No-downtime upgrades

[lortabac]

Is it possible to upgrade Hydra with zero downtime?
In particular, can a new version run safely on a database that hasn't been migrated yet? Or vice versa, can an old version run on a database that is on a more recent version (within a reasonable distance)?

[vinckr]

can a new version run safely on a database that hasn't been migrated yet?

I never tried this out but my understanding is that you need to run hydra-migrate-sql before.
Is that correct or can you add something regarding no-downtime upgrading @grantzvolsky ?

[grantzvolsky]

It is generally not possible to upgrade hydra with zero downtime. See #1236 (comment)