MySQL数据库如何设置global query_cache_size缓存

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)

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