示例
示例
SELECT /*+ JOIN_ORDER(u, o), NO_INDEX(o idx_status) */
u.name, o.total
FROM users u
JOIN orders o ON o.user_id = u.id
WHERE u.city = 'shanghai';
SELECT /*+ MAX_EXECUTION_TIME(1000) */ COUNT(*)
FROM orders;
SELECT /*+ SET_VAR(sort_buffer_size = 32M) */ *
FROM orders ORDER BY total DESC LIMIT 10;| 位置 | 写在 SELECT/UPDATE/DELETE/INSERT 等关键字之后 |
|---|---|
| MAX_EXECUTION_TIME | 单位毫秒，只作用于只读 SELECT |
| SET_VAR | 语句级临时覆盖指定系统变量 |