| 用途 | 真实执行计划 |
|---|---|
| 语法 | EXPLAIN ANALYZE SELECT … |
| 输出 | actual time / rows / loops + 估算对比 |
诊断示例
诊断示例
EXPLAIN ANALYZE
SELECT o.id, o.amount, u.name
FROM orders o JOIN users u ON u.id = o.user_id
WHERE o.status = 'paid' AND o.created_at >= '2026-09-01'
ORDER BY o.created_at DESC LIMIT 50;配合慢日志定位
配合慢日志定位
SELECT start_time, query_time, rows_examined, rows_sent, sql_text
FROM mysql.slow_log ORDER BY query_time DESC LIMIT 10;估算 rows 与实际 rows 差异巨大时，先 ANALYZE TABLE 刷统计信息，再评估统计信息采样参数。