MySQL的自聯接僵局

Question

我有以下查詢：

UPDATE messages QM JOIN (SELECT id FROM messages WHERE name = 'name' 
AND state = 0 ORDER BY priority DESC, timestamp DESC LIMIT 1) AS QM2 
ON QM.name ='name' AND QM.id = QM2.id SET QM.weight = QM.weight + 1; 

（我需要在這裏自連接因爲MySQL無法使用索引的ORDER BY與簡單的更新）

還有就是綜合指數在(name, state, priority, timestamp)列。它完美匹配上面的查詢。

我的問題是一個巨大的死鎖的量時，查詢率> 80個RPS：

------------------------ 
LATEST DETECTED DEADLOCK 
------------------------ 
2017-05-15 12:04:49 7f7992119b00 
*** (1) TRANSACTION: 
TRANSACTION 3923289, ACTIVE 0 sec starting index read 
mysql tables in use 2, locked 2 
LOCK WAIT 4 lock struct(s), heap size 1184, 4 row lock(s) 
MySQL thread id 992, OS thread handle 0x7f7958b5eb00, query id 1325283 172.17.0.1 facade Sending data 
UPDATE queue_messages m1 JOIN 
     (SELECT id FROM queue_messages WHERE queue_name = ? AND state = 0 ORDER BY priority DESC, message_timestamp DESC LIMIT ?) 
      AS m2 ON m1.queue_name = ? AND m1.id = m2.id SET m1.state = 1, m1.transient_token = ?, m1.transient_token_expiration_timestamp = ?, m1.retry_count = retry_count + 1 
*** (1) WAITING FOR THIS LOCK TO BE GRANTED: 
RECORD LOCKS space id 1772 page no 2464 n bits 304 index `QUEUE_NAME_STATE_PRIORITY_MESSAGE_TIMESTAMP_INDEX` of table `actionmq_data`.`queue_messages` trx table locks 1 total table locks 4 trx id 3923289 lock mode S waiting lock hold time 0 wait time before grant 0 

*** (2) TRANSACTION: 
TRANSACTION 3923243, ACTIVE 0 sec updating or deleting 
mysql tables in use 2, locked 2 
9 lock struct(s), heap size 2936, 9 row lock(s), undo log entries 1 
MySQL thread id 975, OS thread handle 0x7f7992119b00, query id 1325044 172.17.0.1 facade updating reference tables 
UPDATE queue_messages m1 JOIN 
     (SELECT id FROM queue_messages WHERE queue_name = ? AND state = 0 ORDER BY priority DESC, message_timestamp DESC LIMIT ?) 
      AS m2 ON m1.queue_name = ? AND m1.id = m2.id SET m1.state = 1, m1.transient_token = ?, m1.transient_token_expiration_timestamp = ?, m1.retry_count = retry_count + 1 
*** (2) HOLDS THE LOCK(S): 
RECORD LOCKS space id 1772 page no 2464 n bits 304 index `QUEUE_NAME_STATE_PRIORITY_MESSAGE_TIMESTAMP_INDEX` of table `actionmq_data`.`queue_messages` trx table locks 2 total table locks 4 trx id 3923243 lock_mode X locks rec but not gap lock hold time 0 wait time before grant 0 
*** (2) WAITING FOR THIS LOCK TO BE GRANTED: 
RECORD LOCKS space id 1772 page no 2469 n bits 168 index `QUEUE_NAME_STATE_PRIORITY_MESSAGE_TIMESTAMP_INDEX` of table `actionmq_data`.`queue_messages` trx table locks 2 total table locks 4 trx id 3923243 lock_mode X locks gap before rec insert intention waiting lock hold time 0 wait time before grant 0 
*** WE ROLL BACK TRANSACTION (1) 

我該如何解決呢？

Answer 1

你可以試試這個：

UPDATE messages QM SET QM.weight = (QM.weight + 1) WHERE QM.id = (SELECT id FROM messages WHERE name = 'name' AND state = 0 ORDER BY priority DESC, timestamp DESC LIMIT 1) 

Answer 2

如果id是PRIMARY KEY，然後加入上name是多餘的：

ON QM.name ='name' AND QM.id = QM2.id 

見，如果這個工程沒有更好：

BEGIN; 
SELECT @id := id 
    FROM messages 
    WHERE name = 'name' 
     AND state = 0 
    ORDER BY priority DESC, timestamp DESC 
    LIMIT 1 
    FOR UPDATE; 
UPDATE messages 
    SET weight = weight + 1 
    WHERE id = @id; 
COMMIT; 

或者

UPDATE messages 
    SET weight = weight + 1 
    WHERE id = (SELECT id 
        FROM messages 
        WHERE name = 'name' 
        AND state = 0 
        ORDER BY priority DESC, timestamp DESC 
        LIMIT 1 
       ); 

或者乾脆

UPDATE messages 
    SET weight = weight + 1 
    WHERE name = 'name' 
     AND state = 0 
    ORDER BY priority DESC, timestamp DESC 
    LIMIT 1;