The starting point for CQL is the CQL query . A CQL query is a single statement that defines how input events are to be processed and transformed into output events.
Oracle Event Processing considers an event as a collection of named key-value pairs. This is sometimes known as tuples. Each one of these pairs defines an attribute or property of the event, so henceforth we shall refer to them as event properties . Considering this, a better definition of a CQL query is that it specifies how particular properties of the input events are processed and result into output events with their own set of properties.
Let's take a look at an example. Consider an event e1
that contains two properties, p1
and p2
, whose values are respectively set to 1
and "hi"
. We will represent this event as follows:
e1 => {p1 = 1, p2 = "hi"}
Next, the CQL query Q1
simply transforms this input event into an output event containing just p1
and dropping p2
. So, the output for the input e1...