Are other database technologies required?

At the moment DeepSpace is designed to use an azure CosmosDB back end, however this may be frustrating for people who don't want to use azure.

Is there a requirement for a database which can be run locally? SQL Server for example?

Start by reviewing how the current Azure CosmosDB backend is used and whether the issue has an established requirement for local database support. Compare the proposed SQL Server example with the existing backend assumptions; done would require a decided scope and documented implementation requirements for local use.

Written by the indexing model from the issue text.