changes in pOperators for issue 423
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
index 32089e2..d745abd 100644
--- a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
@@ -110,7 +110,7 @@
         }
         
         IPredicateEvaluatorFactoryProvider predEvaluatorFactoryProvider = context.getPredicateEvaluatorFactoryProvider();
-        IPredicateEvaluatorFactory predEvaluatorFactory = predEvaluatorFactoryProvider.getPredicateEvaluatorFactory(keysLeft, keysRight);
+        IPredicateEvaluatorFactory predEvaluatorFactory = ( predEvaluatorFactoryProvider == null ? null : predEvaluatorFactoryProvider.getPredicateEvaluatorFactory(keysLeft, keysRight));
         
         RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op),
                 propagatedSchema, context);
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java
index a737f90..2c59151 100644
--- a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java
@@ -90,7 +90,7 @@
         }
         
         IPredicateEvaluatorFactoryProvider predEvaluatorFactoryProvider = context.getPredicateEvaluatorFactoryProvider();
-        IPredicateEvaluatorFactory predEvaluatorFactory = predEvaluatorFactoryProvider.getPredicateEvaluatorFactory(keysLeft, keysRight);
+        IPredicateEvaluatorFactory predEvaluatorFactory = ( predEvaluatorFactoryProvider == null ? null : predEvaluatorFactoryProvider.getPredicateEvaluatorFactory(keysLeft, keysRight));
         
         RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op),
                 propagatedSchema, context);