以下的文章主要介绍的是MySQL 查询缓存的实际应用代码以及查看MySQL 查询缓存的大小 ，碎片整理，清除缓存以及监视MySQL 查询缓存性能的相关内容的描述，以下就是具体内容的描述，希望在你今后的学习中会有所帮助。

1. MySQL> select @@query_cache_type;
2. +--------------------+
3. | @@query_cache_type |
4. +--------------------+
5. | ON |
6. +--------------------+
7. MySQL> set query_cache_type=off;
8. MySQL> set query_cache_type=on; php100.Com
9. MySQL>
10. MySQL> select sql_cache id, title, body from article;
11. MySQL> select sql_no_cache id, title, body from article;
12. MySQL> show variables like have_query_cache;
13. +------------------+-------+
14. | Variable_name | Value |
15. +------------------+-------+
16. | have_query_cache | YES |
17. +------------------+-------+ phP100.Com
18. 1 row in set (0.00 sec)

　　查看MySQL 查询缓存的大小

1. MySQL> select @@global.query_cache_size;
2. +---------------------------+
3. | @@global.query_cache_size |
4. +---------------------------+
5. | 16777216 |
6. +---------------------------+
7. 1 row in set (0.00 sec)
8. MySQL> select @@query_cache_size;
9. +--------------------+ phP100.Com
10. | @@query_cache_size |
11. +--------------------+
12. | 16777216 |
13. +--------------------+
14. 1 row in set (0.00 sec)

　　查看最大缓存结果，如果结果集大于该数，不缓存。

1. MySQL> select @@global.query_cache_limit;
2. +----------------------------+
3. | @@global.query_cache_limit |
4. +----------------------------+
5. | 1048576 |
6. +----------------------------+
7. 1 row in set (0.00 sec)

　　碎片整理

1. MySQL> flush query cache
2. -> ;
3. Query OK, 0 rows affected (0.00 sec)

　　清除缓存

1. MySQL> reset query cache phP100.Com
2. -> ;
3. Query OK, 0 rows affected (0.00 sec

　　监视MySQL 查询缓存性能：

1. MySQL> flush tables;
2. Query OK, 0 rows affected (0.04 sec)
3. MySQL> show status like qcache%;
4. +-------------------------+----------+
5. | Variable_name | Value |
6. +-------------------------+----------+
7. | Qcache_free_blocks | 1 |
8. | Qcache_free_memory | 16768408 |
9. | Qcache_hits | 6 |
10. | Qcache_inserts | 36 | PhP100.Com
11. | Qcache_lowmem_prunes | 0 |
12. | Qcache_not_cached | 86 |
13. | Qcache_queries_in_cache | 0 |
14. | Qcache_total_blocks | 1 |
15. +-------------------------+----------+
16. 8 rows in set (0.06 sec)

　　看看当前缓存中有多少条信息：

1. MySQL> show status like qcache_q%;
2. +-------------------------+-------+
3. | Variable_name | Value |
4. +-------------------------+-------+
5. | Qcache_queries_in_cache | 0 |
6. +-------------------------+-------+
7. 1 row in set (0.00 sec)