Re: Select for update twice to same table by diffrenet key cause deadlock

[kouhei toki]

I figured out close answer.

MySQL locks all records when select for update searched by no indexed column.

>> quote from MySQL manual
https://dev.mysql.com/doc/refman/5.7/en/innodb-locks-set.html

If you have no indexes suitable for your statement and MySQL must scan the entire table to process the statement, every row of the table becomes locked, which in turn blocks all inserts by other users to the table.
<<

But, I don't know why this causes deadlock.

By the way, I resolved my problem that every select for update to search by primary key.