Mysql 查询数据库容量大小的方法步骤

查询所有数据库的总大小

方法如下：

mysql> use information_schema;
mysql> select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from TABLES;
+-----------+
| data   |
+-----------+
| 3052.76MB |
+-----------+
1 row in set (0.02 sec)

统计一下所有库数据量

每张表数据量=AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH

SELECT
SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mb
FROM information_schema.TABLES 

统计每个库大小：

SELECT
table_schema,SUM(AVG_ROW_LENGTH*TABLE_ROWS+INDEX_LENGTH)/1024/1024 AS total_mb
FROM information_schema.TABLES group by table_schema;

第二种情况：查看指定数据库的大小，比如说：数据库test，方法如下：

mysql> use information_schema;
mysql> select concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as data from TABLES where table_schema='test';
+----------+
| data   |
+----------+
| 142.84MB |
+----------+
1 row in set (0.00 sec)

查看所有数据库各容量大小

select
table_schema as '数据库',
sum(table_rows) as '记录数',
sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)',
sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)'
from information_schema.tables
group by table_schema
order by sum(data_length) desc, sum(index_length) desc;

查看所有数据库各表容量大小

select
table_schema as '数据库',
table_name as '表名',
table_rows as '记录数',
truncate(data_length/1024/1024, 2) as '数据容量(MB)',
truncate(index_length/1024/1024, 2) as '索引容量(MB)'
from information_schema.tables
order by data_length desc, index_length desc;

查看指定数据库容量大小

例：查看mysql库容量大小
select
table_schema as '数据库',
sum(table_rows) as '记录数',
sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)',
sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)'
from information_schema.tables
where table_schema='mysql';　

查看指定数据库各表容量大小

例：查看mysql库各表容量大小

select
table_schema as '数据库',
table_name as '表名',
table_rows as '记录数',
truncate(data_length/1024/1024, 2) as '数据容量(MB)',
truncate(index_length/1024/1024, 2) as '索引容量(MB)'
from information_schema.tables
where table_schema='mysql'
order by data_length desc, index_length desc;

题外方法

直接用shell命令统计mysql data目录中的大小（注意只有库，不包含数据库日志大小）

备注 ：

data_length ：存储数据大小

data_length/1024/1024：将字节转换为MB

round(sum(data_length/1024/1024),2)：取两位小数

concat(round(sum(data_length/1024/1024),2),'MB') ：给计算结果追加单位 “MB”

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