[Full disclosure, I work on the Azure Search team]

Cosmos DB has tight integration with Azure Search, to the point that you can choose to extend your Cosmos DB to Azure Search with a few clicks right from the portal to allow for full text search over this content.

You can learn more about how to do this at these two links: https://azure.microsoft.com/en-us/blog/adding-search-to-docu...

https://docs.microsoft.com/en-us/azure/search/search-howto-i...

Liam