MySQL 空间碎片的查看与回收

SELECT TABLE_SCHEMA,
       round(SUM(data_length + index_length + DATA_FREE) / 1024 / 1024, 2) AS TOTAL_MB,
       round(SUM(data_length) / 1024 / 1024, 2)                            AS DATA_MB,
       round(SUM(index_length) / 1024 / 1024, 2)                           AS INDEX_MB,
       round(SUM(DATA_FREE) / 1024 / 1024, 2)                              AS FREE_MB,
       COUNT(*)                                                            AS TABLES
FROM INFORMATION_SCHEMA.tables
WHERE TABLE_SCHEMA NOT IN ('sys', 'mysql', 'INFORMATION_SCHEMA', 'performance_schema')
GROUP BY TABLE_SCHEMA
ORDER BY 2 DESC;

SELECT TABLE_SCHEMA,
       TABLE_NAME,
       round((data_length + index_length + DATA_FREE) / 1024 / 1024, 2) AS TOTAL_MB,
       round(data_length / 1024 / 1024, 2)                              AS DATA_MB,
       round(index_length / 1024 / 1024, 2)                             AS INDEX_MB,
       round(DATA_FREE / 1024 / 1024, 2)                                AS FREE_MB,
       CONCAT(ROUND(DATA_FREE / data_length, 2), ' %')                  AS FREE_PCT
FROM INFORMATION_SCHEMA.tables
WHERE TABLE_SCHEMA = '数据库名'
  and TABLE_NAME = '表名'
ORDER BY TOTAL_MB DESC;

-- 以下 SQL 效果相同
ALTER TABLE tbl_name ENGINE=INNODB;

-- 有审核平台有规范不允许修改存储引擎，可以使用下方 SQL
alter table tbl_name force, ALGORITHM=INPLACE, LOCK=NONE