按照库名 引擎类型分类统计

文件名：schema_engines.sql

作用：按照库名，引擎类型分类统计 表的总大小，数据总大小，索引总大小，表的数量。

代码：

SELECT table_schema, engine,
        ROUND(SUM(data_length+index_length)/1024/1024) AS total_mb,
        ROUND(SUM(data_length)/1024/1024) AS data_mb,
        ROUND(SUM(index_length)/1024/1024) AS index_mb,
        COUNT(*) AS tables
FROM information_schema.tables
GROUP BY table_schema, engine
ORDER BY 3 DESC;