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MySQL的查询缓存机制(2)_MySQL

程序员文章站 2023-12-28 11:32:10
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  +---------------+-------+
8 rows in set (0.00 sec)

mysql> select count(*) from animals;
+----------+
| count(*) |
+----------+
| 6 |
+----------+
1 row in set (0.00 sec)

mysql> SHOW STATUS LIKE ’Qcache%’;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Qcache_hits | 1 | --表示sql在缓存中直接得到结果,不需要再去解析
+---------------+-------+
8 rows in set (0.00 sec)

mysql> select count(*) from animals;
+----------+
| count(*) |
+----------+
| 6 |
+----------+
1 row in set (0.00 sec)

mysql> select count(*) from animals;
+----------+
| count(*) |
+----------+
| 6 |
+----------+
1 row in set (0.00 sec)

mysql> SHOW STATUS LIKE ’Qcache_hits’;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Qcache_hits | 3 | --上面的sql也是是从缓存中直接取到结果
+---------------+-------+
1 row in set (0.00 sec)

mysql> insert into animals select 9,’testsds’ ; --插入数据后,跟这个表所有相关的sql缓存就会被清空掉
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select count(*) from animals;
+----------+
| count(*) |
+----------+
| 7 |
+----------+
1 row in set (0.00 sec)

mysql> SHOW STATUS LIKE ’Qcache_hits’;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Qcache_hits | 3 | --还是等于3,说明上一条sql是没有直接从缓存中直接得到的
+---------------+-------+
1 row in set (0.00 sec)

mysql> select count(*) from animals;
+----------+
| count(*) |
+----------+
| 7 |
+----------+
1 row in set (0.00 sec)

mysql> SHOW STATUS LIKE ’Qcache_hits’;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Qcache_hits | 4 |
+---------------+-------+
1 row in set (0.00 sec)

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相关标签: mysql 查询

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