MySQL是世界上最流行的關系數據庫管理系統之一。作為一款數據庫軟件，MySQL的性能指標至關重要。

MySQL全局性能指標包括以下幾個方面：

1. 配置參數：

mysql>SHOW VARIABLES;
+--------------------------+----------------------------------------------+
| Variable_name            | Value                                        |
+--------------------------+----------------------------------------------+
| auto_increment_increment| 1                                            |
| auto_increment_offset   | 1                                            |
| datadir                  | /var/lib/mysql/                              |
| port                     | 3306                                         |
| slow_query_log_file      | /var/lib/mysql/mysqld-slow.log               |
| log_bin_index            | /var/lib/mysql/mysql-bin.index               |
| max_connections          | 151                                          |
| max_connect_errors       | 100                                          |
| innodb_file_per_table    | ON                                           |
| key_buffer_size          | 8388608                                      |
+--------------------------+----------------------------------------------+

2. 查詢分析：

mysql>EXPLAIN SELECT * FROM user WHERE age >25;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | user  | NULL       | ALL  | NULL          | NULL | NULL    | NULL |    5 |   100.00 | Using where |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+

3. 鎖狀態：

mysql>SHOW ENGINE INNODB STATUS;
..
..
..
---TRANSACTION 78843, ACTIVE 2 sec
2 lock struct(s), heap size 368, 1 row lock(s), undo log entries 1
MySQL thread id 1011, OS thread handle 139717823522560, query id 1640210 localhost root updating
UPDATE user SET age = 28 WHERE name = 'Jack';
-------

4. 慢查詢：

mysql>SHOW VARIABLES LIKE 'slow_query_log%';
+---------------------+--------------------------------------+
| Variable_name       | Value                                |
+---------------------+--------------------------------------+
| slow_query_log      | ON                                   |
| slow_query_log_file | /var/lib/mysql/mysqld-slow.log        |
+---------------------+--------------------------------------+

5. 磁盤IO：

mysql>SHOW GLOBAL STATUS LIKE '%Bytes%';
+----------------------+--------------+
| Variable_name        | Value        |
+----------------------+--------------+
| Bytes_received       | 59291908042  |
| Bytes_sent           | 94277503369  |
| Compressed_bytes_sent| 231594130    |
| Innodb_buffer_pool_bytes_data| 20318720|
| Innodb_buffer_pool_bytes_dirty| 31     |
+----------------------+--------------+

通過以上指標，可實現針對MySQL的性能優化，提升數據庫的處理能力。