[mysql@csdba1850 ~]$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or /g.
Your MySQL connection id is 3
Server version: 5.0.45-community MySQL Community Edition (GPL)
Type 'help;' or '/h' for help. Type '/c' to clear the buffer.
mysql> set global query_cache_size = 600000; --设置缓存内存
Query OK, 0 rows affected (0.00 sec)
mysql> set session query_cache_type = ON; --开启查询缓存
Query OK, 0 rows affected (0.00 sec)
mysql> use test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| animals |
| person |
+----------------+
5 rows in set (0.00 sec)
mysql> select count(*) from animals;
+----------+
| count(*) |
+----------+
| 6 |
+----------+
1 row in set (0.00 sec)
--Qcache_hits表示sql查询在缓存中命中的累计次数,是累加值。
mysql> SHOW STATUS LIKE 'Qcache_hits';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Qcache_hits | 0 | --0次
+---------------+-------+
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)