Mysql 查询数据库或数据表中的数据量以及数据大小

 许多数据库的元数据都是存储在mysql中的，例如hive、startrockes，因此可以通过mysql中的“information_schema.TABLES”表来查询对应数据库或对应数据表的具体信息。

1、查询各个数据库中的数据条数和数据大小

SELECTTABLE_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)'FROMinformation_schema.TABLESGROUP BYTABLE_SCHEMAORDER BYsum( data_length ) DESC,sum( index_length ) DESC;

2、查询各个数据表中的数据条数和数据大小

SELECTtable_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)' FROMinformation_schema.TABLES ORDER BYdata_length DESC,index_length DESC;

3、查看指定数据库容量大小

SELECTtable_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)' FROMinformation_schema.TABLES WHEREtable_schema = 'test';

4、查看指定数据库各表容量大小

SELECTtable_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)' FROMinformation_schema.TABLES WHEREtable_schema = 'test' ORDER BYdata_length DESC,index_length DESC;

5、查看指定数据库各表的列数

SELECT TABLE_NAME, COUNT(*) AS COLUMN_COUNTFROM INFORMATION_SCHEMA.COLUMNSWHERE TABLE_SCHEMA = 'test'GROUP BY TABLE_NAME;