[英]MySQL - Multi-threaded Update (no thread updates the same id) but having Deadlock
I have a multi threaded java program that is running update statements on my MySQL DB. 我有一个多线程Java程序,正在我的MySQL DB上运行更新语句。 When I use threads I get deadlock although I am never updating the same rows in any two threads. 当我使用线程时,尽管我从未在任何两个线程中更新相同的行,但会出现死锁。 For each time this query is ran field_a is different so why would I have lock issues? 对于每次运行此查询,field_a都不相同,所以为什么会有锁问题?
thread1: field_a - 'A'
thread2: field_a - 'B'
thread3: field_a - 'C'
I am running a query like this 我正在运行这样的查询
UPDATE table as t,
(
SELECT field_a,
field_b,
TRUNCATE(AVG(Sumfield_c), 2) avgfield_c,
TRUNCATE(AVG(Sumfield_d), 2) avgfield_d
FROM
(SELECT field_a,
field_b,
DateString,
sum(field_c) Sumfield_c,
sum(field_d) Sumfield_d
FROM table
WHERE DateString > DATE_FORMAT(SUBDATE(CURDATE(), 22), '%Y%m%d') and field_a = ? and id <= ?
GROUP BY field_a,
field_b,
DateString) A
GROUP BY field_a,
field_b
) as temp
SET t.Avgfield_c = temp.avgfield_c, t.Avgfield_d = temp.avgfield_d WHERE t.field_a = temp.field_a and t.field_b = temp.field_b and t.id > ?;
After hours and hours I got it working by creating a new index. 几个小时后,我通过创建新索引使其工作。
CREATE INDEX newIndex ON table (fieldA, fieldB); CREATE INDEX newIndex ON表(fieldA,fieldB);
Hope this helps someone in the future running a similar query with threading. 希望这有助于将来使用线程运行类似查询的人。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.