https://www.indiehackers.com/ is a great source for this sort of question. They provide various filtering mechanisms as well such as revenue, number of employees, business model, location, etc.
Tools such as the percona toolkit (https://www.percona.com/software/mysql-tools/percona-toolkit) provide the ability to perform safe and performant online alters for MySQL. Behind the scenes it actually creates a new table with the new schema and utilizes triggers to apply writes to the new table as the original data is being copied. Once it completes the table is renamed and the triggers are removed.
Percona also recommends using this tool to safely perform alters for any Galera-based replication product (Percona XtraDB Cluster, MariaDB Galera Cluster, etc.)