MySQL 查询缓存的实际应用代码示例

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。

====================================================================

MySQL> select @@query_cache_type; 

+--------------------+ 

| @@query_cache_type | 

+--------------------+ 

| ON |  

+--------------------+ 

MySQL> set query_cache_type=off; 

MySQL> set query_cache_type=on; 

MySQL>  

MySQL> select sql_cache id, title, body from article; 

MySQL> select sql_no_cache id, title, body from article; 

MySQL> show variables like 'have_query_cache'; 

+------------------+-------+ 

| Variable_name | Value | 

+------------------+-------+ 

| have_query_cache | YES |  

+------------------+-------+ 

1 row in set (0.00 sec) 

============================================================================

查看MySQL 查询缓存的大小

MySQL> select @@global.query_cache_size; 

+---------------------------+ 

| @@global.query_cache_size | 

+---------------------------+ 

| 16777216 |  

+---------------------------+ 

1 row in set (0.00 sec) 

MySQL> select @@query_cache_size; 

+--------------------+ 

| @@query_cache_size | 

+--------------------+ 

| 16777216 |  

+--------------------+ 

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。

MySQL> select @@global.query_cache_limit; 

+----------------------------+ 

| @@global.query_cache_limit | 

+----------------------------+ 

| 1048576 |  

+----------------------------+ 

1 row in set (0.00 sec)

========================================================================

碎片整理

MySQL> flush query cache 

-> ; 

Query OK, 0 rows affected (0.00 sec) 

====================================================================

清除缓存

MySQL> reset query cache 

-> ; 

Query OK, 0 rows affected (0.00 sec)

====================================================================

监视MySQL 查询缓存性能：

MySQL> flush tables; 

Query OK, 0 rows affected (0.04 sec) 

MySQL> show status like 'qcache%'; 

+-------------------------+----------+ 

| Variable_name | Value | 

+-------------------------+----------+ 

| Qcache_free_blocks | 1 |  

| Qcache_free_memory | 16768408 |  

| Qcache_hits | 6 |  

| Qcache_inserts | 36 |  

| Qcache_lowmem_prunes | 0 |  

| Qcache_not_cached | 86 |  

| Qcache_queries_in_cache | 0 |  

| Qcache_total_blocks | 1 |  

+-------------------------+----------+ 

8 rows in set (0.06 sec) 

====================================================================

看看当前缓存中有多少条信息：

MySQL> show status like 'qcache_q%'; 

+-------------------------+-------+ 

| Variable_name | Value | 

+-------------------------+-------+ 

| Qcache_queries_in_cache | 0 |  

+-------------------------+-------+ 

1 row in set (0.00 sec) 

MySQL> select sql_cache id, title, body from article; 

MySQL> show status like 'qcache_q%'; 

+-------------------------+-------+ 

| Variable_name | Value | 

+-------------------------+-------+ 

| Qcache_queries_in_cache | 1 |  

+-------------------------+-------+ 

1 row in set (0.00 sec) 

MySQL> show status like 'qcache_f%'; 

+--------------------+----------+ 

| Variable_name | Value | 

+--------------------+----------+ 

| Qcache_free_blocks | 1 |  

| Qcache_free_memory | 16766728 |  

+--------------------+----------+ 

2 rows in set (0.00 sec)