I'm assuming you mean in production micro-service, if that's not the case, please elaborate a bit more...

The short answer is "no," as succinctly stated by the, I assume from the name, majestic SideburnsOfDoom. The versions shouldn't _EVER_ be incompatible with each other.

E.g. you need to rename a column.

Do not: rename the column, e.g. `ALTER TABLE RENAME COLUMN...`. Because, your systems are going to break with the new schema.

Do: Add a new column, with the new name, and migrate data to the new column, once it's good upgrade the rest of your instances, then drop the old column. Because, you can use both versions at the same time now without breaking anything. Yes, it can be a little tricky to get the data sync'd into the new column, but that's a lot less tricky than doing it for _every_ table and column.

Those are just different (versions of) interfaces for interacting with the same data source, ie no not several databases... But I'm no expert

No.