1. It looks like the database connection folder in the repository tab works fine for small databases. The bigger the database, the longer it takes. All my databases of interest are huge, so I cannot use this RapidMiner feature.
2. I just created a new process and I dropped the "Read Database" widget on the form and I used it to connect to both my Oracle and Teradata databases. It worked and it brought back data. Good enough for me.
The issue is with the TerraData driver. The way we treat TerraData causes problems with the database repository view. On the other hand, all of the database operators still work and the connection is fine. I.E. you can use the read database operator and pull in the data from the TerraData database connection even though the repository view gives you an error.