When my service wants to store and retrieve as part of its behaviour, of course I'm going to back it with a hashmap first.
Once I know it fulfills its business logic I'll start fiddling with hard-to-change stuff like DB schemas and migrations.
And having finished and tested the logic, I'll have a much better idea of the actual access patterns so I can design good tables & indexes.
When my service wants to store and retrieve as part of its behaviour, of course I'm going to back it with a hashmap first.
Once I know it fulfills its business logic I'll start fiddling with hard-to-change stuff like DB schemas and migrations.
And having finished and tested the logic, I'll have a much better idea of the actual access patterns so I can design good tables & indexes.