Does Azure Cosmos DB - Mongo API support aggregation

Question

I was looking to use cosmosdb to store time series data laid out in a document-centric design. Using the official mongodb driver I tried to write some simple aggregation statements; however, I received errors stating that $unwind and $group were not supported. Given that cosmosdb was touted as a drop-in replacement to mongodb did I miss a step or is aggregation not a supported feature.

retrieve.Aggregate().Unwind(i => i.Observations).Group(new BsonDocument {
        {"_id", "$Observations.Success"},
        {"avg", new BsonDocument{
        {"$avg", "$Observations.Duration"}
        }}
    }).ToList();

Answer 1

As of November 2017, Cosmos DB's MongoDB API now supports aggregation pipeline, including all of the pipeline stages identified in your original question ($unwind, $group).

Specifics of supported features are listed here.