>[info] 評估表數據體量SQL 1. 表容量 表容量主要從表的記錄數、平均長度、增長量、讀寫量、總大小量進行評估。一般對于OLTP的表，建議單表不要超過2000W行數據量，總大小15G以內。訪問量：單表讀寫量在1600/s以內 ``` select?count(*)?from?table select?count(1)?from?table ``` 2. 磁盤空間 查看指定數據庫容量大小 ``` SELECT `table_schema` AS `數據庫`, `table_name` AS `表名`, `table_rows` AS `記錄數`, TRUNCATE(data_length/1024/1024, 2) AS `數據容量(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; ```  查詢單個庫中所有表磁盤占用大小 ``` SELECT `table_schema` AS `數據庫`, `table_name` AS `表名`, `table_rows` AS `記錄數`, TRUNCATE(data_length/1024/1024, 2) AS `數據容量(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; ```  建議數據量占磁盤使用率的70%以內。同時，對于一些數據增長較快，可以考慮使用大的慢盤進行數據歸檔