diff --git a/asterix-app/src/test/resources/runtimets/queries/spatial/circle_accessor.aql b/asterix-app/src/test/resources/runtimets/queries/spatial/circle_accessor.aql
new file mode 100644
index 0000000..1d48ebd
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/spatial/circle_accessor.aql
@@ -0,0 +1,14 @@
+/*
+ * Description      :   Test spatial accessors
+ * Expected Result  :   Success
+ * Date             :   Oct 17, 2012
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+use dataverse test;
+
+write output to nc1:"rttest/spatial_circle_accessor.adm";
+
+let $circle := create-circle(create-point(6.0,3.0), 1.0)
+return {"circle-radius": get-radius($circle), "circle-center": get-center($circle)}
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/queries/spatial/line_accessor.aql b/asterix-app/src/test/resources/runtimets/queries/spatial/line_accessor.aql
new file mode 100644
index 0000000..2085436
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/spatial/line_accessor.aql
@@ -0,0 +1,16 @@
+/*
+ * Description      :   Test spatial accessors
+ * Expected Result  :   Success
+ * Date             :   Oct 17, 2012
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+use dataverse test;
+
+write output to nc1:"rttest/spatial_line_accessor.adm";
+
+let $line := create-line(create-point(100.6,999.4), create-point(-872.0,-876.9))
+let $line_list := get-points($line)
+for $p in $line_list
+return $p
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/queries/spatial/point_accessor.aql b/asterix-app/src/test/resources/runtimets/queries/spatial/point_accessor.aql
new file mode 100644
index 0000000..c408630
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/spatial/point_accessor.aql
@@ -0,0 +1,14 @@
+/*
+ * Description      :   Test spatial accessors
+ * Expected Result  :   Success
+ * Date             :   Oct 17, 2012
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+use dataverse test;
+
+write output to nc1:"rttest/spatial_point_accessor.adm";
+
+let $point := create-point(2.3,5.0)
+return {"x-coordinate": get-x($point), "y-coordinate": get-y($point)}
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/queries/spatial/polygon_accessor.aql b/asterix-app/src/test/resources/runtimets/queries/spatial/polygon_accessor.aql
new file mode 100644
index 0000000..a181648
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/spatial/polygon_accessor.aql
@@ -0,0 +1,16 @@
+/*
+ * Description      :   Test spatial accessors
+ * Expected Result  :   Success
+ * Date             :   Oct 17, 2012
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+use dataverse test;
+
+write output to nc1:"rttest/spatial_polygon_accessor.adm";
+
+let $polygon := create-polygon(create-point(1.0,1.0), create-point(2.0,2.0), create-point(3.0,3.0), create-point(4.0,4.0))
+let $polygon_list := get-points($polygon)
+for $p in $polygon_list
+return $p
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/queries/spatial/rectangle_accessor.aql b/asterix-app/src/test/resources/runtimets/queries/spatial/rectangle_accessor.aql
new file mode 100644
index 0000000..676888c
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/spatial/rectangle_accessor.aql
@@ -0,0 +1,16 @@
+/*
+ * Description      :   Test spatial accessors
+ * Expected Result  :   Success
+ * Date             :   Oct 17, 2012
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+use dataverse test;
+
+write output to nc1:"rttest/spatial_rectangle_accessor.adm";
+
+let $rectangle := create-rectangle(create-point(9.2,49.0), create-point(77.8,111.1))
+let $rectangle_list := get-points($rectangle)
+for $p in $rectangle_list
+return $p
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/queries/spatial/spatial_accessors.aql b/asterix-app/src/test/resources/runtimets/queries/spatial/spatial_accessors.aql
deleted file mode 100644
index e87bc24..0000000
--- a/asterix-app/src/test/resources/runtimets/queries/spatial/spatial_accessors.aql
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
- * Description      :   Test spatial accessors
- * Expected Result  :   Success
- * Date             :   Oct 16, 2012
- */
-
-drop dataverse test if exists;
-create dataverse test;
-use dataverse test;
-
-write output to nc1:"rttest/spatial_spatial_accessors.adm";
-
-let $point := create-point(2.3,5.0)
-let $circle := create-circle(create-point(6.0,3.0), 1.0)
-let $line := create-line(create-point(100.6,999.4), create-point(-872.0,-876.9))
-let $rectangle := create-rectangle(create-point(9.2,49.0), create-point(77.8,111.1))
-let $polygon := create-polygon(create-point(1.0,1.0), create-point(2.0,2.0), create-point(3.0,3.0), create-point(4.0,4.0))
-let $line_list := get-points($line)
-let $rectangle_list := get-points($rectangle)
-let $polygon_list := get-points($polygon)
-return {"x-coordinate": get-x($point), "y-coordinate": get-y($point), "circle-radius": get-radius($circle), "circle-center": get-center($circle), "line-first-point": $line_list[0], "line-second-point": $line_list[1], "rectangle-left-bottom-point": $rectangle_list[0], "rectangle-top-upper-point": $rectangle_list[1], "polygon-first-point": $polygon_list[0], "polygon-second-point": $polygon_list[1], "polygon-third-point": $polygon_list[2], "polygon-forth-point": $polygon_list[3]}
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/results/spatial/circle_accessor.adm b/asterix-app/src/test/resources/runtimets/results/spatial/circle_accessor.adm
new file mode 100644
index 0000000..8848521
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/results/spatial/circle_accessor.adm
@@ -0,0 +1 @@
+{ "circle-radius": 1.0d, "circle-center": point("6.0,3.0") }
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/results/spatial/line_accessor.adm b/asterix-app/src/test/resources/runtimets/results/spatial/line_accessor.adm
new file mode 100644
index 0000000..c6d1c06
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/results/spatial/line_accessor.adm
@@ -0,0 +1,2 @@
+point("100.6,999.4")
+point("-872.0,-876.9")
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/results/spatial/point_accessor.adm b/asterix-app/src/test/resources/runtimets/results/spatial/point_accessor.adm
new file mode 100644
index 0000000..0fa3fe4
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/results/spatial/point_accessor.adm
@@ -0,0 +1 @@
+{ "x-coordinate": 2.3d, "y-coordinate": 5.0d }
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/results/spatial/polygon_accessor.adm b/asterix-app/src/test/resources/runtimets/results/spatial/polygon_accessor.adm
new file mode 100644
index 0000000..12685ce
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/results/spatial/polygon_accessor.adm
@@ -0,0 +1,4 @@
+point("1.0,1.0")
+point("2.0,2.0")
+point("3.0,3.0")
+point("4.0,4.0")
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/results/spatial/rectangle_accessor.adm b/asterix-app/src/test/resources/runtimets/results/spatial/rectangle_accessor.adm
new file mode 100644
index 0000000..f198dff
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/results/spatial/rectangle_accessor.adm
@@ -0,0 +1,2 @@
+point("9.2,49.0")
+point("77.8,111.1")
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/results/spatial/spatial_accessors.adm b/asterix-app/src/test/resources/runtimets/results/spatial/spatial_accessors.adm
deleted file mode 100644
index 493a76e..0000000
--- a/asterix-app/src/test/resources/runtimets/results/spatial/spatial_accessors.adm
+++ /dev/null
@@ -1 +0,0 @@
-{ "x-coordinate": 2.3d, "y-coordinate": 5.0d, "circle-radius": 1.0d, "circle-center": point("6.0,3.0"), "line-first-point": point("100.6,999.4"), "line-second-point": point("-872.0,-876.9"), "rectangle-left-bottom-point": point("9.2,49.0"), "rectangle-top-upper-point": point("77.8,111.1"), "polygon-first-point": point("1.0,1.0"), "polygon-second-point": point("2.0,2.0"), "polygon-third-point": point("3.0,3.0"), "polygon-forth-point": point("4.0,4.0") }
\ No newline at end of file
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleCenterAccessor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleCenterAccessor.java
index 9d6aeda..577a1fb 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleCenterAccessor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleCenterAccessor.java
@@ -23,6 +23,7 @@
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.ADoubleSerializerDeserializer;
 import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
 import edu.uci.ics.asterix.om.base.AMutablePoint;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.base.APoint;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
@@ -44,6 +45,7 @@
 
     private static final FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "get-center", 1);
     private static final byte SER_CICLE_TAG = ATypeTag.CIRCLE.serialize();
+    private final static byte SER_NULL_TYPE_TAG = ATypeTag.NULL.serialize();
 
     public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
 
@@ -62,13 +64,16 @@
             @Override
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval = args[0].createEvaluator(argOut);
 
-                    private AMutablePoint aPoint = new AMutablePoint(0, 0);
                     @SuppressWarnings("unchecked")
-                    private ISerializerDeserializer<APoint> pointSerde = AqlSerializerDeserializerProvider.INSTANCE
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
+                    private final AMutablePoint aPoint = new AMutablePoint(0, 0);
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<APoint> pointSerde = AqlSerializerDeserializerProvider.INSTANCE
                             .getSerializerDeserializer(BuiltinType.APOINT);
 
                     @Override
@@ -85,12 +90,14 @@
                                         ACircleSerializerDeserializer.getCenterPointCoordinateOffset(Coordinate.X));
                                 cY = ADoubleSerializerDeserializer.getDouble(bytes,
                                         ACircleSerializerDeserializer.getCenterPointCoordinateOffset(Coordinate.Y));
+                                aPoint.setValue(cX, cY);
+                                pointSerde.serialize(aPoint, out);
+                            } else if (bytes[0] == SER_NULL_TYPE_TAG) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new AlgebricksException("get-center does not support the type: " + bytes[0]
                                         + " It is only implemented for CIRCLE.");
                             }
-                            aPoint.setValue(cX, cY);
-                            pointSerde.serialize(aPoint, out);
 
                         } catch (IOException e) {
                             throw new AlgebricksException(e);
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleRadiusAccessor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleRadiusAccessor.java
index 27a4c04..ffaae9e 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleRadiusAccessor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/CircleRadiusAccessor.java
@@ -23,6 +23,7 @@
 import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
 import edu.uci.ics.asterix.om.base.ADouble;
 import edu.uci.ics.asterix.om.base.AMutableDouble;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
 import edu.uci.ics.asterix.om.types.ATypeTag;
@@ -43,6 +44,7 @@
 
     private static final FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "get-radius", 1);
     private static final byte SER_CICLE_TAG = ATypeTag.CIRCLE.serialize();
+    private final static byte SER_NULL_TYPE_TAG = ATypeTag.NULL.serialize();
 
     public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
 
@@ -61,13 +63,16 @@
             @Override
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval = args[0].createEvaluator(argOut);
 
-                    private AMutableDouble aDouble = new AMutableDouble(0);
                     @SuppressWarnings("unchecked")
-                    private ISerializerDeserializer<ADouble> doubleSerde = AqlSerializerDeserializerProvider.INSTANCE
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
+                    private final AMutableDouble aDouble = new AMutableDouble(0);
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<ADouble> doubleSerde = AqlSerializerDeserializerProvider.INSTANCE
                             .getSerializerDeserializer(BuiltinType.ADOUBLE);
 
                     @Override
@@ -81,14 +86,15 @@
                             if (bytes[0] == SER_CICLE_TAG) {
                                 radius = ADoubleSerializerDeserializer.getDouble(bytes,
                                         ACircleSerializerDeserializer.getRadiusOffset());
+                                aDouble.setValue(radius);
+                                doubleSerde.serialize(aDouble, out);
+                            } else if (bytes[0] == SER_NULL_TYPE_TAG) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new AlgebricksException("get-radius does not support the type: " + bytes[0]
                                         + " It is only implemented for CIRCLE.");
                             }
 
-                            aDouble.setValue(radius);
-                            doubleSerde.serialize(aDouble, out);
-
                         } catch (IOException e) {
                             throw new AlgebricksException(e);
                         }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/LineRectanglePolygonAccessor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/LineRectanglePolygonAccessor.java
index ea9c599..68ff480 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/LineRectanglePolygonAccessor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/LineRectanglePolygonAccessor.java
@@ -28,6 +28,7 @@
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.ARectangleSerializerDeserializer;
 import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
 import edu.uci.ics.asterix.om.base.AMutablePoint;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.base.APoint;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
@@ -53,6 +54,7 @@
     private static final byte SER_LINE_TAG = ATypeTag.LINE.serialize();
     private static final byte SER_RECTANGLE_TAG = ATypeTag.RECTANGLE.serialize();
     private static final byte SER_POLYGON_TAG = ATypeTag.POLYGON.serialize();
+    private final static byte SER_NULL_TYPE_TAG = ATypeTag.NULL.serialize();
 
     public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
 
@@ -71,17 +73,20 @@
             @Override
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval = args[0].createEvaluator(argOut);
 
-                    private IAOrderedListBuilder listBuilder = new OrderedListBuilder();
-                    private ArrayBackedValueStorage inputVal = new ArrayBackedValueStorage();
-                    protected final AOrderedListType pointListType = new AOrderedListType(BuiltinType.APOINT, null);
+                    private final IAOrderedListBuilder listBuilder = new OrderedListBuilder();
+                    private final ArrayBackedValueStorage inputVal = new ArrayBackedValueStorage();
+                    private final AOrderedListType pointListType = new AOrderedListType(BuiltinType.APOINT, null);
 
-                    private AMutablePoint aPoint = new AMutablePoint(0, 0);
                     @SuppressWarnings("unchecked")
-                    private ISerializerDeserializer<APoint> pointSerde = AqlSerializerDeserializerProvider.INSTANCE
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
+                    private final AMutablePoint aPoint = new AMutablePoint(0, 0);
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<APoint> pointSerde = AqlSerializerDeserializerProvider.INSTANCE
                             .getSerializerDeserializer(BuiltinType.APOINT);
 
                     @Override
@@ -111,6 +116,7 @@
                                 aPoint.setValue(endX, endY);
                                 pointSerde.serialize(aPoint, inputVal.getDataOutput());
                                 listBuilder.addItem(inputVal);
+                                listBuilder.write(out, true);
 
                             } else if (bytes[0] == SER_RECTANGLE_TAG) {
                                 listBuilder.reset(pointListType);
@@ -132,6 +138,7 @@
                                 aPoint.setValue(x2, y2);
                                 pointSerde.serialize(aPoint, inputVal.getDataOutput());
                                 listBuilder.addItem(inputVal);
+                                listBuilder.write(out, true);
 
                             } else if (bytes[0] == SER_POLYGON_TAG) {
                                 int numOfPoints = AInt16SerializerDeserializer.getShort(bytes,
@@ -151,12 +158,13 @@
                                     pointSerde.serialize(aPoint, inputVal.getDataOutput());
                                     listBuilder.addItem(inputVal);
                                 }
+                                listBuilder.write(out, true);
+                            } else if (bytes[0] == SER_NULL_TYPE_TAG) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new AlgebricksException("get-points does not support the type: " + bytes[0]
                                         + " It is only implemented for LINE, RECTANGLE, or POLYGON.");
                             }
-                            listBuilder.write(out, true);
-
                         } catch (IOException e) {
                             throw new AlgebricksException(e);
                         }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointXCoordinateAccessor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointXCoordinateAccessor.java
index c619c4a..7fcfd20 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointXCoordinateAccessor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointXCoordinateAccessor.java
@@ -24,6 +24,7 @@
 import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
 import edu.uci.ics.asterix.om.base.ADouble;
 import edu.uci.ics.asterix.om.base.AMutableDouble;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
 import edu.uci.ics.asterix.om.types.ATypeTag;
@@ -44,6 +45,7 @@
 
     private static final FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "get-x", 1);
     private static final byte SER_POINT_TAG = ATypeTag.POINT.serialize();
+    private final static byte SER_NULL_TYPE_TAG = ATypeTag.NULL.serialize();
 
     public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
 
@@ -62,13 +64,16 @@
             @Override
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval = args[0].createEvaluator(argOut);
 
-                    private AMutableDouble aDouble = new AMutableDouble(0);
                     @SuppressWarnings("unchecked")
-                    private ISerializerDeserializer<ADouble> doubleSerde = AqlSerializerDeserializerProvider.INSTANCE
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
+                    private final AMutableDouble aDouble = new AMutableDouble(0);
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<ADouble> doubleSerde = AqlSerializerDeserializerProvider.INSTANCE
                             .getSerializerDeserializer(BuiltinType.ADOUBLE);
 
                     @Override
@@ -82,14 +87,15 @@
                             if (bytes[0] == SER_POINT_TAG) {
                                 x = ADoubleSerializerDeserializer.getDouble(bytes,
                                         APointSerializerDeserializer.getCoordinateOffset(Coordinate.X));
+                                aDouble.setValue(x);
+                                doubleSerde.serialize(aDouble, out);
+                            } else if (bytes[0] == SER_NULL_TYPE_TAG) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new AlgebricksException("get-x does not support the type: " + bytes[0]
                                         + " It is only implemented for POINT.");
                             }
 
-                            aDouble.setValue(x);
-                            doubleSerde.serialize(aDouble, out);
-
                         } catch (IOException e) {
                             throw new AlgebricksException(e);
                         }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointYCoordinateAccessor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointYCoordinateAccessor.java
index 4e6b71e..1c47efa 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointYCoordinateAccessor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/accessors/PointYCoordinateAccessor.java
@@ -24,6 +24,7 @@
 import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
 import edu.uci.ics.asterix.om.base.ADouble;
 import edu.uci.ics.asterix.om.base.AMutableDouble;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
 import edu.uci.ics.asterix.om.types.ATypeTag;
@@ -44,6 +45,7 @@
 
     private static final FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "get-y", 1);
     private static final byte SER_POINT_TAG = ATypeTag.POINT.serialize();
+    private final static byte SER_NULL_TYPE_TAG = ATypeTag.NULL.serialize();
 
     public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
 
@@ -62,13 +64,16 @@
             @Override
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval = args[0].createEvaluator(argOut);
 
-                    private AMutableDouble aDouble = new AMutableDouble(0);
                     @SuppressWarnings("unchecked")
-                    private ISerializerDeserializer<ADouble> doubleSerde = AqlSerializerDeserializerProvider.INSTANCE
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
+                    private final AMutableDouble aDouble = new AMutableDouble(0);
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<ADouble> doubleSerde = AqlSerializerDeserializerProvider.INSTANCE
                             .getSerializerDeserializer(BuiltinType.ADOUBLE);
 
                     @Override
@@ -82,14 +87,15 @@
                             if (bytes[0] == SER_POINT_TAG) {
                                 y = ADoubleSerializerDeserializer.getDouble(bytes,
                                         APointSerializerDeserializer.getCoordinateOffset(Coordinate.Y));
+                                aDouble.setValue(y);
+                                doubleSerde.serialize(aDouble, out);
+                            } else if (bytes[0] == SER_NULL_TYPE_TAG) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new AlgebricksException("get-y does not support the type: " + bytes[0]
                                         + " It is only implemented for POINT.");
                             }
 
-                            aDouble.setValue(y);
-                            doubleSerde.serialize(aDouble, out);
-
                         } catch (IOException e) {
                             throw new AlgebricksException(e);
                         }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialAreaDescriptor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialAreaDescriptor.java
index c641f1a..d4d1619 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialAreaDescriptor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialAreaDescriptor.java
@@ -9,9 +9,12 @@
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.ADoubleSerializerDeserializer;
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.AInt16SerializerDeserializer;
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.ARectangleSerializerDeserializer;
+import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
 import edu.uci.ics.asterix.om.types.ATypeTag;
+import edu.uci.ics.asterix.om.types.BuiltinType;
 import edu.uci.ics.asterix.om.types.EnumDeserializer;
 import edu.uci.ics.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
 import edu.uci.ics.asterix.runtime.evaluators.common.SpatialUtils;
@@ -20,6 +23,7 @@
 import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
 import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluator;
 import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.data.std.api.IDataOutputProvider;
 import edu.uci.ics.hyracks.data.std.util.ArrayBackedValueStorage;
@@ -44,9 +48,13 @@
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
 
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval = args[0].createEvaluator(argOut);
+
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
 
                     @Override
                     public void evaluate(IFrameTupleReference tuple) throws AlgebricksException {
@@ -66,11 +74,15 @@
                                         throw new AlgebricksException("Polygon must have at least 3 points");
                                     }
                                     area = Math.abs(SpatialUtils.polygonArea(argOut.getByteArray(), numOfPoints));
+                                    out.writeByte(ATypeTag.DOUBLE.serialize());
+                                    out.writeDouble(area);
                                     break;
                                 case CIRCLE:
                                     double radius = ADoubleSerializerDeserializer.getDouble(argOut.getByteArray(),
                                             ACircleSerializerDeserializer.getRadiusOffset());
                                     area = SpatialUtils.pi() * radius * radius;
+                                    out.writeByte(ATypeTag.DOUBLE.serialize());
+                                    out.writeDouble(area);
                                     break;
                                 case RECTANGLE:
                                     double x1 = ADoubleSerializerDeserializer.getDouble(argOut.getByteArray(),
@@ -87,13 +99,16 @@
                                             ARectangleSerializerDeserializer
                                                     .getUpperRightCoordinateOffset(Coordinate.Y));
                                     area = (x2 - x1) * (y2 - y1);
+                                    out.writeByte(ATypeTag.DOUBLE.serialize());
+                                    out.writeDouble(area);
+                                    break;
+                                case NULL:
+                                    nullSerde.serialize(ANull.NULL, out);
                                     break;
                                 default:
                                     throw new NotImplementedException("spatial-area does not support the type: " + tag
                                             + " It is only implemented for POLYGON, CIRCLE and RECTANGLE.");
                             }
-                            out.writeByte(ATypeTag.DOUBLE.serialize());
-                            out.writeDouble(area);
                         } catch (HyracksDataException hde) {
                             throw new AlgebricksException(hde);
                         } catch (IOException e) {
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialCellDescriptor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialCellDescriptor.java
index 1426f91..3d918d8 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialCellDescriptor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialCellDescriptor.java
@@ -10,6 +10,7 @@
 import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
 import edu.uci.ics.asterix.om.base.AMutablePoint;
 import edu.uci.ics.asterix.om.base.AMutableRectangle;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.base.ARectangle;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
@@ -46,20 +47,24 @@
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
 
-                    private DataOutput out = output.getDataOutput();
+                    private final DataOutput out = output.getDataOutput();
 
-                    private ArrayBackedValueStorage outInput0 = new ArrayBackedValueStorage();
-                    private ArrayBackedValueStorage outInput1 = new ArrayBackedValueStorage();
-                    private ArrayBackedValueStorage outInput2 = new ArrayBackedValueStorage();
-                    private ArrayBackedValueStorage outInput3 = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval0 = args[0].createEvaluator(outInput0);
-                    private ICopyEvaluator eval1 = args[1].createEvaluator(outInput1);
-                    private ICopyEvaluator eval2 = args[2].createEvaluator(outInput2);
-                    private ICopyEvaluator eval3 = args[3].createEvaluator(outInput3);
-                    private AMutableRectangle aRectangle = new AMutableRectangle(null, null);
-                    private AMutablePoint[] aPoint = { new AMutablePoint(0, 0), new AMutablePoint(0, 0) };
+                    private final ArrayBackedValueStorage outInput0 = new ArrayBackedValueStorage();
+                    private final ArrayBackedValueStorage outInput1 = new ArrayBackedValueStorage();
+                    private final ArrayBackedValueStorage outInput2 = new ArrayBackedValueStorage();
+                    private final ArrayBackedValueStorage outInput3 = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval0 = args[0].createEvaluator(outInput0);
+                    private final ICopyEvaluator eval1 = args[1].createEvaluator(outInput1);
+                    private final ICopyEvaluator eval2 = args[2].createEvaluator(outInput2);
+                    private final ICopyEvaluator eval3 = args[3].createEvaluator(outInput3);
+                    private final AMutableRectangle aRectangle = new AMutableRectangle(null, null);
+                    private final AMutablePoint[] aPoint = { new AMutablePoint(0, 0), new AMutablePoint(0, 0) };
+
                     @SuppressWarnings("unchecked")
-                    private ISerializerDeserializer<ARectangle> rectangleSerde = AqlSerializerDeserializerProvider.INSTANCE
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<ARectangle> rectangleSerde = AqlSerializerDeserializerProvider.INSTANCE
                             .getSerializerDeserializer(BuiltinType.ARECTANGLE);
 
                     @Override
@@ -96,6 +101,8 @@
                                 aPoint[1].setValue(x + xInc, y + yInc);
                                 aRectangle.setValue(aPoint[0], aPoint[1]);
                                 rectangleSerde.serialize(aRectangle, out);
+                            } else if (tag == ATypeTag.NULL) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new NotImplementedException("spatial-cell does not support the type: " + tag
                                         + " It is only implemented for POINT.");
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialDistanceDescriptor.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialDistanceDescriptor.java
index d83f62e..63032b9 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialDistanceDescriptor.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/SpatialDistanceDescriptor.java
@@ -7,9 +7,12 @@
 import edu.uci.ics.asterix.dataflow.data.nontagged.Coordinate;
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.ADoubleSerializerDeserializer;
 import edu.uci.ics.asterix.dataflow.data.nontagged.serde.APointSerializerDeserializer;
+import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
+import edu.uci.ics.asterix.om.base.ANull;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
 import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
 import edu.uci.ics.asterix.om.types.ATypeTag;
+import edu.uci.ics.asterix.om.types.BuiltinType;
 import edu.uci.ics.asterix.om.types.EnumDeserializer;
 import edu.uci.ics.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
 import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
@@ -17,6 +20,7 @@
 import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
 import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluator;
 import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.data.std.api.IDataOutputProvider;
 import edu.uci.ics.hyracks.data.std.util.ArrayBackedValueStorage;
@@ -42,11 +46,15 @@
             public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                 return new ICopyEvaluator() {
 
-                    private DataOutput out = output.getDataOutput();
-                    private ArrayBackedValueStorage outInput0 = new ArrayBackedValueStorage();
-                    private ArrayBackedValueStorage outInput1 = new ArrayBackedValueStorage();
-                    private ICopyEvaluator eval0 = args[0].createEvaluator(outInput0);
-                    private ICopyEvaluator eval1 = args[1].createEvaluator(outInput1);
+                    private final DataOutput out = output.getDataOutput();
+                    private final ArrayBackedValueStorage outInput0 = new ArrayBackedValueStorage();
+                    private final ArrayBackedValueStorage outInput1 = new ArrayBackedValueStorage();
+                    private final ICopyEvaluator eval0 = args[0].createEvaluator(outInput0);
+                    private final ICopyEvaluator eval1 = args[1].createEvaluator(outInput1);
+
+                    @SuppressWarnings("unchecked")
+                    private final ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
+                            .getSerializerDeserializer(BuiltinType.ANULL);
 
                     @Override
                     public void evaluate(IFrameTupleReference tuple) throws AlgebricksException {
@@ -76,6 +84,8 @@
                                     throw new NotImplementedException("spatial-distance does not support the type: "
                                             + tag1 + " It is only implemented for POINT.");
                                 }
+                            } else if (tag0 == ATypeTag.NULL || tag1 == ATypeTag.NULL) {
+                                nullSerde.serialize(ANull.NULL, out);
                             } else {
                                 throw new NotImplementedException("spatial-distance does not support the type: " + tag0
                                         + " It is only implemented for POINT.");
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/formats/NonTaggedDataFormat.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/formats/NonTaggedDataFormat.java
index 4665631..07c21fb 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/formats/NonTaggedDataFormat.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/formats/NonTaggedDataFormat.java
@@ -285,7 +285,6 @@
         temp.add(NonEmptyStreamAggregateDescriptor.FACTORY);
         temp.add(RangeDescriptor.FACTORY);
 
-        // Xiaoyu Ma add for numeric unary functions
         temp.add(NumericAbsDescriptor.FACTORY);
         temp.add(NumericCeilingDescriptor.FACTORY);
         temp.add(NumericFloorDescriptor.FACTORY);