This operator merges the incomming tuples from each input stream. If an inorder approach is used (the default), the operator conserves the order.

Remark: This could lead to a blocking behaviour when no data is delivered via one input stream. You could use the Heartbeat operator Operator for input streams with a low data rate.

Parameter

none

Example

PQL

output = UNION(left, right)

CQL

SELECT * FROM left UNION SELECT * FROM rigtht