Differences Between Auto-incrementing primary keys of mysql Storage types and primary keys of mysql Storage

Differences Between Auto-incrementing primary keys of mysql Storage types and primary keys of mysql Storage

Q: if there is a table with an auto-increment primary key whose field is id, after 10 data entries have been inserted into the table, the data with id and 10 has been deleted, restart mysql and insert a data record. What is the id of the data record, which is 8 or 11?
A: If the table type is MyISAM, it is 11. If the table type is InnoDB, the id is 8.
This is because the two types of storage engines store the maximum ID records in different ways, MyISAM table records the maximum ID to the data file, the maximum ID value of the auto-incrementing primary key of mysql is not lost;
While InnoDB records the maximum ID value to the memory. Therefore, after you restart mysql or OPTIMIZE the table, the maximum ID value will be lost.