I wish there were some actual stories here about tricky migrations and how they were handled, rather than defaulting to the naturally turf war framing here.

If my experience, writing code that is “future migration friendly” is one of the hallmarks of senior developer knowledge. It’s just the kind of thing that burrows into your brain, because most senior devs have seen, built, or maintained code with randomly cordoned off “WARNING NONSENSICAL THING HERE” style sections of massive codebases that are artifacts of various migration things.

For context about how we do it, we use a giant NoSQL single table design, with zero joins. All joining is handled in the application, which ends up forcing everyone to consider how to parallelize and lookahead rather than join. Additionally, any complex data is stored as row level binary blobs from a versioned schema, which also helps localize issues to a particular subtype rather than leaking it into all schemas (for example if you change what qualifies as an “update”, your “updatedAt” column doesn’t suddenly change meanings for all things.