Oracle Fusion Middleware C++ API Reference for Oracle Coherence
12c (12.1.2)
E26041-01

DistinctValues Class Reference

#include <coherence/util/aggregator/DistinctValues.hpp>

Inherits AbstractAggregator.

List of all members.

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Detailed Description

Return the set of unique values extracted from a set of entries in a Map.

If the set of entries is empty, an empty set is returned.

This aggregator could be used in combination with coherence::util::extractor::MultiExtractor allowing to collect all unique combinations (tuples) of a given set of attributes.

The DistinctValues aggregator covers a simple case of a more generic aggregation pattern implemented by the GroupAggregator, which in addition to collecting all distinct values or tuples, runs an aggregation against each distinct entry set (group).

Author:

djl 2008.05.12

Public Types
typedef spec::Handle	Handle
	DistinctValues Handle definition.
typedef spec::View	View
	DistinctValues View definition.
typedef spec::Holder	Holder
	DistinctValues Holder definition.
Protected Member Functions
	DistinctValues ()
	Default constructor (necessary for the PortableObject interface).
	DistinctValues (ValueExtractor::View vExtractor)
	Construct a DistinceValues aggregator.
virtual void	init (bool fFinal)
	Initialize the aggregation result. Parameters: fFinal  true is passed if the aggregation process that is being initialized must produce a final aggregation result; this will only be false if a parallel approach is being used and the initial (partial) aggregation process is being initialized
virtual void	process (Object::View vO, bool fFinal)
	Incorporate one aggregatable value into the result. If the fFinal parameter is true, the given object is a partial result (returned by an individual parallel aggregator) that should be incorporated into the final result; otherwise, the object is a value extracted from an coherence::util::InvocableMap::Entry. Parameters: vO  the value to incorporate into the aggregated result fFinal  true to indicate that the given object is a partial result returned by a parallel aggregator
virtual Object::Holder	finalizeResult (bool fFinal)
	Obtain the result of the aggregation. If the fFinal parameter is true, the returned object must be the final result of the aggregation; otherwise, the returned object will be treated as a partial result that should be incorporated into the final result. Parameters: fFinal  true to indicate that the final result of the aggregation process should be returned; this will only be false if a parallel approach is being used Returns: the result of the aggregation process
virtual Set::Handle	ensureSet ()
	Return a set that can be used to store distinct values, creating it if one has not already been created.
Protected Attributes
MemberHandle< Set >	m_hSet
	The resulting set of distinct values.

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Constructor & Destructor Documentation

DistinctValues

(

ValueExtractor::View

vExtractor

)

[protected]

Construct a DistinceValues aggregator.

Parameters:

vExtractor

the extractor that provides a value in the form of any object

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Member Function Documentation

virtual Set::Handle ensureSet

(

)

[protected, virtual]

Return a set that can be used to store distinct values, creating it if one has not already been created.

Returns:

a set that can be used to store distinct values

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The documentation for this class was generated from the following file:

• coherence/util/aggregator/DistinctValues.hpp

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