diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java
index 9c06d2c..ab68b68 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java
@@ -38,10 +38,12 @@
 import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
 import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
-import org.apache.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
 import org.apache.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
 import org.apache.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import org.apache.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty.PropertyType;
 import org.apache.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
 import org.apache.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
 import org.apache.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
@@ -52,7 +54,6 @@
 import org.apache.hyracks.algebricks.core.algebra.properties.PropertiesUtil;
 import org.apache.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
 import org.apache.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
-import org.apache.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty.PropertyType;
 import org.apache.hyracks.algebricks.core.algebra.util.OperatorPropertiesUtil;
 
 public abstract class AbstractPreclusteredGroupByPOperator extends AbstractPhysicalOperator {
@@ -231,6 +232,22 @@
         return null;
     }
 
+    protected int[] getFdColumns(GroupByOperator gby, IOperatorSchema inputSchema) throws AlgebricksException {
+        int numFds = gby.getDecorList().size();
+        int fdColumns[] = new int[numFds];
+        int j = 0;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                throw new AlgebricksException("pre-sorted group-by expects variable references.");
+            }
+            VariableReferenceExpression v = (VariableReferenceExpression) expr;
+            LogicalVariable decor = v.getVariableReference();
+            fdColumns[j++] = inputSchema.findVariable(decor);
+        }
+        return fdColumns;
+    }
+
     private static LogicalVariable getLhsGbyVar(GroupByOperator gby, LogicalVariable var) {
         for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : gby.getGroupByList()) {
             ILogicalExpression e = ve.second.getValue();
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java
index 6e8933c..2772ee7 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java
@@ -20,18 +20,12 @@
 
 import java.util.List;
 
-import org.apache.commons.lang3.mutable.Mutable;
-
 import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
-import org.apache.hyracks.algebricks.common.utils.Pair;
 import org.apache.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
-import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
 import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
-import org.apache.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
 import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
 import org.apache.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
 import org.apache.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
-import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
 import org.apache.hyracks.algebricks.core.jobgen.impl.JobGenContext;
@@ -65,19 +59,8 @@
             throws AlgebricksException {
         int keys[] = JobGenHelper.variablesToFieldIndexes(columnList, inputSchemas[0]);
         GroupByOperator gby = (GroupByOperator) op;
-        int numFds = gby.getDecorList().size();
-        int fdColumns[] = new int[numFds];
         IVariableTypeEnvironment env = context.getTypeEnvironment(op);
-        int j = 0;
-        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList()) {
-            ILogicalExpression expr = p.second.getValue();
-            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
-                throw new AlgebricksException("pre-sorted group-by expects variable references.");
-            }
-            VariableReferenceExpression v = (VariableReferenceExpression) expr;
-            LogicalVariable decor = v.getVariableReference();
-            fdColumns[j++] = inputSchemas[0].findVariable(decor);
-        }
+        int fdColumns[] = getFdColumns(gby, inputSchemas[0]);
         // compile subplans and set the gby op. schema accordingly
         AlgebricksPipeline[] subplans = compileSubplans(inputSchemas[0], gby, opSchema, context);
         IAggregatorDescriptorFactory aggregatorFactory = new NestedPlansAccumulatingAggregatorFactory(subplans, keys,
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java
index e0df2f9..a636d10 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java
@@ -20,17 +20,12 @@
 
 import java.util.List;
 
-import org.apache.commons.lang3.mutable.Mutable;
 import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
-import org.apache.hyracks.algebricks.common.utils.Pair;
 import org.apache.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
-import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
 import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
-import org.apache.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
 import org.apache.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
 import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
 import org.apache.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
-import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
@@ -70,18 +65,7 @@
             throws AlgebricksException {
         int keys[] = JobGenHelper.variablesToFieldIndexes(columnList, inputSchemas[0]);
         GroupByOperator gby = (GroupByOperator) op;
-        int numFds = gby.getDecorList().size();
-        int fdColumns[] = new int[numFds];
-        int j = 0;
-        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList()) {
-            ILogicalExpression expr = p.second.getValue();
-            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
-                throw new AlgebricksException("pre-sorted group-by expects variable references.");
-            }
-            VariableReferenceExpression v = (VariableReferenceExpression) expr;
-            LogicalVariable decor = v.getVariableReference();
-            fdColumns[j++] = inputSchemas[0].findVariable(decor);
-        }
+        int fdColumns[] = getFdColumns(gby, inputSchemas[0]);
         // compile subplans and set the gby op. schema accordingly
         AlgebricksPipeline[] subplans = compileSubplans(inputSchemas[0], gby, opSchema, context);
         IAggregatorDescriptorFactory aggregatorFactory;