diff --git a/core/src/main/java/geodb/ExtraSpatialFunctions.java b/core/src/main/java/geodb/ExtraSpatialFunctions.java
new file mode 100644
index 0000000..a437c69
--- /dev/null
+++ b/core/src/main/java/geodb/ExtraSpatialFunctions.java
@@ -0,0 +1,131 @@
+package geodb;
+
+import com.vividsolutions.jts.geom.Geometry;
+import com.vividsolutions.jts.geom.IntersectionMatrix;
+
+public class ExtraSpatialFunctions {
+
+	private ExtraSpatialFunctions() {
+	}
+
+	public static Integer dimension(byte[] wkb) {
+		Geometry geometry = GeoDB.gFromWKB(wkb);
+		if (geometry != null) {
+			return geometry.getDimension();
+		}
+		return null;
+	}
+
+	public static byte[] boundary(byte[] wkb) {
+		Geometry geometry = GeoDB.gFromWKB(wkb);
+		if (geometry != null) {
+			Geometry boundary = geometry.getBoundary();
+			if (boundary != null) {
+				return GeoDB.gToWKB(boundary);
+			}
+		}
+		return null;
+	}
+
+	public static boolean relate(byte[] wkb1, byte[] wkb2,
+			String intersectionPattern) {
+		Geometry geometry1 = GeoDB.gFromWKB(wkb1);
+		Geometry geometry2 = GeoDB.gFromWKB(wkb1);
+		if (geometry1 != null && geometry2 != null) {
+			return geometry1.relate(geometry2, intersectionPattern);
+		}
+		return false;
+	}
+
+	public static String relate(byte[] wkb1, byte[] wkb2) {
+		Geometry geometry1 = GeoDB.gFromWKB(wkb1);
+		Geometry geometry2 = GeoDB.gFromWKB(wkb1);
+		if (geometry1 != null && geometry2 != null) {
+			IntersectionMatrix result = geometry1.relate(geometry2);
+			return result.toString();
+		}
+		return null;
+	}
+
+	public static byte[] convexHull(byte[] wkb) {
+		Geometry geometry = GeoDB.gFromWKB(wkb);
+		if (geometry != null) {
+			Geometry boundary = geometry.convexHull();
+			if (boundary != null) {
+				return GeoDB.gToWKB(boundary);
+			}
+		}
+		return null;
+	}
+
+	public static byte[] difference(byte[] wkb1, byte[] wkb2) {
+		if (wkb1 == null) {
+			return null;
+		}
+		if (wkb2 == null) {
+			return wkb1;
+		}
+		Geometry geometry1 = GeoDB.gFromWKB(wkb1);
+		Geometry geometry2 = GeoDB.gFromWKB(wkb2);
+		if (geometry1 == null) {
+			return null;
+		}
+		if (geometry2 == null) {
+			return wkb1;
+		}
+
+		return GeoDB.gToWKB(geometry1.difference(geometry2));
+	}
+
+	public static byte[] intersection(byte[] wkb1, byte[] wkb2) {
+		if (wkb1 == null || wkb2 == null) {
+			return null;
+		}
+		Geometry geometry1 = GeoDB.gFromWKB(wkb1);
+		Geometry geometry2 = GeoDB.gFromWKB(wkb2);
+		if (geometry1 == null || geometry2 == null) {
+			return null;
+		}
+
+		return GeoDB.gToWKB(geometry1.intersection(geometry2));
+	}
+
+	public static byte[] symdifference(byte[] wkb1, byte[] wkb2) {
+		if (wkb1 == null) {
+			return wkb2;
+		}
+		if (wkb2 == null) {
+			return wkb1;
+		}
+		Geometry geometry1 = GeoDB.gFromWKB(wkb1);
+		Geometry geometry2 = GeoDB.gFromWKB(wkb2);
+		if (geometry1 == null) {
+			return GeoDB.gToWKB(geometry2);
+		}
+		if (geometry2 == null) {
+			return GeoDB.gToWKB(geometry1);
+		}
+
+		return GeoDB.gToWKB(geometry1.symDifference(geometry2));
+	}
+
+	public static byte[] union(byte[] wkb1, byte[] wkb2) {
+		if (wkb1 == null) {
+			return wkb2;
+		}
+		if (wkb2 == null) {
+			return wkb1;
+		}
+		Geometry geometry1 = GeoDB.gFromWKB(wkb1);
+		Geometry geometry2 = GeoDB.gFromWKB(wkb2);
+		if (geometry1 == null) {
+			return GeoDB.gToWKB(geometry2);
+		}
+		if (geometry2 == null) {
+			return GeoDB.gToWKB(geometry1);
+		}
+
+		return GeoDB.gToWKB(geometry1.union(geometry2));
+	}
+
+}
diff --git a/core/src/main/java/geodb/aggregate/Extent.java b/core/src/main/java/geodb/aggregate/Extent.java
new file mode 100644
index 0000000..40035d5
--- /dev/null
+++ b/core/src/main/java/geodb/aggregate/Extent.java
@@ -0,0 +1,34 @@
+package geodb.aggregate;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import com.vividsolutions.jts.geom.Geometry;
+
+public class Extent extends GeoAggregateFunction {
+
+	private Geometry result;
+
+	@Override
+	protected void add(Geometry geometry) {
+		if (result == null) {
+			result = geometry;
+		} else {
+			if (geometry != null) {
+				result=result.union(geometry.getEnvelope());
+			}
+		}
+	}
+
+	@Override
+	protected Geometry getGeometryResult() {
+		if (result!=null){
+			return result.getEnvelope();
+		}
+		return null;
+	}
+
+	public void init(Connection arg0) throws SQLException {
+		result=null;
+	}
+}
diff --git a/core/src/main/java/geodb/aggregate/GeoAggregateFunction.java b/core/src/main/java/geodb/aggregate/GeoAggregateFunction.java
new file mode 100644
index 0000000..36e5e9e
--- /dev/null
+++ b/core/src/main/java/geodb/aggregate/GeoAggregateFunction.java
@@ -0,0 +1,58 @@
+package geodb.aggregate;
+
+import geodb.GeoDB;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.sql.SQLException;
+import java.sql.Types;
+
+import org.h2.api.AggregateFunction;
+
+import com.vividsolutions.jts.geom.Geometry;
+import com.vividsolutions.jts.io.InputStreamInStream;
+import com.vividsolutions.jts.io.ParseException;
+import com.vividsolutions.jts.io.WKBReader;
+
+public abstract class GeoAggregateFunction implements AggregateFunction{
+
+
+	private Geometry createGeometry(ByteArrayInputStream stream) {
+		InputStreamInStream inputStreamInStream = new InputStreamInStream(stream);
+		Geometry geometry=null;
+		try {
+			geometry = new WKBReader().read(inputStreamInStream );
+		} catch (IOException e) {
+			throw new IllegalArgumentException("given geometry can not be found",e);
+		} catch (ParseException e) {
+			throw new IllegalArgumentException("given geometry is not valid",e);
+		}
+		return geometry;
+		
+	}
+
+	protected abstract void add(Geometry geometry);
+	protected abstract Geometry getGeometryResult();
+	
+	public final void add(Object arg0) throws SQLException {
+		if (arg0 != null) {
+			Geometry geometry = createGeometry((ByteArrayInputStream) arg0);
+			if (geometry!=null){
+				add(geometry);
+			}
+		}
+	}
+
+	public final Object getResult() throws SQLException {
+		Geometry geometryResult = getGeometryResult();
+		if (geometryResult!=null){
+			return GeoDB.gToWKB(geometryResult);
+		}
+		return null;
+	}
+
+	public final int getType(int[] arg0) throws SQLException {
+		return Types.BLOB;
+	}
+
+}
\ No newline at end of file
diff --git a/core/src/main/java/geodb/aggregate/Union.java b/core/src/main/java/geodb/aggregate/Union.java
new file mode 100644
index 0000000..4db4683
--- /dev/null
+++ b/core/src/main/java/geodb/aggregate/Union.java
@@ -0,0 +1,31 @@
+package geodb.aggregate;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import com.vividsolutions.jts.geom.Geometry;
+
+public class Union extends GeoAggregateFunction {
+
+	private Geometry result;
+
+	@Override
+	protected void add(Geometry geometry) {
+		if (result == null) {
+			result = geometry;
+		} else {
+			if (geometry != null) {
+				result=result.union(geometry);
+			}
+		}
+	}
+
+	@Override
+	protected Geometry getGeometryResult() {
+		return result;
+	}
+
+	public void init(Connection arg0) throws SQLException {
+		result=null;
+	}
+}
diff --git a/core/src/main/resources/geodb/geodb.sql b/core/src/main/resources/geodb/geodb.sql
index 8a19106..7f30bf5 100644
--- a/core/src/main/resources/geodb/geodb.sql
+++ b/core/src/main/resources/geodb/geodb.sql
@@ -11,13 +11,17 @@ CREATE ALIAS ST_AsEWKT FOR "geodb.GeoDB.ST_AsEWKT"
 CREATE ALIAS ST_AsHexEWKB FOR "geodb.GeoDB.ST_AsHexEWKB"
 CREATE ALIAS ST_AsText FOR "geodb.GeoDB.ST_AsText"
 CREATE ALIAS ST_BBOX FOR "geodb.GeoDB.ST_BBox"
+CREATE ALIAS ST_Boundary FOR "geodb.ExtraSpatialFunctions.boundary"
 CREATE ALIAS ST_Buffer FOR "geodb.GeoDB.ST_Buffer" 
 CREATE ALIAS ST_Centroid FOR "geodb.GeoDB.ST_Centroid"
 CREATE ALIAS ST_Crosses FOR "geodb.GeoDB.ST_Crosses"
 CREATE ALIAS ST_Contains FOR "geodb.GeoDB.ST_Contains"
+CREATE ALIAS ST_ConvexHull FOR "geodb.ExtraSpatialFunctions.convexHull"
 CREATE ALIAS ST_DWithin FOR "geodb.GeoDB.ST_DWithin"
 CREATE ALIAS ST_Disjoint FOR "geodb.GeoDB.ST_Disjoint"
 CREATE ALIAS ST_Distance FOR "geodb.GeoDB.ST_Distance"
+CREATE ALIAS ST_Difference FOR "geodb.ExtraSpatialFunctions.difference"
+CREATE ALIAS ST_Dimension FOR "geodb.ExtraSpatialFunctions.dimension"
 CREATE ALIAS ST_Envelope FOR "geodb.GeoDB.ST_Envelope"
 CREATE ALIAS ST_Equals FOR "geodb.GeoDB.ST_Equals"
 CREATE ALIAS ST_GeoHash FOR "geodb.GeoDB.ST_GeoHash"
@@ -25,6 +29,7 @@ CREATE ALIAS ST_GeomFromEWKB FOR "geodb.GeoDB.ST_GeomFromEWKB"
 CREATE ALIAS ST_GeomFromEWKT FOR "geodb.GeoDB.ST_GeomFromEWKT"
 CREATE ALIAS ST_GeomFromText FOR "geodb.GeoDB.ST_GeomFromText"
 CREATE ALIAS ST_GeomFromWKB FOR "geodb.GeoDB.ST_GeomFromWKB"
+CREATE ALIAS ST_Intersection FOR "geodb.ExtraSpatialFunctions.intersection"
 CREATE ALIAS ST_Intersects FOR "geodb.GeoDB.ST_Intersects"
 CREATE ALIAS ST_IsEmpty FOR "geodb.GeoDB.ST_IsEmpty"
 CREATE ALIAS ST_IsSimple FOR "geodb.GeoDB.ST_IsSimple"
@@ -32,10 +37,13 @@ CREATE ALIAS ST_IsValid FOR "geodb.GeoDB.ST_IsValid"
 CREATE ALIAS ST_MakePoint FOR "geodb.GeoDB.ST_MakePoint"
 CREATE ALIAS ST_MakeBox2D FOR "geodb.GeoDB.ST_MakeBox2D"
 CREATE ALIAS ST_Overlaps FOR "geodb.GeoDB.ST_Overlaps"
+CREATE ALIAS ST_Relate FOR "geodb.ExtraSpatialFunctions.relate"
 CREATE ALIAS ST_SRID FOR "geodb.GeoDB.ST_SRID"
 CREATE ALIAS ST_SetSRID FOR "geodb.GeoDB.ST_SetSRID"
 CREATE ALIAS ST_Simplify FOR "geodb.GeoDB.ST_Simplify"
+CREATE ALIAS ST_SymDifference FOR "geodb.ExtraSpatialFunctions.symdifference"
 CREATE ALIAS ST_Touches FOR "geodb.GeoDB.ST_Touches"
+CREATE ALIAS ST_Union FOR "geodb.ExtraSpatialFunctions.union"
 CREATE ALIAS ST_Within FOR "geodb.GeoDB.ST_Within"
 CREATE ALIAS Version FOR "geodb.GeoDB.Version"
 CREATE DOMAIN POINT AS BLOB
@@ -46,3 +54,5 @@ CREATE DOMAIN MULTILINESTRING AS BLOB
 CREATE DOMAIN MULTIPOLYGON AS BLOB
 CREATE DOMAIN GEOMETRYCOLLECTION AS BLOB
 CREATE DOMAIN GEOMETRY AS BLOB
+CREATE AGGREGATE EXTENT FOR "geodb.aggregate.Extent"
+CREATE AGGREGATE ST_UNION FOR "geodb.aggregate.Union"
diff --git a/core/src/test/java/geodb/ExtraSpatialFunctionsTest.java b/core/src/test/java/geodb/ExtraSpatialFunctionsTest.java
new file mode 100644
index 0000000..e11dea4
--- /dev/null
+++ b/core/src/test/java/geodb/ExtraSpatialFunctionsTest.java
@@ -0,0 +1,158 @@
+package geodb;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vividsolutions.jts.geom.Geometry;
+import com.vividsolutions.jts.io.InputStreamInStream;
+import com.vividsolutions.jts.io.ParseException;
+import com.vividsolutions.jts.io.WKBReader;
+
+public class ExtraSpatialFunctionsTest extends GeoDBTestSupport {
+
+    @Before
+    public void setup() throws Exception {
+        super.setUp();
+        Statement st = cx.createStatement();
+        st.execute("DROP TABLE IF EXISTS _GEODB");
+        st.execute("DROP TABLE IF EXISTS spatial");
+        st.execute("DROP TABLE IF EXISTS spatial_hatbox");
+        st.execute("DROP TABLE IF EXISTS noindex");
+        st.close();
+        GeoDB.InitGeoDB(cx);
+    }
+ 
+    
+    @Test
+    public void test_dimension() throws SQLException, IOException, ParseException {
+    	insert_three_points();
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select st_dimension(geom) from spatial");
+        rs.next();
+        int srid = rs.getInt(1);
+        st.close();
+        assertThat(srid, is(0));
+    }
+
+    @Test
+    public void test_boundary() throws SQLException, IOException, ParseException {
+    	insert_three_points();
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select st_boundary(geom) from spatial");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(0.0));
+    }
+
+    @Test
+    public void test_relate() throws SQLException, IOException, ParseException {
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("SELECT ST_Relate(ST_GeomFromText('POINT(1 2)',4326), ST_Buffer(ST_GeomFromText('POINT(1 2)',4326),2))");
+        rs.next();
+        String result = rs.getString(1);
+        st.close();
+      //I don't really understand this function so not sure if the result is correct. At least the result of both tests seems consistent.
+        assertThat(result, is("0FFFFFFF2"));
+    }
+
+    @Test
+    public void test_relate_with_matrix() throws SQLException, IOException, ParseException {
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("SELECT ST_Relate(ST_GeomFromText('POINT(1 2)',4326), ST_Buffer(ST_GeomFromText('POINT(1 2)',4326),2), '0FFFFFFF2')");
+        rs.next();
+        boolean result = rs.getBoolean(1);
+        st.close();
+    	//I don't really understand this function so not sure if the result is correct. At least the result of both tests seems consistent.
+        assertTrue(result);
+    }
+
+    @Test
+    public void test_convexHull() throws SQLException, IOException, ParseException {
+    	insert_three_points();
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select st_convexhull(geom) from spatial");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(0.0));
+    }
+
+    
+    @Test
+    public void test_difference() throws SQLException, IOException, ParseException {
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select ST_Difference(" +
+        													 "ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)," +
+        													 "ST_GeomFromText('POLYGON((5 5, 5 10, 10 10, 10 5, 5 5))', 4326))");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(75.0));
+    }
+    
+    @Test
+    public void test_intersection() throws SQLException, IOException, ParseException {
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select ST_Intersection(" +
+				 "ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)," +
+				 "ST_GeomFromText('POLYGON((5 5, 5 10, 10 10, 10 5, 5 5))', 4326))");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(25.0));
+    }
+
+    @Test
+    public void test_symdifference() throws SQLException, IOException, ParseException {
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select ST_SymDifference(" +
+				 "ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)," +
+				 "ST_GeomFromText('POLYGON((5 5, 5 15, 10 15, 10 5, 5 5))', 4326))");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(100.0));
+    }
+
+
+    @Test
+    public void test_union() throws SQLException, IOException, ParseException {
+    	Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select ST_Union(" +
+				 "ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))', 4326)," +
+				 "ST_GeomFromText('POLYGON((5 5, 5 15, 10 15, 10 5, 5 5))', 4326))");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(125.0));
+    }
+
+    private void insert_three_points() throws SQLException{
+    	Statement st = cx.createStatement();
+        st.execute("CREATE TABLE spatial (id INT AUTO_INCREMENT PRIMARY KEY, geom BLOB)");
+        st.execute("INSERT INTO spatial (geom) VALUES (ST_GeomFromText('POINT(0 0)', 4326))");
+        st.execute("INSERT INTO spatial (geom) VALUES (ST_GeomFromText('POINT(1 1)', 4326))");
+        st.execute("INSERT INTO spatial (geom) VALUES (ST_GeomFromText('POINT(2 2)', 4326))");
+        st.close();
+    }
+    
+    
+
+}
diff --git a/core/src/test/java/geodb/aggregate/AggregateTest.java b/core/src/test/java/geodb/aggregate/AggregateTest.java
new file mode 100644
index 0000000..fec94b7
--- /dev/null
+++ b/core/src/test/java/geodb/aggregate/AggregateTest.java
@@ -0,0 +1,64 @@
+package geodb.aggregate;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import geodb.GeoDB;
+import geodb.GeoDBTestSupport;
+
+import java.io.InputStream;
+import java.sql.ResultSet;
+import java.sql.Statement;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vividsolutions.jts.geom.Geometry;
+import com.vividsolutions.jts.io.InputStreamInStream;
+import com.vividsolutions.jts.io.WKBReader;
+
+public class AggregateTest extends GeoDBTestSupport {
+
+    @Before
+    public void setup() throws Exception {
+        super.setUp();
+        
+        Statement st = cx.createStatement();
+        st.execute("DROP TABLE IF EXISTS _GEODB");
+        st.execute("DROP TABLE IF EXISTS spatial");
+        st.execute("DROP TABLE IF EXISTS spatial_hatbox");
+        st.execute("DROP TABLE IF EXISTS noindex");
+        st.close();
+        GeoDB.InitGeoDB(cx);
+      
+        st = cx.createStatement();
+        st.execute("CREATE TABLE spatial (id INT AUTO_INCREMENT PRIMARY KEY, geom BLOB)");
+        st.execute("INSERT INTO spatial (geom) VALUES (ST_GeomFromText('POINT(0 0)', 4326))");
+        st.execute("INSERT INTO spatial (geom) VALUES (ST_GeomFromText('POINT(1 1)', 4326))");
+        st.execute("INSERT INTO spatial (geom) VALUES (ST_GeomFromText('POINT(2 2)', 4326))");
+        st.close();
+    }
+ 
+    @Test
+    public void test_extent() throws Exception {
+        Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select extent(geom) from spatial");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(4.0));
+    }
+
+    @Test
+    public void test_union() throws Exception {
+        Statement st = cx.createStatement();
+        ResultSet rs = st.executeQuery("select st_union(geom) from spatial");
+        rs.next();
+        InputStream binaryStream = rs.getBinaryStream(1);
+        Geometry geometry = new WKBReader().read(new InputStreamInStream(binaryStream));
+        st.close();
+        assertThat(geometry.getArea(), is(0.0));
+    }
+
+
+}
diff --git a/core/src/test/java/geodb/aggregate/ExtentTest.java b/core/src/test/java/geodb/aggregate/ExtentTest.java
new file mode 100644
index 0000000..406280e
--- /dev/null
+++ b/core/src/test/java/geodb/aggregate/ExtentTest.java
@@ -0,0 +1,112 @@
+package geodb.aggregate;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import geodb.GeoDB;
+
+import java.sql.SQLException;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vividsolutions.jts.geom.Coordinate;
+import com.vividsolutions.jts.geom.Geometry;
+import com.vividsolutions.jts.geom.GeometryFactory;
+import com.vividsolutions.jts.geom.LinearRing;
+import com.vividsolutions.jts.geom.impl.CoordinateArraySequence;
+
+public class ExtentTest {
+
+	private Extent extent;
+	
+	private GeometryFactory factory;
+	
+	
+	@Before
+	public void init_extent() throws SQLException{
+		extent=new Extent();
+		extent.init(null);
+	}
+
+	@Before
+	public void init_geometry_factory(){
+		factory=new GeometryFactory();
+	}
+	
+	@Test
+	public void extent_empty_collection() throws SQLException {
+		Object result = extent.getResult();
+		assertThat(result, is(nullValue()));
+	}
+
+	@Test
+	public void extent_one_point() throws SQLException{
+		extent.add(createPoint(3, 5));
+		Object result = extent.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		assertThat(envelope.getArea(), is(0.0));
+		assertThat(envelope, is(equalTo(createPoint(3, 5))));
+	}
+
+
+	@Test
+	public void extent_two_points() throws SQLException{
+		extent.add(createPoint(3, 5));
+		extent.add(createPoint(5, 3));
+		Object result = extent.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		
+		assertThat(envelope.getArea(), is(4.0));
+		assertTrue(envelope.contains(createPoint(4, 4)));
+		assertTrue(envelope.contains(createPoint(4.99999, 4.9999)));
+		assertFalse(envelope.contains(createPoint(5.00001, 5.00001)));
+	}
+
+	@Test
+	public void extent_triangle_polygon() throws SQLException{
+		extent.add(createPolygon(new Coordinate[]{new Coordinate(0, 1),new Coordinate(2, 2),new Coordinate(2, 0),new Coordinate(0, 1)}));
+		Object result = extent.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		
+		assertThat(envelope.getArea(), is(4.0));
+		assertTrue(envelope.contains(createPoint(1, 1)));
+		assertTrue(envelope.contains(createPoint(1.99999, 1.9999)));
+		assertFalse(envelope.contains(createPoint(2.00001, 2.00001)));
+		assertTrue(envelope.contains(createPoint(0.00001, 0.00001)));
+	}
+	
+	@Test
+	public void extent_two_triangle_polygon() throws SQLException{
+		extent.add(createPolygon(new Coordinate[]{new Coordinate(0, 1),new Coordinate(2, 2),new Coordinate(2, 0),new Coordinate(0, 1)}));
+		extent.add(createPolygon(new Coordinate[]{new Coordinate(1, 1),new Coordinate(3, 2),new Coordinate(3, 0),new Coordinate(1, 1)}));
+		Object result = extent.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		
+		assertThat(envelope.getArea(), is(6.0));
+		assertTrue(envelope.contains(createPoint(1, 1)));
+		assertTrue(envelope.contains(createPoint(2.99999, 1.9999)));
+		assertFalse(envelope.contains(createPoint(3.00001, 2.00001)));
+		assertTrue(envelope.contains(createPoint(0.00001, 0.00001)));
+	}
+
+
+	
+	private Geometry createPoint(double x,double y){
+		return factory.createPoint(new Coordinate(x, y));
+	}
+	
+	private Geometry createPolygon(Coordinate[] coordinates){
+		return factory.createPolygon(new LinearRing(new CoordinateArraySequence(coordinates), factory),null);
+	}
+
+}
diff --git a/core/src/test/java/geodb/aggregate/UnionTest.java b/core/src/test/java/geodb/aggregate/UnionTest.java
new file mode 100644
index 0000000..8686c1e
--- /dev/null
+++ b/core/src/test/java/geodb/aggregate/UnionTest.java
@@ -0,0 +1,112 @@
+package geodb.aggregate;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import geodb.GeoDB;
+
+import java.sql.SQLException;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vividsolutions.jts.geom.Coordinate;
+import com.vividsolutions.jts.geom.Geometry;
+import com.vividsolutions.jts.geom.GeometryFactory;
+import com.vividsolutions.jts.geom.LinearRing;
+import com.vividsolutions.jts.geom.impl.CoordinateArraySequence;
+
+public class UnionTest {
+
+	private Union union;
+	
+	private GeometryFactory factory;
+	
+	
+	@Before
+	public void init_extent() throws SQLException{
+		union=new Union();
+		union.init(null);
+	}
+
+	@Before
+	public void init_geometry_factory(){
+		factory=new GeometryFactory();
+	}
+	
+	@Test
+	public void extent_empty_collection() throws SQLException {
+		Object result = union.getResult();
+		assertThat(result, is(nullValue()));
+	}
+
+	@Test
+	public void extent_one_point() throws SQLException{
+		union.add(createPoint(3, 5));
+		Object result = union.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		assertThat(envelope.getArea(), is(0.0));
+		assertThat(envelope, is(equalTo(createPoint(3, 5))));
+	}
+
+
+	@Test
+	public void extent_two_points() throws SQLException{
+		union.add(createPoint(3, 5));
+		union.add(createPoint(5, 3));
+		Object result = union.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry geomResult = GeoDB.gFromWKB((byte[]) result);
+		
+		assertThat(geomResult.getArea(), is(0.0));
+		assertTrue(geomResult.contains(createPoint(3, 5)));
+		assertTrue(geomResult.contains(createPoint(5, 3)));
+		assertFalse(geomResult.contains(createPoint(4, 4)));
+	}
+
+	@Test
+	public void extent_triangle_polygon() throws SQLException{
+		union.add(createPolygon(new Coordinate[]{new Coordinate(0, 1),new Coordinate(2, 2),new Coordinate(2, 0),new Coordinate(0, 1)}));
+		Object result = union.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		
+		assertThat(envelope.getArea(), is(2.0));
+		assertTrue(envelope.contains(createPoint(1, 1)));
+		assertTrue(envelope.contains(createPoint(1.99999, 1.9999)));
+		assertFalse(envelope.contains(createPoint(2.00001, 2.00001)));
+		assertFalse(envelope.contains(createPoint(0, 0)));
+	}
+	
+	@Test
+	public void extent_two_triangle_polygon() throws SQLException{
+		union.add(createPolygon(new Coordinate[]{new Coordinate(0, 1),new Coordinate(2, 2),new Coordinate(2, 0),new Coordinate(0, 1)}));
+		union.add(createPolygon(new Coordinate[]{new Coordinate(1, 1),new Coordinate(3, 2),new Coordinate(3, 0),new Coordinate(1, 1)}));
+		Object result = union.getResult();
+		assertThat(result, is(not(nullValue())));
+		Geometry envelope = GeoDB.gFromWKB((byte[]) result);
+		
+		assertThat(envelope.getArea(), is(3.5));
+		assertTrue(envelope.contains(createPoint(1, 1)));
+		assertTrue(envelope.contains(createPoint(2.99999, 1.9999)));
+		assertFalse(envelope.contains(createPoint(3.00001, 2.00001)));
+		assertFalse(envelope.contains(createPoint(0, 0)));
+	}
+
+
+	
+	private Geometry createPoint(double x,double y){
+		return factory.createPoint(new Coordinate(x, y));
+	}
+	
+	private Geometry createPolygon(Coordinate[] coordinates){
+		return factory.createPolygon(new LinearRing(new CoordinateArraySequence(coordinates), factory),null);
+	}
+
+}