Upgrading a Scalingo for MySQL® database from MySQL® 8.0.x LTS to MySQL® 8.4.x LTS may be refused if your schema uses features that are no longer supported in MySQL® 8.4.

This page lists the only upgrade blockers you can address from your side on Scalingo. If you need a broader overview of changes between MySQL 8.0 and 8.4, refer to Oracle’s upgrade notes.

Checking AUTO_INCREMENT on FLOAT or DOUBLE

MySQL® 8.4 no longer supports AUTO_INCREMENT on FLOAT and DOUBLE columns. If your schema contains such a column, Scalingo will refuse the upgrade.

You can list the impacted columns with the following SQL statement:

SELECT table_schema, table_name, column_name
		 FROM information_schema.columns
		 WHERE extra LIKE '%%auto_increment%%'
		   AND data_type IN ('float', 'double')

If the query returns rows, you must remove AUTO_INCREMENT from these columns and use a supported identifier pattern, for example an integer primary key.

Checking Prefix Columns in Partitioning Keys

MySQL® 8.4 no longer allows prefix columns in partitioning keys. This pattern was deprecated in MySQL® 8.0 and is now rejected.

You first need to list partitioned tables:

SELECT DISTINCT
    p.TABLE_SCHEMA,
    p.TABLE_NAME,
    s.COLUMN_NAME,
    s.SUB_PART
FROM information_schema.PARTITIONS p
JOIN information_schema.STATISTICS s
    ON s.TABLE_SCHEMA = p.TABLE_SCHEMA
   AND s.TABLE_NAME = p.TABLE_NAME
WHERE
    p.PARTITION_NAME IS NOT NULL
    AND p.PARTITION_METHOD IN ('KEY', 'LINEAR KEY')
    AND s.NON_UNIQUE = 0
    AND s.SUB_PART IS NOT NULL
    AND (
        INSTR(p.PARTITION_EXPRESSION, CONCAT('`', s.COLUMN_NAME, '`')) > 0
        OR p.PARTITION_EXPRESSION IS NULL
    ); 

If the query returns rows, your database contains partitioned tables. You must review their partitioning definitions and ensure no partitioning key uses a prefix length before you can upgrade to MySQL® 8.4.

For each table returned by the query above, inspect the partitioning definition:

SHOW CREATE TABLE `foo`;

If you find a partitioning key using a prefix length, you need to update the table definition to remove this pattern.

If you fixed all the issues listed above, or if none were detected, you can now safely perform the upgrade from the Scalingo dashboard.