RDF Subgraph Query Based on Common Subgraph in Distributed Environment

Algorithm 1

CRTQ (, M(v))

Input: Composite relation tree , adjacency table M(v)

Output: Query result set Ω() = {Ω(), Ω(), …, Ω()}

FOR EACH

   Ω₁ = CALLSubgraphMatching ();

   IF ∃dj.Leaf(v)Ω₁THENΩ() = Ω₁;

   j++;

   Ω(T) = Ω()∪Ω(); //Get the matching result set of

END FOR

RETURNΩ(T);

FUNCTIONSubgraphMatching ()

   IF=d.rootTHENR ← CALLStarDecomposition ();

   WHILER ≠ ∅DO

   t ←1, ←R.dequeue;

   CALLmap(∅, M(v));

   IFt >1 THEN

   CALLmap(∅, β); //β∈Ω()

   Ω() = CALLreduce(, Ω(), Ω()));

   END IF(

   t++;

   END WHILE

   ELSE

   R ← CALLStarDecomposition ();

   WHILER ≠ ∅DO

   t ←1, ←R.dequeue;

   CALLmap(∅, Ω(.Parent)); //query in the result set of the parent graph

   IFt >1 THEN

   CALLmap(∅, β); //β∈Ω()

   Ω() = CALLreduce(, (Ω(), Ω()));

   END IF

   t++;

   END WHILE

   END IF

RETURNΩ();

 FUNCTIONmap(∅, M(v) or β)

   IF input M(v) THEN

      Ω() ← CALLStarMatching (, M(v));

      IFt =1 THEN

         β ← Ω();

         RETURN (∅, β);

      ELSE

         FOR EACHβ∈Ω()

            ; //get the matching result of as the key value

            RETURN (, β);

         END FOR

      END IF

   ELSE

      ;

      RETURN (, β); //the input value is Ω(), the output is (, β)

   END IF

 FUNCTIONreduce(, (Ω(), Ω()))

    FOR EACH

      RETURN; //get the current matching result set Ω()

    END FOR