Package com.complexible.stardog.plan.aggregates

Interface Aggregate

  • All Superinterfaces:
    java.lang.AutoCloseable, Copyable<com.complexible.stardog.plan.filter.Expression>, com.complexible.stardog.plan.filter.Expression, Function
    public interface Aggregate
extends Function, java.lang.AutoCloseable

    A Function which computes an aggregated value over a group of solutions during query execution.

    Since:
    1.1
    Version:
    6.0
    Author:
    Michael Grove, Pavel Klinov
    See Also:
    Aggregates

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Interface Description
      static class  Aggregate.ErrorBehaviour
      Define behaviour of this aggregate when the input is unbound / erroneous

    • Method Summary

      All Methods Instance Methods Abstract Methods Default Methods 
      Modifier and Type Method Description
      void close()
      Disposes of the internal state.
      Aggregate copy()
      Create a deep copy of the object which does not share any references with the original.
      com.complexible.stardog.plan.filter.expr.ValueOrError evaluate​(com.complexible.stardog.plan.filter.ValueSolution theValueSolution)
      The return value of evaluating an Aggregate is not necessarily the aggregated value, and can even be null.
      com.complexible.stardog.plan.filter.expr.ValueOrError get()
      Get the aggregated value
      com.complexible.stardog.plan.filter.Expression getArg()
      Get the argument expression
      Aggregate.ErrorBehaviour getErrorBehaviour()  
      default boolean isAppropriateDataType​(Datatype theDataType)
      boolean isDistinct()
      Return whether or not the Aggregate has a distinct modifier applied to it
      default boolean isFixedSizeAggregate()
      void reset()
      Resets the internal state of the aggregate so it can start over.

      • Methods inherited from interface com.complexible.stardog.plan.filter.Expression

        accept, couldRaiseError, getArgs, replaceArg, setArgs

    • Method Detail

      • evaluate

        com.complexible.stardog.plan.filter.expr.ValueOrError evaluate​(com.complexible.stardog.plan.filter.ValueSolution theValueSolution)
        The return value of evaluating an Aggregate is not necessarily the aggregated value, and can even be null. In many cases the aggregate may be computing a value, as with Avg, rather than something like a running total or a value from the group. In these instances, it is not worth computing the aggregated value since it's not used until the entire group is processed and retrieved via get(). Some aggregates may choose to return the current aggregated value here, but null will often be the return value of this method for aggregates.
        Specified by:
        evaluate in interface com.complexible.stardog.plan.filter.Expression

      • get

        com.complexible.stardog.plan.filter.expr.ValueOrError get()
        Get the aggregated value
        Returns:
        the value

      • isDistinct

        boolean isDistinct()
        Return whether or not the Aggregate has a distinct modifier applied to it
        Returns:
        true if distinct, false otherwise

      • isFixedSizeAggregate

        default boolean isFixedSizeAggregate()
        

        

        Returns:
        

        true if corresponding aggregate is being applied to the decimal value with fixed size,
 else otherwise;
 
        

        

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      • 

        isAppropriateDataType
        

        default boolean isAppropriateDataType​(Datatype theDataType)
        

        

        

        Parameters:
        

        theDataType - - dataType;
        

        Returns:
        

        true if corresponding aggregate can be applied for the corresponding type
 during Functor's calculation, false otherwise;
 
        

        

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      • 

        getErrorBehaviour
        

        Aggregate.ErrorBehaviour getErrorBehaviour()
        

        

        Returns:
        

        value indicating whether this aggregate can produce unbound or error results
        

        

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      • 

        copy
        

        Aggregate copy()
        

        Create a deep copy of the object which does not share any references with the original.
        

        

        Specified by:
        

        copy in interface Copyable<com.complexible.stardog.plan.filter.Expression>
        

        Specified by:
        

        copy in interface Function
        

        Returns:
        

        a copy of the object
        

        

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      • 

        getArg
        

        com.complexible.stardog.plan.filter.Expression getArg()
        

        Get the argument expression
        

        

        Returns:
        

        the argument expression
        

        

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      • 

        reset
        

        void reset()
        

        Resets the internal state of the aggregate so it can start over.
        

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      • 

        close
        

        void close()
        

        Disposes of the internal state.
        

        

        Specified by:
        

        close in interface java.lang.AutoCloseable
        

        

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