[newhouseb]

This is true, but note that the article was written in the context of PostgreSQL instead of MySQL. PostgreSQL can do many types of table migrations with no downtime (dropping columns, renaming, adding columns that default to NULL, and creating indexes). Before I made the switch from MySQL to Postgres I did some quick benchmarks which support these claims on a 5 million row test table: https://gist.github.com/1620133.

[morganpyne]

Guilty as charged for immediately assuming that the problems of the MySQL family apply to other databases. Thank you for pointing out that PostgreSQL does not necessarily have all the same limitations.