Aggregate Operator: Tuple-Based Dimension Options

In the Aggregate operator Dimensions tab you can open the Edit Dimension dialog to add, edit, or remove dimensions from the Aggregate operator. With a tuple-based dimension, a new window will be established and evaluated based on the number of arriving tuples. For example, a tuple containing the aggregate results may be emitted and the window closed when it contains a certain number of tuples

The following table describes the options available in the Edit Dimension dialog for tuple-based dimensions.

TYPE = TUPLE

Category Options and Meaning
Opening policy: Select one of these options:

  • Do not open window based on this dimension: If selected, this dimension cannot cause the opening of a new window for the Aggregate.

  • Open per ... Advance: The amount by which to advance the window of tuples. Think of this setting as a slider for multiple windows (see the diagram in Example 1 of Using the Aggregate Operator for an illustration).

Note

The Offset option is disabled for tuple-based Aggregates, because each window is simply populated by a given number of tuples, rather than sets of tuples based on a field's value or arrival time.

Window size: Select one of these options:

  • Do not close window based on this dimension: If selected, this dimension cannot cause the closing of a new window for the Aggregate. If a new window is never opened, and Do not close... is selected, this creates an infinite sized window that never closes (for the life of the StreamBase Server).

  • Close and emit after [number] tuples: If selected, sets the size of the window. If the number of tuples is exceeded, the window is closed and an aggregate tuple is emitted.

Emission policy: Select one of these options:

  • No intermediate emissions based on this dimension: If selected, this dimension does not force an immediate emission of a results tuple (after applying the function's calculation to the tuples in the window).

  • Intermediate emission every [number] tuples: If selected, allows tuples to be emitted before the window closes. For example, you could emit a tuple for each tuple that arrives within a 30-tuple window, instead of waiting for 30 tuples to arrive and produce a close event.

Optional windows: For tuple-based aggregates, the only option is whether to enable Create partial windows.

When set, this option creates partial windows which encompass the values that would have occurred before the arrival of the first tuple. For example, where Advance is less than Size, additional windows would be opened to include the first tuple; these windows would start before the Time in the first tuple.


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