MySQL auto increment ID suddenly jumped to MAXINT, what could be a reason?

Question

I have a mysql table with about 2,000,000 entries, with a primary key which is auto incrementing. However, at one point the auto increment value suddenly jumped from what it

Answer 1

A failed insert can still cause the auto-increment column to increase. If your program went into an infinite loop of failures it could cause the limit to be reached.

It's also possible to set the auto-increment programmatically to a specific value.

ALTER TABLE yourtable AUTO_INCREMENT = 12345;