This has changed in many cases (though not all): https://dev.mysql.com/doc/refman/5.7/en/innodb-create-index-overview.html https://dev.mysql.com/doc/refman/5.7/

This has changed in many cases (though not all): https://dev.mysql.com/doc/refman/5.7/en/innodb-create-index-overview.html https://dev.mysql.com/doc/refman/5.7/en/innodb-create-index-... There are also a number of tools to work around it for other for other cases: https://githubengineering.com/gh-ost-github-s-online-migration-tool-for-mysql/ https://githubengineering.com/gh-ost-github-s-online-migrati... https://www.percona.com/doc/percona-toolkit/2.1/pt-online-schema-change.html https://www.percona.com/doc/percona-toolkit/2.1/pt-online-sc...