Cosmos: Add API to map every entity type hierarchy to a separate container

[JoshTango]

You released an article today which said this "our prototype mapped entities in each inheritance hierarchy to their own separate Cosmos DB collections, but because of the way Cosmos DB pricing works, this could become unnecessarily expensive" and as a result you used a discriminator and pushed all entities into one collection.
The thing is thought that Azure changed its pricing to allow you to configure your RTU's globally for all collections and not by single collections.
So maybe you might want to offer an option instead. It seems you made a design decision based on Azures poor decision to do pricing per collection but now that they fixed that you should fix yours to. This is yet another example of Azures bad pricing model that lead to poor design decisions.

[divega]

@JoshTango thanks for bringing this up. I agree that ignoring the pricing, having each aggregate map to a separate collection is more natural. We definitively plan to provide an option for that.

We talked to the Cosmos DB team about the new global pricing model before we decided, and with the data we had at the time, mapping to a single collection seemed to be a better default anyway.

We will follow up to see if there is any new data that may help us change the decision.

[cwe1ss]

They have not really fixed their pricing. The minimum RUs for the new database provisioning is 50.000 RU/s which is ~ 300 USD / month. That's still very expensive for dev environments and smaller projects.

[JoshTango]

that's not what I meant, what I meant was they used to have RU's per collection, now they have an option to have RU's applied globally to all the collections.

[divega]

These are two options you choose from: per database or per collection reserved throughput. The per database option was added more recently. See https://azure.microsoft.com/pricing/details/cosmos-db/.

Anyway, as I said, we will follow up to see if we should change the default.

[cwe1ss]

My previous calculation was wrong. 50K RU/s cost almost 3000 USD / month. They've just reduced the minimum DB RU/s to 10K though - which still costs 585 USD / month - and still is out of reach for many scenarios.

[ajcvickers]

Switch the default.