查看mysql库大小，表大小，索引大小
通过MySQL的 information_schema 数据库，可查询数据库中每个表占用的空间、表记录的行数；该库中有一个 TABLES 表，这个表主要字段分别是：
TABLE_SCHEMA : 数据库名
TABLE_NAME：表名
ENGINE：所使用的存储引擎
TABLES_ROWS：记录数
DATA_LENGTH：数据大小
INDEX_LENGTH：索引大小
其他字段请参考MySQL的手册，查看一个表占用空间的大小，那就相当于是 数据大小 + 索引大小 。
1 查看所有库的大小
mysql> use information_schema;
Database changed
mysql> select concat(round(sum(DATA_LENGTH/1024/1024/1024),2),'G') as data from TABLES;
+--------+
| data |
+--------+
| 54.09G |
+--------+
1 row in set (0.01 sec)
2 查看指定库的大小
use information_schema;
select concat(round(sum(DATA_LENGTH/1024/1024/1024),2),'G') as data from TABLES where table_schema='cps_message';
+---------+
| data |
+---------+
| 26.17MB |
+---------+
1 row in set (0.01 sec)
3 查看指定库的指定表的大小
mysql> select concat(round(sum(DATA_LENGTH/1024/1024/1024),2),'G') as data from TABLES where table_schema='gps_hisData' and table_name='gpsInfo';
+--------+
| data |
+--------+
| 13.38G |
+--------+
1 row in set (0.00 sec)
4 查看指定库的索引大小
mysql> SELECT CONCAT(ROUND(SUM(index_length)/(1024*1024*1024), 2), ' MB') AS 'Total Index Size' FROM TABLES WHERE table_schema = 'cps_message';
+------------------+
| Total Index Size |
+------------------+
| 18.49 MB |
+------------------+
1 row in set (0.00 sec)
5 查看指定库的指定表的索引大小
SELECT CONCAT(ROUND(SUM(index_length)/(1024*1024*1024), 2), ' G') AS 'Total Index Size' FROM TABLES WHERE table_schema = 'gps_hisData' and table_name='gpsInfo';
+------------------+
| Total Index Size |
+------------------+
| 21.84 MB |
+------------------+
1 row in set (0.00 sec)
mysql> show create table gps_hisData.gpsInfo\G;
mysql> select count(*) from gps_hisData.gpsInfo;
+----------+
| count(*) |
+----------+
| 1073607 |
+----------+
1 row in set (0.00 sec)
6 查看一个库中的情况
SELECT CONCAT(table_schema,'.',table_name) AS 'Table Name', CONCAT(ROUND(table_rows/1000000,4),'M') AS 'Number of Rows', CONCAT(ROUND(data_length/(1024*1024*1024),4),'G') AS 'Data Size', CONCAT(ROUND(index_length/(1024*1024*1024),4),'G') AS 'Index Size', CONCAT(ROUND((data_length+index_length)/(1024*1024*1024),4),'G') AS'Total'FROM information_schema.TABLES WHERE table_schema LIKE 'gps_hisData';
+---------------------+----------------+-----------+------------+----------+
| Table Name | Number of Rows | Data Size | Index Size | Total |
+---------------------+----------------+-----------+------------+----------+
| gps_hisData.alarm | 0.1447M | 0.0226G | 0.0363G | 0.0588G |
| gps_hisData.gpsInfo | 98.1350M | 13.3805G | 6.2616G | 19.6421G |
+---------------------+----------------+-----------+------------+----------+
2 rows in set (0.01 sec)
参考网址：
http://www.oschina.net/question/12_3673
http://blog.sina.com.cn/s/blog_4c197d420101fbl9.html