-restrictions https://dev.mysql.com/doc/refman/8.4/en/create-table-foreign... I think this falls under the read the documentation fully point. Edit: It occurs to me you likely meant on the column itself rather than on the referenced column. I don't have an example that does that.