存儲引擎使用InnoDB。

一開始在主庫查詢，一直很好奇為什么索引不生效，切換到備庫之后，發(fā)現(xiàn)備庫是有效的。

開始考慮是不是因為索引出問題，后對索引重建，發(fā)現(xiàn)效率高了不少。

簡單記錄一下對比。

mysql> explain select * from runinfo where status in (0, 2, 1, 3, 4, 7, 9, 10);
+----+-------------+---------+-------+---------------+------+---------+------+----------+-------------+
  id   select_type   table     type    possible_keys   key    key_len   ref    rows       Extra        
+----+-------------+---------+-------+---------------+------+---------+------+----------+-------------+
   1   SIMPLE        runinfo   All     status_2        NULL   NULL      NULL    2378055   Using where  
+----+-------------+---------+-------+---------------+------+---------+------+----------+-------------+
row in set (0.00 sec)

上面是主庫的執(zhí)行計劃。

對比一下備庫的執(zhí)行計劃。

mysql> explain select * from runinfo where status in (0, 2, 1, 3, 4, 7, 9, 10);
+----+-------------+---------+-------+---------------+----------+---------+------+------+-------------+
  id   select_type   table     type    possible_keys   key        key_len   ref    rows   Extra        
+----+-------------+---------+-------+---------------+----------+---------+------+------+-------------+
   1   SIMPLE        runinfo   range   status_2        status_2   4         NULL    116   Using where  
+----+-------------+---------+-------+---------------+----------+---------+------+------+-------------+
row in set (0.00 sec)

可以看出，備庫在查詢時適應(yīng)到索引 status_2。

執(zhí)行如下的命令之后，問題解決。

mysql> OPTIMIZE TABLE runinfo;
+------------------+----------+----------+-------------------------------------------------------------------+
  Table              Op         Msg_type   Msg_text                                                           
+------------------+----------+----------+-------------------------------------------------------------------+
  schedule.runinfo   optimize   note       Table does not support optimize, doing recreate + analyze instead  
  schedule.runinfo   optimize   status     OK                                                                 
+------------------+----------+----------+-------------------------------------------------------------------+
rows in set (47.13 sec)

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