Relation Output

The Relation Output operator sends out groups of tuples that reflect its input. When an event triggers a change in a relation result, the operator sends out changes rather than an entire result each time a triggering event is received.

The Relation Output operator sends out groups of tuples that reflect changes in the relation result. Whenever an event triggers a change in the relation result, the operator sends out records with a tag on the end. If the tag is a plus sign (+), then the record has been added. If the tag is a minus sign (-), then the record has been deleted.

If a change occurs as a result of the triggering event such that a record changes, IEP sends a delete record matching the changed record. IEP sends an add record when there is an updated or new version of that record. The operator only sends out change events rather than repeatedly sending the entire result.

If a triggering event enters into the event process, but the result of the final relation from that event does not change, then the relation output is not triggered and data is not sent.

Use the Relation Output operator to provide a summary of data that has been added or deleted.

To Create a Relation Output Operator

1. Drag a Relation Output operator from the Palette to the Design view.

2. Double-click the Relation Output operator.

   The property editor opens.

3. If you want to include a timestamp on the output, then select the Include Timestamp check box.

4. Click OK.