| 用途 | 索引清单与选择性评估 |
|---|---|
| 语法 | SHOW INDEX FROM tbl |
| 关键列 | Key_name / Seq_in_index / Cardinality / Index_type |
查看示例
查看示例
SHOW INDEX FROM orders;
SHOW INDEX FROM orders WHERE Key_name='idx_uid_status';统计各表索引数
统计各表索引数
SELECT table_name, COUNT(DISTINCT index_name) AS idx_cnt
FROM information_schema.statistics
WHERE table_schema='appdb'
GROUP BY table_name
ORDER BY idx_cnt DESC;Cardinality 是采样估算，ANALYZE TABLE 后可读性更好；它直接反映索引选择性。