Count Value Occurrence

Performs count aggregation with Siddhi CEP engine.

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Description

Performs an aggregation based on a given field and outputs the number of occurrences. Example: Count the number of vehicle positions per vehicleId. The Count aggregation requires a time window, used to perform the count aggregation and a field used to aggregate values.

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Required input

Does not have any specific input requirements.

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Configuration

FieldToCount

Specifies the field containing the values that should be counted.

TimeWindowSize

Specifies the size of the time window and consequently the number of values that are aggregated each time.

Time Window Scale

Specifies the scale/unit of the time window. There are three different time scales to choose from: seconds, minutes or hours.

Output

The output event is composed of two fields. The field "value" specifies the value to count. The second field "count" returns the number of occurrences. Example:

{
  'value': 'vehicleId', 
  'count': 12
}