MySQL 中常用有效检测数据库运行状态SQL脚本

1、查看数据库中不为 InnoDB 引擎的表

SELECT TABLE_SCHEMA, TABLE_NAME, ENGINE
  FROM information_schema.TABLES
 WHERE TABLE_SCHEMA NOT IN
      ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
   AND ENGINE != 'InnoDB';

2、查看数据库中表的大小及数据量

SELECT TABLE_SCHEMA, TABLE_NAME, TABLE_ROWS,
       CONCAT(round((DATA_LENGTH + INDEX_LENGTH) / 1024 / 1024, 2), 'MB') as data
  FROM information_schema.TABLES
 WHERE TABLE_SCHEMA NOT IN 
       ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
 ORDER BY DATA_LENGTH + INDEX_LENGTH DESC;

3、查找数据库中无显式主键索引的表

SELECT t.TABLE_SCHEMA, t.TABLE_NAME
  FROM information_schema.TABLES t
 WHERE (t.TABLE_SCHEMA, t.TABLE_NAME) NOT IN
       (SELECT DISTINCT TABLE_SCHEMA, TABLE_NAME
          FROM information_schema.COLUMNS
         WHERE COLUMN_KEY = 'PRI')
   AND t.TABLE_SCHEMA NOT IN
       ('sys', 'mysql', 'performance_schema', 'information_schema', 'test');

4、查找数据库中主键为联合主键的表

SELECT TABLE_SCHEMA, TABLE_NAME,
       GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX SEPARATOR ',') cols,
       MAX(SEQ_IN_INDEX) len
  FROM information_schema.STATISTICS
 WHERE INDEX_NAME = 'PRIMARY'
   AND TABLE_SCHEMA NOT IN
       ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
 GROUP BY TABLE_SCHEMA, TABLE_NAME
HAVING len > 1;

5、查找数据库中不为自增主键的表

SELECT TABLE_SCHEMA, TABLE_NAME
  FROM information_schema.TABLES
 WHERE TABLE_SCHEMA NOT IN ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
   AND (TABLE_SCHEMA,TABLE_NAME) NOT IN 
       (SELECT TABLE_SCHEMA, TABLE_NAME
          FROM information_schema.COLUMNS
         WHERE TABLE_SCHEMA NOT IN ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
           AND IS_NULLABLE = 'NO'
           AND COLUMN_TYPE LIKE '%int%'
           AND COLUMN_KEY = 'PRI'
           AND EXTRA = 'auto_increment');

6、查看数据库中存在外键约束的表

SELECT c.TABLE_SCHEMA,
       c.REFERENCED_TABLE_NAME,
       c.REFERENCED_COLUMN_NAME,
       c.TABLE_NAME,
       c.COLUMN_NAME,
       c.CONSTRAINT_NAME,
       t.TABLE_COMMENT,
       r.UPDATE_RULE,
       r.DELETE_RULE
  FROM information_schema.KEY_COLUMN_USAGE c
  JOIN information_schema.TABLES t
    ON t.TABLE_NAME = c.TABLE_NAME
  JOIN information_schema.REFERENTIAL_CONSTRAINTS r
    ON r.TABLE_NAME = c.TABLE_NAME
   AND r.CONSTRAINT_NAME = c.CONSTRAINT_NAME
   AND r.REFERENCED_TABLE_NAME = c.REFERENCED_TABLE_NAME
 WHERE c.REFERENCED_TABLE_NAME IS NOT NULL;

7、查找数据库中低区分度索引（区分度小于0.1）

SELECT p.TABLE_SCHEMA, p.TABLE_NAME, c.INDEX_NAME, c.car, p.car total
  FROM (SELECT TABLE_SCHEMA, TABLE_NAME, INDEX_NAME, MAX(CARDINALITY) car
          FROM information_schema.STATISTICS
         WHERE INDEX_NAME != 'PRIMARY'
           AND TABLE_SCHEMA NOT IN  ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
         GROUP BY TABLE_SCHEMA, TABLE_NAME, INDEX_NAME) c
 INNER JOIN (SELECT TABLE_SCHEMA, TABLE_NAME, MAX(CARDINALITY) car
               from information_schema.STATISTICS
              WHERE INDEX_NAME = 'PRIMARY'
                AND TABLE_SCHEMA NOT IN  ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
              GROUP BY TABLE_SCHEMA, TABLE_NAME) p
    ON c.TABLE_NAME = p.TABLE_NAME
   AND c.TABLE_SCHEMA = p.TABLE_SCHEMA
 WHERE p.car > 0
   AND c.car / p.car < 0.1;

8、查找数据库中重复索引前缀的索引

 SELECT a.TABLE_SCHEMA, a.TABLE_NAME, a.INDEX_NAME, a.cols, b.INDEX_NAME, b.cols
  FROM (SELECT TABLE_SCHEMA, TABLE_NAME, INDEX_NAME,
               CONCAT('| ', GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX SEPARATOR ' | '), ' |') AS cols
          FROM information_schema.STATISTICS
         WHERE TABLE_SCHEMA NOT IN  ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
           AND INDEX_NAME != 'PRIMARY'
         GROUP BY TABLE_SCHEMA, TABLE_NAME, INDEX_NAME) a
 INNER JOIN (SELECT TABLE_SCHEMA, TABLE_NAME, INDEX_NAME,
                    CONCAT('| ', GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX SEPARATOR ' | '), ' |') AS cols
               FROM information_schema.STATISTICS
              WHERE TABLE_SCHEMA NOT IN  ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
                AND INDEX_NAME != 'PRIMARY'
              GROUP BY TABLE_SCHEMA, TABLE_NAME, INDEX_NAME) b
    ON a.TABLE_NAME = b.TABLE_NAME
   AND a.TABLE_SCHEMA = b.TABLE_SCHEMA
   AND a.cols LIKE CONCAT(b.cols, '%')
   AND a.INDEX_NAME != b.INDEX_NAME;

9、查找数据库中包索引重复包含主键列的索引

SELECT a.*, b.pk
  FROM (SELECT TABLE_SCHEMA, TABLE_NAME, INDEX_NAME,
               CONCAT('| ', GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX SEPARATOR ' | '), ' |') cols
          FROM information_schema.STATISTICS
         WHERE INDEX_NAME != 'PRIMARY'
           AND TABLE_SCHEMA NOT IN  ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
         GROUP BY TABLE_SCHEMA, TABLE_NAME, INDEX_NAME) a
 INNER JOIN (SELECT TABLE_SCHEMA, TABLE_NAME,
                    CONCAT('| ', GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX SEPARATOR ' | '), ' |') pk
               FROM information_schema.STATISTICS
              WHERE INDEX_NAME = 'PRIMARY'
                AND TABLE_SCHEMA NOT IN  ('sys', 'mysql', 'performance_schema', 'information_schema', 'test')
              GROUP BY TABLE_SCHEMA, TABLE_NAME) b
    ON a.TABLE_NAME = b.TABLE_NAME
   AND a.TABLE_SCHEMA = b.TABLE_SCHEMA
   AND a.cols LIKE CONCAT('%', b.pk, '%');

10、查找数据库中没有被使用的索引

SELECT a.OBJECT_SCHEMA, a.OBJECT_NAME, a.INDEX_NAME, b.TABLE_ROWS
  FROM performance_schema.TABLE_IO_WAITS_SUMMARY_BY_INDEX_USAGE a
 INNER JOIN information_schema.TABLES b
    ON a.OBJECT_SCHEMA = b.TABLE_SCHEMA
   AND a.OBJECT_NAME = b.TABLE_SCHEMA
 WHERE a.INDEX_NAME IS NOT NULL
   AND a.INDEX_NAME != 'PRIMARY'
   AND a.COUNT_STAR = 0
   AND OBJECT_SCHEMA NOT IN
       ('sys', 'mysql', 'performance_schema', 'information_schema')
 ORDER BY OBJECT_SCHEMA, OBJECT_NAME;

11、查看数据库中的锁请求信息

SELECT r.TRX_ISOLATION_LEVEL,
       r.TRX_ID                              WAITING_TRX_ID,
       r.TRX_MYSQL_THREAD_ID  WAITING_TRX_THREAD,
       r.TRX_STATE                       WAITING_TRX_STATE,
       lr.LOCK_MODE                    WAITING_TRX_LOCK_MODE,
       lr.LOCK_TYPE                     WAITING_TRX_LOCK_TYPE,
       lr.LOCK_TABLE                   WAITING_TRX_LOCK_TABLE,
       lr.LOCK_INDEX                    WAITING_TRX_LOCK_INDEX,
       r.TRX_QUERY                      WAITING_TRX_QUERY,
       b.TRX_ID                              BLOCKING_TRX_ID,
       b.TRX_MYSQL_THREAD_ID  BLOCKING_TRX_THREAD,
       b.TRX_STATE                       BLOCKING_TRX_STATE,
       lb.LOCK_MODE                    BLOCKING_TRX_LOCK_MODE,
       lb.LOCK_TYPE                     BLOCKING_TRX_LOCK_TYPE,
       lb.LOCK_TABLE                   BLOCKING_TRX_LOCK_TABLE,
       lb.LOCK_INDEX                    BLOCKING_TRX_LOCK_INDEX,
       b.TRX_QUERY                     BLOCKING_QUERY
  FROM information_schema.INNODB_LOCK_WAITS w
 INNER JOIN INFORMATION_SCHEMA.INNODB_TRX b
    ON b.TRX_ID = W.BLOCKING_TRX_ID
 INNER JOIN information_schema.INNODB_TRX R
    ON r.TRX_ID = W.REQUESTING_TRX_ID
 INNER JOIN information_schema.INNODB_LOCKS lb
    ON lb.LOCK_TRX_ID = W.BLOCKING_TRX_ID
 INNER JOIN information_schema.INNODB_LOCKS lr
    ON lr.LOCK_TRX_ID = W.REQUESTING_TRX_ID;

注：本文提供的 SQL 脚本只适应特定的数据库版本，不代表所有数据库版本。