What is your experience with using composite indexes in a database?

In my experience working with Go, I have used composite indexes in databases to optimize queries that filter or sort data across multiple fields simultaneously.

A composite index is an index created on multiple columns of a table. It allows the database to efficiently execute queries with conditions on several fields.

For example, if you have a users table with last_name and first_name fields, and you frequently run queries filtering on both fields, creating a composite index (last_name, first_name) will speed up such queries.

In Go, interaction with the database is usually through ORM or SQL drivers, where index creation is done at the database level (e.g., PostgreSQL, MySQL). In your Go code, you can use migrations or SQL queries to create such indexes.

Example SQL for creating a composite index:

CREATE INDEX idx_users_last_first ON users (last_name, first_name);

Using composite indexes can significantly improve the performance of queries with multiple conditions, especially with large volumes of data.