What Should I Do If a MySQL Auto-Increment Primary Key Reaches the Maximum Value?

If an auto-increment primary key in MySQL reaches the maximum value of its data type, new insertions will fail.

You can handle the issue as follows:

• Check primary key values and check whether the value of the auto-increment primary key approaches the maximum allowed.
  • If yes, perform either of the following operations:
    • Change the data type to a larger integer, for example, change from INT to BIGINT.
    • Change the primary key. If you do not want to change the data type of the primary key, use either of the following methods:
      1. Reallocate primary key values.

         Delete some unnecessary records or reallocate primary key values. If you choose this method, you must back up data, reset primary key values, and then insert data.

      2. Use a composite primary key.

         If a single auto-increment primary key cannot meet your needs, consider using a composite primary key.

  • If no, submit a service ticket.
• Shard data.

  If the value of an auto-increment primary key in a single table frequently approaches the maximum allowed, shard the data into multiple tables. Each table can have its own auto-increment primary key, thereby extending the usage of primary keys.

• Use UUIDs.

  If auto-increment primary keys no longer meet your needs, consider using UUIDs as primary keys. While this may increase storage space and index complexity, it can prevent the issue that auto-increment primary keys reach their maximum values.

• Regularly monitor the values of auto-increment primary keys.

  Regularly monitor the values of auto-increment primary keys to proactively identify and handle issues. You can set an alarm to alert you when an auto-increment primary key approaches its maximum value.

• Adjust the auto-increment step and offset.

  Although adjusting the auto-increment step and offset cannot solve this issue, it can reduce conflicts and improve performance in some cases.

• Use external unique identifiers.

  Use unique identifiers generated by an application, instead of relying on auto-increment primary keys of databases. For example, use the Snowflake algorithm to generate globally unique IDs.

These methods can effectively handle and prevent the issue of auto-increment keys reaching their maximum values in MySQL. Choose one if needed.