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The idea behind the temporal feature is that you can use any normal function and the function does not need to know about the temporal feature. This is achieved by a simple trick: the non-temporal version of the expression is automatically evaluated for each point in time in the prediction time interval. The temporal attributes are solved for the points in time, create a non-temporal value which is then used to evaluate the function in a non-temporal manner. Then, the single results are stacked together to create a temporal output attribute. This is what the temporal feature does for you so you don't have to worry about this when writing your expressions.

The translation rules for the single operators detect if a temporal attribute is used in the expression(s). Then, a TemporalRelationalExpression is created instead if a RelationalExpression. The output of a temporal expression is typically a GenericTemporalType. Because it is not feasible to always create a temporal function, a simple map is used that maps from the time to the values. This new temporal attribute can of course be used in other expressions with any kind of function.

Direct Temporal Functions

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Operators

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PredictionTime

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Map

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Select

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Join

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