MySQL slow_log表不能修改成innodb引擎

背景

從mysql.slow_log 獲取慢查詢日誌很慢，該表是csv表，沒有索引。
想添加索引來加速訪問，而csv引擎不能添加索引（csv引擎存儲是以逗號分割的文本來存儲的），只能改存儲引擎來添加索引了

mysql.slow_log表能改成myisam，不能改成innodb

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

mysql> alter table  mysql.slow_log engine=innodb;
ERROR 1579 (HY000): This storage engine cannot be used for log tables"
mysql> alter table  mysql.slow_log engine=myisam;
Query OK, 33760 rows affected (0.37 sec)
Records: 33760  Duplicates: 0  Warnings: 0

mysql.general_log也不能改成innodb

mysql> alter table  mysql.general_log engine=myisam;
Query OK, 242956 rows affected (2.41 sec)
Records: 242956  Duplicates: 0  Warnings: 0

mysql> alter table  mysql.general_log engine=innodb;
ERROR 1579 (HY000): This storage engine cannot be used for log tables"

官方文檔