SQL Query Optimization

When to use

• The user needs to rewrite a query — remove a function on a column, replace OFFSET paging, avoid SELECT *, or add caching — so it runs efficiently.
• The user has a slow request or report where profiling points at the database, and wants to find and speed up the offending query.
• The user wants to enable and read the MySQL slow query log (or performance_schema) to find the queries costing the most total time.

When NOT to use