is there any way to execute an all-or-nothing transaction with both systems included? E.g.
using(transaction) {
DbContext.SaveChanges();
DocumentClient.DoStuff();
transaction.Commit();
}
EF Core does not seem to support Transaction Scope.
Cosmos DB and your other database (SQL DB) are completely separate. There's no way to wrap operations from both into a single transaction.
Cosmos DB will let you operate within its own transaction mechanism, via stored procedures: operations within a Cosmos DB stored procedure are "all or nothing." But... This is independent of a TransactionScope.