What are your requirements? And… any reason why you wouldn’t want to use Postgres?

_Also did you see the MongoDB adapters here: Packages | Hex

We were having systems running on MySQL previously and chose mongo due to scalability issues. And postgres doesn’t natively provide sharding. I think postgres is more suited for read-heavy workloads. Our workloads are more write-heavy, so we chose Mongo.

I checked the adapters for mongo and most of them aren’t maintained anymore.

Also from the author of the package:

What features are you looking for from a mongo driver? There has been some improvement on it since I wrote that.

Have you checked the Basho products one of which is Riak, and it’s written in Erlang?

I am not affiliated but heard people praising them. Never had the chance to try any of their products so far though.

Sorry, but I haven’t used the driver, so not aware of the current limitations (if any) I was going through the discussion on the previously mentioned thread and thought it wasn’t actively maintained.

I think Riak is more of a Key-Value store than a NoSQL database. Also it is eventually consistent and doesn’t support atomic updates.

I’ll admit there hasn’t been much work done on the driver lately, the last commit was about a month ago, but it is still maintained. If you give it a look and there are some features that are not currently in there, just post an issue and we can probably get it sorted out.

what is the nature of the data? using postgres with GitHub - timescale/timescaledb: A time-series database for high-performance real-time analytics packaged as a Postgres extension · GitHub or GitHub - citusdata/citus: Distributed PostgreSQL as an extension · GitHub comes to mind.. admittingly I would think “normal” postgres is also up for the job..

that being said I would cautiously warn against changing both the DB and the App layer(to elixir I assume) at the same time.. but all depends on complexity etc. etc.

I would try and get something going using the old DB and Elixir (perhaps reverse proxy the Java app and then build out slowly.. Migrating from Rails to Elixir, bit by bit - #3 by outlog)

Yep, even raw-bog-standard PostgreSQL has fantastic nosql style storage with far more features than something like mongodb. Although I personally always question why someone thinks they need a nosql style storage, having a properly typed system is always far safer and often much faster.

The data has multiple objects which can be owned by multiple owners (sub-systems). A subsystem can replace the current object with a new object and assign its properties to different subsystems. The number of levels of the number of object is non-deterministic. It depends on the runtime inputs. And we also do a lot of scheduling based on priority, cost optimisation, etc on top of these subsystems. We have borrowed some concepts from FBP as well. I think modelling such kind of data in a traditional database isn’t a good idea.