>[info] 评估表数据体量SQL 1. 表容量 表容量主要从表的记录数、平均长度、增长量、读写量、总大小量进行评估。一般对于OLTP的表，建议单表不要超过2000W行数据量，总大小15G以内。访问量：单表读写量在1600/s以内 ``` select count(*) from table select count(1) from table ``` 2. 磁盘空间 查看指定数据库容量大小 ``` 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; ```  查询单个库中所有表磁盘占用大小 ``` 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='zulin' ORDER BY data_length DESC, index_length DESC; ```  建议数据量占磁盘使用率的70%以内。同时，对于一些数据增长较快，可以考虑使用大的慢盘进行数据归档