Have you used anything other than the default index? What is a stored function and procedure?

Besides default indexes (e.g., B-tree), the following are often used:

• Hash indexes — for fast exact match searches.
• GIN and GiST indexes — for full-text search and working with arrays in PostgreSQL.
• Bitmap indexes — for columns with a small number of unique values.

Stored procedure — a set of SQL commands stored in the database and executed as a single unit. It can accept parameters, perform complex logic, and modify data.

Stored function — similar to a procedure but always returns a value and can be used in SQL queries, for example, in SELECT.

Example of a stored function in SQL:

CREATE FUNCTION get_user_count() RETURNS integer AS $$
BEGIN
  RETURN (SELECT COUNT(*) FROM users);
END;
$$ LANGUAGE plpgsql;