详细解决The INFORMATION_SCHEMA.xxx feature is disabled； see the documentation for show_compatibility_56

文章目录

1. 复现错误
2. 分析错误
3. 解决问题

1. 复现错误

今天，在使用MySQL查询全局变量时，却报出如下错误：

mysql> select * from information_schema.global_variables;

ERROR 3167 (HY000): The 'INFORMATION_SCHEMA.GLOBAL_VARIABLES' feature is disabled; see the documentation for 'show_compatibility_56'

即The 'INFORMATION_SCHEMA.GLOBAL_VARIABLES' feature is disabled; see the documentation for 'show_compatibility_56'。

同时，使用MySQL查询全局状态时，报出如下同样的错误：

mysql> select * from information_schema.global_status;

ERROR 3167 (HY000): The 'INFORMATION_SCHEMA.GLOBAL_STATUS' feature is disabled; see the documentation for 'show_compatibility_56'

即 The 'INFORMATION_SCHEMA.GLOBAL_STATUS' feature is disabled; see the documentation for 'show_compatibility_56'。

2. 分析错误

将The 'INFORMATION_SCHEMA.GLOBAL_VARIABLES' feature is disabled; see the documentation for 'show_compatibility_56'翻译成中文，便是'INFORMATION_SCHEMA.GLOBAL_VARIABLES“功能已禁用，请参阅“show_compatibility_56”的文档。

同样，INFORMATION_SCHEMA.GLOBAL_STATUS功能也已禁用。

INFORMATION_SCHEMA.GLOBAL_VARIABLES和INFORMATION_SCHEMA.GLOBAL_STATUS，这两个表为什么会被禁用，还要从MySQL的版本说起。

这两个表提供和系统变量相关的信息。

从MySQL 5.7.6开始，这两个表开始被废弃，并将在后续的版本移除，使用如下sql查询我的MySQL版本：

mysql> select version();

```dart
+------------+
| version()  |
+------------+
| 5.7.16-log |
+------------+
1 row in set (0.00 sec)

这个特性通过show_compatibility_56参数控制，同时控制系统变量和状态变量，该参数从5.7.8开始默认为OFF。


我的`MySQL`版本是`5.7.16`，因而，`INFORMATION_SCHEMA.GLOBAL_VARIABLES`和`INFORMATION_SCHEMA.GLOBAL_STATUS` 被禁用(废弃)，但信息可以在`Performance_schema`数据库中查询：

-  `performance_schema.global_variables`

```sql
mysql> select * from performance_schema.global_variables;
+--------------------------+----------------+
| VARIABLE_NAME            | VARIABLE_VALUE |
+--------------------------+----------------+
| auto_increment_increment | 1              |
| auto_increment_offset    | 1              |
| autocommit               | ON             |
| automatic_sp_privileges  | ON             |
| avoid_temporal_upgrade   | OFF            |
| ......                   | ......         |
+--------------------------+----------------+

491 rows in set (0.00 sec)

performance_schema.global_status

mysql> select * from performance_schema.global_status;
+----------------------------+----------------+
| VARIABLE_NAME              | VARIABLE_VALUE |
+----------------------------+----------------+
| Aborted_clients            | 8              |
| Aborted_connects           | 1              |
| Binlog_cache_disk_use      | 0              |
| Binlog_cache_use           | 0              |
| Binlog_stmt_cache_disk_use | 0              |
| ......                     | ......         |
+----------------------------+----------------+
206 rows in set (0.00 sec)

当然，MySQL 5.6之后的系统变量和状态变量，除了使用performance_schema，也可以使用show命令获取：

SHOW VARIABLES ，如下图所示：

在这里插入图片描述

SHOW STATUS，如下图所示：

在这里插入图片描述

SHOW VARIABLES 和SHOW STATUS的数据来源于如下表

INFORMATION_SCHEMA.GLOBAL_VARIABLES
INFORMATION_SCHEMA.SESSION_VARIABLES 
INFORMATION_SCHEMA.GLOBAL_STATUS 
INFORMATION_SCHEMA.SESSION_STATUS

MySQL 5.7.6开始后改成了从如下表获取：

performance_schema.global_variables 
performance_schema.session_variables 
performance_schema.variables_by_thread 
performance_schema.global_status 
performance_schema.session_status 
performance_schema.status_by_thread 
performance_schema.status_by_account 
performance_schema.status_by_host 
performance_schema.status_by_user

从该版本开始MySQL引入了show_compatibility_56参数，来控制show命令从什么地方获取值。

当show_compatibility_56为ON时代表启用了MySQL 5.6的兼容性，这时和MySQL5.6一直

如果show_compatibility_56为OFF，则代表禁用兼容性，这时表的信息通过peformance_schema获取，这时直接查询information_schame会报出如上的错误。

使用如下代码，查看show_compatibility_56，是否关闭：

mysql> show variables like '%show_compatibility_56%';
+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| show_compatibility_56 | OFF   |
+-----------------------+-------+
1 row in set, 1 warning (0.00 sec)

3. 解决问题

可以使用如下方法解决该问题：

使用performance_schema.global_variables和performance_schema.global_status查询系统变量，如上代码所示。

mysql> select * from performance_schema.global_variables where variable_name like '%timeout%';
+-----------------------------+----------------+
| VARIABLE_NAME               | VARIABLE_VALUE |
+-----------------------------+----------------+
| connect_timeout             | 10             |
| delayed_insert_timeout      | 300            |
| have_statement_timeout      | YES            |
| innodb_flush_log_at_timeout | 1              |
| innodb_lock_wait_timeout    | 50             |
| innodb_rollback_on_timeout  | OFF            |
| interactive_timeout         | 28800          |
| lock_wait_timeout           | 31536000       |
| net_read_timeout            | 30             |
| net_write_timeout           | 60             |
| rpl_stop_slave_timeout      | 31536000       |
| slave_net_timeout           | 60             |
| wait_timeout                | 28800          |
+-----------------------------+----------------+
13 rows in set, 1 warning (0.00 sec)

使用show variables和show status查询系统变量

mysql> show variables like '%%timeout';
+-----------------------------+----------+
| Variable_name               | Value    |
+-----------------------------+----------+
| connect_timeout             | 10       |
| delayed_insert_timeout      | 300      |
| have_statement_timeout      | YES      |
| innodb_flush_log_at_timeout | 1        |
| innodb_lock_wait_timeout    | 50       |
| innodb_rollback_on_timeout  | OFF      |
| interactive_timeout         | 28800    |
| lock_wait_timeout           | 31536000 |
| net_read_timeout            | 30       |
| net_write_timeout           | 60       |
| rpl_stop_slave_timeout      | 31536000 |
| slave_net_timeout           | 60       |
| wait_timeout                | 28800    |
+-----------------------------+----------+
13 rows in set, 1 warning (0.00 sec)

将show_compatibility_56设置为on，兼容之前的版本：

mysql> set global show_compatibility_56 = ON;
Query OK, 0 rows affected (0.00 sec)

查询是否设置成功：

mysql> show variables like '%show_compatibility_56%';
+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| show_compatibility_56 | ON    |
+-----------------------+-------+
1 row in set (0.00 sec)

如下，便可以在information_schema.global_variables表中查询数据了：

mysql> select * from information_schema.global_variables where variable_name like '%timeout%' ;
+-----------------------------+----------------+
| VARIABLE_NAME               | VARIABLE_VALUE |
+-----------------------------+----------------+
| INNODB_FLUSH_LOG_AT_TIMEOUT | 1              |
| RPL_STOP_SLAVE_TIMEOUT      | 31536000       |
| INNODB_ROLLBACK_ON_TIMEOUT  | OFF            |
| DELAYED_INSERT_TIMEOUT      | 300            |
| CONNECT_TIMEOUT             | 10             |
| SLAVE_NET_TIMEOUT           | 60             |
| NET_WRITE_TIMEOUT           | 60             |
| INNODB_LOCK_WAIT_TIMEOUT    | 50             |
| LOCK_WAIT_TIMEOUT           | 31536000       |
| HAVE_STATEMENT_TIMEOUT      | YES            |
| NET_READ_TIMEOUT            | 30             |
| INTERACTIVE_TIMEOUT         | 28800          |
| WAIT_TIMEOUT                | 28800          |
+-----------------------------+----------------+
13 rows in set, 1 warning (0.00 sec)