Online schema changes (and upgrades) are absolutely critical for high-availability applications. In cockroachdb all schema changes are online and work more or l

Online schema changes (and upgrades) are absolutely critical for high-availability applications. In cockroachdb all schema changes are online and work more or less like this. One thing you give up with more or less all of these things is the ability to perform the migrations in a transaction. Postgres is quite advanced relative to other databases in terms of its ability to perform DDLs in transactions. Cockroach still isn't there either -- though it's making real progress, at least in terms of transactions that exclusively consist of DDLs (i.e. don't mix DDLs with DMLs).