> Are microservices meant to separate data too? As in, each service has its own database.
Yes.
> Wouldn't that lead to non-normalisation of the data
Yes. But it's not as bad as it sounds. That is how data on paper used to work, after all.
Business rules (at least ones that have been around for more than 5--10 years) are written with intensely non-normalised data in mind.
Business people tend to be fine with eventual consistency on the scale of hours or even days.
Non-normalised data also makes total data corruption harder, and forensics in the case of bugs easier, in some ways: you find an unexpected value somewhere? Check the other versions that ought to exist and you can probably retrace at what point it got weird.
The whole idea of consistent and fully normalised data is a, historically speaking, very recent innovation, and I'm not convinced it will last long in the real world. I think this is a brief moment in history when our software is primitive enough, yet optimistic enough, to even consider that type of data storage.
And come on, it's not like the complete consistency of the data is worth that many dollars in most cases, if we actually bother to compute the cost.
Yes.
> Wouldn't that lead to non-normalisation of the data
Yes. But it's not as bad as it sounds. That is how data on paper used to work, after all.
Business rules (at least ones that have been around for more than 5--10 years) are written with intensely non-normalised data in mind.
Business people tend to be fine with eventual consistency on the scale of hours or even days.
Non-normalised data also makes total data corruption harder, and forensics in the case of bugs easier, in some ways: you find an unexpected value somewhere? Check the other versions that ought to exist and you can probably retrace at what point it got weird.
The whole idea of consistent and fully normalised data is a, historically speaking, very recent innovation, and I'm not convinced it will last long in the real world. I think this is a brief moment in history when our software is primitive enough, yet optimistic enough, to even consider that type of data storage.
And come on, it's not like the complete consistency of the data is worth that many dollars in most cases, if we actually bother to compute the cost.