There are other options for zero downtime schema changes in MySQL and MariaDB. You can use the database's built-in support for instant DDL (algorithm=instant)

There are other options for zero downtime schema changes in MySQL and MariaDB. You can use the database's built-in support for instant DDL (algorithm=instant) for adding and dropping columns. And then use Percona's pt-online-schema-change for all other cases, since it supports foreign keys. Or if you're using a physical replication setup -- for example AWS Aurora without any traditional binlog replicas -- you can get away with using the database's built-in "online DDL" (algorithm=inplace, lock=none) for quite a few other cases. Historically the main problem with that method is that it causes replication lag, but that's a non-issue if you're not using logical replication in the first place. So then you only need to fall back to pt-osc for the rarer ALTER cases which don't support online DDL. MariaDB 10.8+ also has an option called binlog_alter_two_phase, which can allow you to use online DDL without causing much replication lag.