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  • group_by: An optional list of attributes over which the grouping should occur.
  • aggregations: A list if elements where each element contains up to four string:
    • The name of the aggregate function, e.g. MAX
    • The input attribute over which the aggregation should be done
    • The name of the output attribute for this aggregation
    • The optional type of the output. If not given, DOUBLE will be used.
  • dumpAtValueCount: This parameter is used in the interval approach. Here a result is generated, each time an aggregation cannot be changed anymore. This leads to fewer results with a larger validity. With this parameter the production rate can be raised. A value of 1 means, that for every new element the aggregation operator receives new output elements are generated. This leads to more results with a shorter validity.
  • outputPA: This parameter allow to dump partial aggregates instead of evaluted values. The partial aggregates can be send to other aggregation operators and do a final aggregation (e.g. in case of distribution). The input schema of an aggregate operator that read partial aggregates must state a datatype that is a partial aggregated (see example below). Remark: Aggregate has one input and requires ordered input. To combine different parital aggregations e.g. a union operator is needed to reorder the input elements.
  • drainAtDone: Boolean, default true: If done is called, all not already written elements will be written.
  • drainAtClose: Boolean, default false: If close is called, all not already written elements will be written.
  • FastGrouping: Use hash code instead of compare to create group. Potentially unsafe!

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