變數檢視與設定
mysql> show variables\G;
mysql> show variables like "變數名";
mysql> set global 變數名=值;
檢視最大連線數
mysql> show variables like "max_connections";
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 151 |
+-----------------+-------+
設定最大連線數
mysql> set global max_connections=1000;
重新整理連線數
mysql> flush status;
檢視連線超時
mysql> show variables like "connect_timeout";
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| connect_timeout | 10 |
+-----------------+-------+
設定連線超時
mysql> set global connect_timeout=5;
檢視執行緒狀態
mysql> show status like "Threads%";
+-------------------+-------+
| Variable_name | Value |
+-------------------+-------+
| Threads_cached | 1 |
| Threads_connected | 1 |
| Threads_created | 2 |
| Threads_running | 1 |
+-------------------+-------+
檢視連線程序
mysql> show processlist;
+----+------+-----------+------+---------+------+----------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+------+---------+------+----------+------------------+
| 8 | root | localhost | NULL | Query | 0 | starting | show processlist |
+----+------+-----------+------+---------+------+----------+------------------+
檢視快取執行緒數量
mysql> show variables like "thread_cache_size";
+-------------------+-------+
| Variable_name | Value |
+-------------------+-------+
| thread_cache_size | 9 |
+-------------------+-------+
檢視執行緒緩衝開啟表的數量
mysql> show variables like "table_open_cache";
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| table_open_cache | 2000 |
+------------------+-------+
檢視用於MyISAM引擎的關鍵索引快取大小
mysql> show variables like "key_buffer_size";
+-----------------+---------+
| Variable_name | Value |
+-----------------+---------+
| key_buffer_size | 8388608 |
+-----------------+---------+
檢視查詢快取的一些引數
mysql> show variables like "%query_cache%";
+------------------------------+---------+
| Variable_name | Value |
+------------------------------+---------+
| have_query_cache | YES |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 1048576 |
| query_cache_type | OFF |
| query_cache_wlock_invalidate | OFF |
+------------------------------+---------+

其他日誌引數設定
錯誤日誌
log_error[=檔名] //不指定為預設檔名
查詢日誌
general_log //啟用日誌
general_log-file=檔名 //不指定為預設檔名
慢查詢日誌
slow_query_log //啟用日誌
slow_query_log_file=檔名 //不指定為預設檔名
long-query_time=超時時間 //指定超時時間預設為10秒
log_queries_not_using_indexes=1 //記錄未使用索引的sql查詢