This isn't the kind of thing anyone can answer without a real world scenario. An abstract problem like a counter may or may not need to be in the DB, and just b

This isn't the kind of thing anyone can answer without a real world scenario. An abstract problem like a counter may or may not need to be in the DB, and just because you have a DB doesn't mean you should rely on it for locking or atomicity (maybe you have a read replica and your writes/reads are happening in different places, maybe the data is only useful temporarily and if the service dies it doesn't matter that it's lost, etc.)