Support of HStores when using Dictionary<string,string> or as a new field attribute.

HStores (key values) are very good in certain scenarios (logging/auditing) and complex parsing is easier to do in .NET than in SQL.

Custom SQL that SELECT's data is easy, but not easy to insert/save hstore in custom sql.

Also Npgsql already supports them.

More info here:
https://forums.servicestack.net/t/cannot-insert-idictionary-string-string-into-hstore-column/6894