Class QueryJoinOptimizer.JoinVisitor

    • Field Detail

      • boundVars

        java.util.Set<java.lang.String> boundVars
    • Constructor Detail

    • Method Detail

      • optimizePriorityJoin

        private void optimizePriorityJoin​(java.util.Set<java.lang.String> origBoundVars,
                                          TupleExpr join)
      • getJoinArgs

        protected <L extends java.util.List<TupleExpr>> L getJoinArgs​(TupleExpr tupleExpr,
                                                                      L joinArgs)
      • getStatementPatternVars

        protected java.util.List<Var> getStatementPatternVars​(TupleExpr tupleExpr)
      • fillVarFreqMap

        protected <M extends java.util.Map<Var,​java.lang.Integer>> void fillVarFreqMap​(java.util.List<Var> varList,
                                                                                             M varFreqMap)
      • getExtensions

        protected java.util.List<Extension> getExtensions​(java.util.List<TupleExpr> expressions)
      • getExtensionTupleExprs

        private java.util.List<TupleExpr> getExtensionTupleExprs​(java.util.List<TupleExpr> expressions)
      • getSubSelects

        protected java.util.List<TupleExpr> getSubSelects​(java.util.List<TupleExpr> expressions)
      • reorderSubselects

        protected java.util.List<TupleExpr> reorderSubselects​(java.util.List<TupleExpr> subSelects)
        Determines an optimal ordering of subselect join arguments, based on variable bindings. An ordering is considered optimal if for each consecutive element it holds that first of all its shared variables with all previous elements is maximized, and second, the union of all its variables with all previous elements is maximized.

        Example: reordering

           [f] [a b c] [e f] [a d] [b e]
         

        should result in:

           [a b c] [a d] [b e] [e f] [f]
         
        Parameters:
        subSelects - the original ordering of expressions
        Returns:
        the optimized ordering of expressions
      • getNextSubselect

        private TupleExpr getNextSubselect​(java.util.List<TupleExpr> currentList,
                                           java.util.List<TupleExpr> joinArgs)
      • selectNextTupleExpr

        protected TupleExpr selectNextTupleExpr​(java.util.List<TupleExpr> expressions,
                                                java.util.Map<TupleExpr,​java.lang.Double> cardinalityMap,
                                                java.util.Map<TupleExpr,​java.util.List<Var>> varsMap,
                                                java.util.Map<Var,​java.lang.Integer> varFreqMap)
        Selects from a list of tuple expressions the next tuple expression that should be evaluated. This method selects the tuple expression with highest number of bound variables, preferring variables that have been bound in other tuple expressions over variables with a fixed value.
      • getTupleExprCost

        protected double getTupleExprCost​(TupleExpr tupleExpr,
                                          java.util.Map<TupleExpr,​java.lang.Double> cardinalityMap,
                                          java.util.Map<TupleExpr,​java.util.List<Var>> varsMap,
                                          java.util.Map<Var,​java.lang.Integer> varFreqMap)
      • countConstantVars

        private int countConstantVars​(java.util.List<Var> vars)
      • getUnboundVars

        @Deprecated(forRemoval=true,
                    since="4.1.0")
        protected java.util.List<Var> getUnboundVars​(java.lang.Iterable<Var> vars)
        Deprecated, for removal: This API element is subject to removal in a future version.
      • getUnboundVars

        protected java.util.List<Var> getUnboundVars​(java.util.List<Var> vars)
      • getForeignVarFreq

        protected int getForeignVarFreq​(java.util.List<Var> ownUnboundVars,
                                        java.util.Map<Var,​java.lang.Integer> varFreqMap)