说明：
数据库实例报空间使用达到80%，就需要确定空间具体用了多少。正常数据库实例占用空间主要包括数据大小、索引大小、binlog。
具体：
1. 查看该数据库实例下所有库大小，得到的结果是以MB为单位（除1024为KB，再除1024为MB），下同
> use information_schema > select table_schema,sum(data_length)/1024/1024 as data_length,sum(index_length)/1024/1024 as index_length,sum(data_length+index_length)/1024/1024 as sum from tables; +--------------------+--------------+--------------+--------------+ | table_schema | data_length | index_length | sum | +--------------------+--------------+--------------+--------------+ | information_schema | 554.23122311 | 163.24804688 | 717.47926998 | +--------------------+--------------+--------------+--------------+ 1 row in set (0.32 sec)
2. 查看该数据库实例下各个库大小
> use information_schema > select table_schema,sum(data_length)/1024/1024 as data_length,sum(index_length)/1024/1024 as index_length,sum(data_length+index_length)/1024/1024 as sum from tables group by table_schema; +--------------------+--------------+--------------+--------------+ | table_schema | data_length | index_length | sum | +--------------------+--------------+--------------+--------------+ | coolnull1 | 0.49992847 | 0.54492188 | 1.04485035 | | coolnull | 13.79830647 | 0.74121094 | 14.53951740 | | coolnull2 | 0.00114059 | 0.05078125 | 0.05192184 | | coolnull3 | 101.22271824 | 1.88183594 | 103.10455418 | | coolnull4 | 14.25625229 | 2.78710938 | 17.04336166 | | information_schema | 0.00000000 | 0.00781250 | 0.00781250 | | mysql | 0.51842022 | 0.08691406 | 0.60533428 | | coolnull5 | 0.79851532 | 0.05175781 | 0.85027313 | | coolnull6 | 16.85469151 | 1.04882813 | 17.90351963 | | zabbix | 404.59375000 | 153.34375000 | 557.93750000 | | zabbix_proxy | 1.68750000 | 2.70312500 | 4.39062500 | +--------------------+--------------+--------------+--------------+ 11 rows in set (0.44 sec)
3. 查看coolnull库各表大小
> use information_schema > select table_name,data_length/1024/1024 as data_length,index_length/1024/1024 as index_length,(data_length+index_length)/1024/1024 as sum from tables where table_schema='coolnull'; +-----------------------+-------------+--------------+------------+ | table_name | data_length | index_length | sum | +-----------------------+-------------+--------------+------------+ | wp_commentmeta | 5.99062729 | 0.20312500 | 6.19375229 | | wp_comments | 2.07605743 | 0.07031250 | 2.14636993 | | wp_links | 0.00066376 | 0.00292969 | 0.00359344 | | wp_options | 0.60661697 | 0.01953125 | 0.62614822 | | wp_postmeta | 0.18944931 | 0.08496094 | 0.27441025 | | wp_posts | 4.82567596 | 0.16503906 | 4.99071503 | | wp_term_relationships | 0.03670979 | 0.08691406 | 0.12362385 | | wp_term_taxonomy | 0.03935623 | 0.03417969 | 0.07353592 | | wp_terms | 0.03020859 | 0.06054688 | 0.09075546 | | wp_usermeta | 0.00271606 | 0.00976563 | 0.01248169 | | wp_users | 0.00022507 | 0.00390625 | 0.00413132 | +-----------------------+-------------+--------------+------------+ 11 rows in set (0.00 sec)
附录：
附录1：information_schema.tables表结构
> desc tables; +-----------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------------+---------------------+------+-----+---------+-------+ | TABLE_CATALOG | varchar(512) | YES | | NULL | | | TABLE_SCHEMA | varchar(64) | NO | | | |数据库名 | TABLE_NAME | varchar(64) | NO | | | |表名 | TABLE_TYPE | varchar(64) | NO | | | | | ENGINE | varchar(64) | YES | | NULL | |表使用的存储引擎 | VERSION | bigint(21) unsigned | YES | | NULL | | | ROW_FORMAT | varchar(10) | YES | | NULL | | | TABLE_ROWS | bigint(21) unsigned | YES | | NULL | |表记录数 | AVG_ROW_LENGTH | bigint(21) unsigned | YES | | NULL | | | DATA_LENGTH | bigint(21) unsigned | YES | | NULL | |数据大小 | MAX_DATA_LENGTH | bigint(21) unsigned | YES | | NULL | | | INDEX_LENGTH | bigint(21) unsigned | YES | | NULL | |索引大小 | DATA_FREE | bigint(21) unsigned | YES | | NULL | | | AUTO_INCREMENT | bigint(21) unsigned | YES | | NULL | | | CREATE_TIME | datetime | YES | | NULL | | | UPDATE_TIME | datetime | YES | | NULL | | | CHECK_TIME | datetime | YES | | NULL | | | TABLE_COLLATION | varchar(32) | YES | | NULL | | | CHECKSUM | bigint(21) unsigned | YES | | NULL | | | CREATE_OPTIONS | varchar(255) | YES | | NULL | | | TABLE_COMMENT | varchar(80) | NO | | | | +-----------------+---------------------+------+-----+---------+-------+ 21 rows in set (0.00 sec)