Hi Experts,
I use the following sql, and sink to mysql,
select
album_id, date
count(1)
from
coupon_5_discount_date_conv
group by
album_id, date;
when sink to mysql, the following SQL is executed: insert into xxx
(c1,c2,c3) values (?,?,?) on duplicate key update c1=VALUES(c1),c2=VALUES(c2),
c3=VALUES(c3)
The engine is InnoDB, column c1,c2 is unique key, the isolation level
is READ COMMITTED. But in the log a deadlock exception happens.
As I know, because the unique key exists, only the line lock will be
applied, no gap lock will be applied. And due to a group by sentence, the same
unique key should be written by the same thread. So in this case, why the dead
lock should happened? Could anyone help me? Thanks a lot.
Best
Henry
