PostgreSQL 生成列(Generated Columns)与表达式索引实践

创建包含生成列的表： ``` CREATE TABLE orders ( id bigint PRIMARY KEY, amount numeric(12,2) NOT NULL, created_at timestamptz NOT NULL, day date GENERATED ALWAYS AS (created_at::date) STORED, amount_cents integer GENERATED ALWAYS AS (round(amount*100)) STORED ); ``` 为生成列创建索引与查询： ``` CREATE INDEX idx_orders_day ON orders(day); CREATE INDEX idx_orders_amount_cents ON orders(amount_cents); EXPLAIN ANALYZE SELECT count(*) FROM orders WHERE day = current_date; ```