MySQL DB_ROW_ID with a table having BIGINT

Question

MySQL has an internal column per row, 6 byte DB_ROW_ID. How does MySQL generate this ID for a table that has (2^64)-1 rows in it without duplicating DB_ROW_ID?

Answer 1

The internal 6-byte id for InnoDB exists only if you don't have either

• An explicit PRIMARY KEY, or
• A UNIQUE with non-null column(s).

Anyway, there are multiple hard limits that will be hit before a table reaches (2^64)-1 rows. Some will be hit before 2^48.

More on limits: http://mysql.rjweb.org/doc.php/limits