PostgreSQL 生成列与表达式索引实践

ALTER TABLE orders ADD COLUMN total NUMERIC GENERATED ALWAYS AS (price * quantity) STORED;
CREATE INDEX idx_orders_total ON orders (total);

CREATE INDEX idx_users_lower_name ON users ((lower(name)));
EXPLAIN SELECT * FROM users WHERE lower(name) = 'alice';

总结

生成列适合可派生的稳定表达式，表达式索引可优化函数条件查询，二者结合提升整体性能。