Comment by Macha

1. No transactional DDL

2. No MERGE statement

3. No partial indices

4. Many ways to lock out instant add table, meaning you can’t add a column without a full table write, which can lock the table for minutes at a time in even moderately sized tables.

5. Dealing with legacy mysql databases often means dealing with utf8mb3, which used to be the default utf8 data type despite not storing all utf8

6. Dealing with all but the most recent mysql databases means dealing with non strict mode which means your NOT NULL column won’t require a value.