What are PostgreSQL custom operators and how to create them?

Custom operators allow defining new symbols for operations on data types.

Example:

-- Create function first
CREATE FUNCTION add_percent(numeric, numeric)
RETURNS numeric AS $$
BEGIN
    RETURN $1 + ($1 * $2 / 100);
END;
$$ LANGUAGE plpgsql;

-- Create operator
CREATE OPERATOR +% (
    LEFTARG = numeric,
    RIGHTARG = numeric,
    FUNCTION = add_percent
);

-- Usage
SELECT 100 +% 15; -- Returns 115

Benefits:
• Domain-specific syntax
• Improved readability
• Custom data type operations