JoinHashTable → StringDictionary Relation

File in QueryEngine/JoinHashTable	Includes file in StringDictionary
Runtime / HashJoinKeyHandlers.h	StringDictionary.h
Runtime / HashJoinKeyHandlers.h	StringDictionaryProxy.h
Runtime / HashJoinRuntime.cpp	StringDictionary.h
Runtime / HashJoinRuntime.cpp	StringDictionaryProxy.h