MySQL除了使用日志对系统进行监视，还可以查看状态变量来监视系统。大部分的变量值以计数器的形式记录发生时间或者事件的数量。系统变量的范围包括全局（GLOBAL）和会话范围（SESSION或LOCAL）默认为会话范围。注意，一些变量仅具有全局范围，无论使用哪个关键字都返回相同的值。
显示状态信息可以通过执行“SHOW STATUS”语句、查询Performance_Schema里面的表，或者使用“mysqladmin”查看。例如，使用“SHOW STATUS”语句，
代码语言：javascript复制 MySQL localhost:3306 ssl SQL > SHOW STATUSG
*************************** 1. row ***************************
Variable_name: Aborted_clients
Value: 0
*************************** 2. row ***************************
Variable_name: Aborted_connects
Value: 1
*************************** 3. row ***************************
Variable_name: Acl_cache_items_count
Value: 0
*************************** 4. row ***************************
Variable_name: Binlog_cache_disk_use
Value: 0
*************************** 5. row ***************************
Variable_name: Binlog_cache_use
Value: 0
......使用performance_schema查看“global_status”或“session_status”，
代码语言：javascript复制MySQL localhost:3306 ssl SQL > SELECT * FROM performance_schema.session_statusG
*************************** 1. row ***************************
VARIABLE_NAME: Aborted_clients
VARIABLE_VALUE: 0
*************************** 2. row ***************************
VARIABLE_NAME: Aborted_connects
VARIABLE_VALUE: 1
*************************** 3. row ***************************
VARIABLE_NAME: Acl_cache_items_count
VARIABLE_VALUE: 0
*************************** 4. row ***************************
VARIABLE_NAME: Binlog_cache_disk_use
VARIABLE_VALUE: 0
*************************** 5. row ***************************
VARIABLE_NAME: Binlog_cache_use
VARIABLE_VALUE: 0
*************************** 6. row ***************************
VARIABLE_NAME: Binlog_stmt_cache_disk_use
VARIABLE_VALUE: 0
*************************** 7. row ***************************
VARIABLE_NAME: Binlog_stmt_cache_use
VARIABLE_VALUE: 0
......除了以上的两个表，还可以查看“status_by_account”，“status_by_host”，“status_by_thread”，“status_by_user”表。
使用“mysqladmin”并通过选项查看状态变量，例如，查看状态信息，
代码语言：javascript复制C:Program FilesMySQLMySQL Server 8.0bin>mysqladmin --user=root -p status
Enter password: ****
Uptime: 1151 Threads: 3 Questions: 13 Slow queries: 0 Opens: 138 Flush tables: 3 Open tables: 57 Queries per second avg: 0.011
查看服务器的变量，及变量值，
代码语言：javascript复制C:Program FilesMySQLMySQL Server 8.0bin>mysqladmin --user=root -p extended-status
Enter password: ****
------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Variable_name | Value
|
------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Aborted_clients | 0
|
| Aborted_connects | 2
|
| Acl_cache_items_count | 0
|
| Binlog_cache_disk_use | 0
|
| Binlog_cache_use | 0
|
| Binlog_stmt_cache_disk_use | 0
......查看服务器的活动线程，
代码语言：javascript复制C:Program FilesMySQLMySQL Server 8.0bin>mysqladmin processlist --verbose --user=root -p
Enter password: ****
---- ----------------- ----------------- ---- --------- ------ ------------------------ -----------------------
| Id | User | Host | db | Command | Time | State | Info |
---- ----------------- ----------------- ---- --------- ------ ------------------------ -----------------------
| 5 | event_scheduler | localhost | | Daemon | 1369 | Waiting on empty queue | |
| 9 | root | localhost:55557 | | Sleep | 1025 | | |
| 14 | root | localhost:55689 | | Query | 0 | init | show full processlist |
---- ----------------- ----------------- ---- --------- ------ ------------------------ ----------------------- 此外，使用“mysqladmin”和选项能够输出非常有效的监视信息，例如，
代码语言：javascript复制C:Program FilesMySQLMySQL Server 8.0bin>mysqladmin extended -i100 --relative --user=root -p可以每100秒显示当前变量值和上一次变量值的不同。
