如果想查看 Mysql 數據庫的總的數據量或者某個表的數據或者索引大小,可以使用系統庫 information_schema 來查詢,這個系統庫中有一個 TABLES 表,這個表是用來記錄數據庫中表的大小、行數、索引大小等信息
mysql > use information_schema; Database changed mysql > show create table TABLES; mysql > desc TABLES;
表結構如下:
sql:
CREATE TEMPORARY TABLE `TABLES` ( `TABLE_CATALOG` varchar(512) NOT NULL DEFAULT '', `TABLE_SCHEMA` varchar(64) NOT NULL DEFAULT '', `TABLE_NAME` varchar(64) NOT NULL DEFAULT '', `TABLE_TYPE` varchar(64) NOT NULL DEFAULT '', `ENGINE` varchar(64) DEFAULT NULL, `VERSION` bigint(21) unsigned DEFAULT NULL, `ROW_FORMAT` varchar(20) DEFAULT NULL, `TABLE_ROWS` bigint(21) unsigned DEFAULT NULL, `AVG_ROW_LENGTH` bigint(21) unsigned DEFAULT NULL, `DATA_LENGTH` bigint(21) unsigned DEFAULT NULL, `MAX_DATA_LENGTH` bigint(21) unsigned DEFAULT NULL, `INDEX_LENGTH` bigint(21) unsigned DEFAULT NULL, `DATA_FREE` bigint(21) unsigned DEFAULT NULL, `AUTO_INCREMENT` bigint(21) unsigned DEFAULT NULL, `CREATE_TIME` datetime DEFAULT NULL, `UPDATE_TIME` datetime DEFAULT NULL, `CHECK_TIME` datetime DEFAULT NULL, `TABLE_COLLATION` varchar(32) DEFAULT NULL, `CHECKSUM` bigint(21) unsigned DEFAULT NULL, `CREATE_OPTIONS` varchar(255) DEFAULT NULL, `TABLE_COMMENT` varchar(2048) NOT NULL DEFAULT '', `BLOCK_FORMAT` varchar(20) DEFAULT NULL ) ENGINE=MEMORY DEFAULT CHARSET=utf8
這個表的字段很多,常用的字段有下面幾個:
TABLE_SCHEMA: 數據庫名
TABLE_NAME: 表名
ENGINE: 所使用的存儲引擎
TABLES_ROWS: 記錄行數
DATA_LENGTH: 表大小
INDEX_LENGTH: 索引大小
一個表的大小 = 數據量 + 索引大小
1、可以查詢數據庫的數據行數、表空間、索引空間,如下,將 [數據庫名] 替換成你自己的數據庫名即可。
SELECT TABLE_SCHEMA AS '庫名', CONCAT(ROUND(TABLE_ROWS/10000, 2), ' 萬行') AS '行數', CONCAT(ROUND(SUM(DATA_LENGTH)/(1024*1024*1024), 2), ' GB') AS '表空間', CONCAT(ROUND(SUM(INDEX_LENGTH)/(1024*1024*1024), 2), ' GB') AS '索引空間', CONCAT(ROUND(SUM(DATA_LENGTH+INDEX_LENGTH)/(1024*1024*1024),2),' GB') AS'總空間' FROM information_schema.TABLES WHERE TABLE_SCHEMA = [數據庫名];
2、當然也可以不匯總,查詢下各個表的情況進行分析,如下,將 [數據庫名] 替換成你自己的數據庫名即可。
SELECT TABLE_NAME AS '表名', CONCAT(ROUND(TABLE_ROWS/10000, 2), ' 萬行') AS '行數', CONCAT(ROUND(DATA_LENGTH/(1024*1024*1024), 2), ' GB') AS '表空間', CONCAT(ROUND(INDEX_LENGTH/(1024*1024*1024), 2), ' GB') AS '索引空間', CONCAT(ROUND((DATA_LENGTH+INDEX_LENGTH)/(1024*1024*1024),2),' GB') AS'總空間' FROM information_schema.TABLES WHERE TABLE_SCHEMA = [數據庫名] ORDER BY TABLE_ROWS DESC;
3、也可以查詢下某個表的情況,如下,將 [數據庫名] 和 [數據表名] 替換成你自己的數據庫名和數據表名即可。
SELECT TABLE_NAME AS '表名', CONCAT(ROUND(TABLE_ROWS/10000, 2), ' 萬行') AS '行數', CONCAT(ROUND(DATA_LENGTH/(1024*1024*1024), 2), ' GB') AS '表空間', CONCAT(ROUND(INDEX_LENGTH/(1024*1024*1024), 2), ' GB') AS '索引空間', CONCAT(ROUND((DATA_LENGTH+INDEX_LENGTH)/(1024*1024*1024),2),' GB') AS'總空間' FROM information_schema.TABLES WHERE TABLE_SCHEMA = [數據庫名] AND TABLE_NAME = [數據表名] ORDER BY TABLE_ROWS DESC;