Teiid provides the capability to obtain partial results in the event of data source unavailability or failure. This is especially useful when unioning information from multiple sources, or when doing a left outer join, where you are appending columns to a master record, but still want the record if the extra information is not available.

A source is considered to be unavailable if the connection factory that is associated with the source generates an exception in response to a query. The exception will be propagated to the query processor, where it will become a warning on the statement. For more information about partial results and SQLWarning objects, see Partial Results Mode in the Client Developer’s Guide.