ALGORITHM=INSTANT on Aurora: Which ALTER TABLE Operations Are Truly Zero-Downtime

In a high-availability Aurora MySQL environment, minimizing downtime during schema changes is paramount. Traditional ALTER TABLE operations often require table locks, blocking reads and writes for the duration of the operation. This is unacceptable for applications with stringent uptime requirements. ALGORITHM=INSTANT was introduced to address this by performing certain ALTER TABLE operations without taking a metadata lock for the entire duration. Instead, it applies the change to the table's me