Optimize LEFT JOINS ORDER BY on multiple varchar columns

I tried to optimize a MySQL query which sort multiple varchar columns:

SELECT *
FROM tickets
LEFT OUTER JOIN customers ON customers.id 开发者_如何学编程= tickets.customer_id
LEFT OUTER JOIN locations ON locations.id = tickets.location_id
ORDER BY customers.name, locations.name;

The ORDER BY statement seems to cost lot of time(~100ms) for a small database of ~6000 tickets, ~40 customers and ~400 locations.

I already reduced the length of varchar columns, which had significantly speed up the query(2x faster).

Do you have any solutions to optimize the query execution time?

Many thanks!

You should have indexes on the customers.name and locations.name columns.

Additionally, ensure that customers.id, tickets.customer_id, locations.id, and tickets.location_id are all indexed.