Index: java/engine/org/apache/derby/impl/sql/execute/DMLWriteResultSet.java
===================================================================
--- java/engine/org/apache/derby/impl/sql/execute/DMLWriteResultSet.java	(revision 598683)
+++ java/engine/org/apache/derby/impl/sql/execute/DMLWriteResultSet.java	(working copy)
@@ -21,6 +21,8 @@
 
 package org.apache.derby.impl.sql.execute;
 
+import java.io.InputStream;
+
 import org.apache.derby.iapi.types.DataValueDescriptor;
 import org.apache.derby.iapi.sql.execute.NoPutResultSet;
 import org.apache.derby.iapi.services.io.StreamStorable;
@@ -148,10 +150,29 @@
 					heapIx :
 					baseRowReadMap[heapIx];
 
+                
 				DataValueDescriptor col = row.getColumn(readIx+1);
+				InputStream stream = ((StreamStorable)col).returnStream();
 				((StreamStorable)col).loadStream();
+				// DERBY-3238 
+				// fix up any duplicate streams, for instance in the case of an update with a trigger,
+				// all the columns are read as update columns even if they are not updated, so 
+				// the update column will still have a reference to the original stream.
+				// If we knew from this context that this was an update and we knew the number
+				// of columns in the base table we would be able to calculate exactly the offset to 
+				// check, but we don't have that information from this context.
+				// If DERBY-1482 is fixed, perhaps this code can be removed.
+				
+				if (stream != null)
+					for (int i = 1; i <= row.nColumns(); i++)
+					{
+						DataValueDescriptor c = row.getColumn(i);
+						if (c instanceof StreamStorable)
+							if (((StreamStorable)c).returnStream() == stream)
+								row.setColumn(i, col.getClone());
+					}
+				}
 			}
-		}
 	}
 
 	/**
Index: java/testing/org/apache/derbyTesting/functionTests/tests/lang/TriggerTest.java
===================================================================
--- java/testing/org/apache/derbyTesting/functionTests/tests/lang/TriggerTest.java	(revision 598683)
+++ java/testing/org/apache/derbyTesting/functionTests/tests/lang/TriggerTest.java	(working copy)
@@ -20,6 +20,7 @@
  */
 package org.apache.derbyTesting.functionTests.tests.lang;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.Reader;
@@ -398,6 +399,124 @@
         ((List) TRIGGER_INFO.get()).add(info);  
     }
     
+    /** 
+     * Test for DERBY-3238 trigger fails with IOException if triggering table has large lob.
+     * 
+     * @throws SQLException
+     * @throws IOException
+     */
+    public void testClobInTriggerTable() throws SQLException, IOException
+    {
+        String trig = " create trigger t_lob1 after update of str1 on lob1 ";
+        trig = trig + " REFERENCING OLD AS old NEW AS new FOR EACH ROW MODE DB2SQL ";
+        trig = trig + " insert into t_lob1_log(oldvalue, newvalue) values (old.str1, new.str1)";
+        Connection conn = getConnection();
+
+        Statement s = conn.createStatement();
+        
+        s.executeUpdate("create table LOB1 (str1 Varchar(80), b_lob BLOB(50M))");
+        s.executeUpdate("create table t_lob1_log(oldvalue varchar(80), newvalue varchar(80), chng_time timestamp default current_timestamp)");
+        s.executeUpdate(trig);
+        conn.commit();      
+        testClobSize(conn, s, 1024);
+        testClobSize(conn, s, 16384);
+        testClobSize(conn, s, 32658);
+     
+        testClobSize(conn, s, 32659);
+      
+        testClobSize(conn, s, 1024 *32 -1);
+        testClobSize(conn, s, 1024 *32);
+        testClobSize(conn, s, 1024 *32+1);
+        testClobSize(conn, s, 1024 *64 -1);
+        testClobSize(conn, s, 1024 *64);
+        testClobSize(conn, s, 1024 *64+1);
+        s.executeUpdate("drop table lob1");
+        s.executeUpdate("drop table t_lob1_log");
+    }
+   
+    private static void testClobSize(Connection conn, Statement s, int blobSize) throws SQLException, IOException {
+        // --- add a blob
+        PreparedStatement ps = conn.prepareStatement("INSERT INTO LOB1 VALUES (?, ?)");
+        
+        ps.setString(1, blobSize +"");
+
+
+        byte[] arr = new byte[blobSize];
+        for (int i = 0; i < arr.length; i++)
+            arr[i] = (byte)8;
+
+        // - set the value of the input parameter to the input stream
+        ps.setBinaryStream(2, new ByteArrayInputStream(arr) , blobSize);
+        ps.execute();
+        conn.commit();
+
+        // Now executing update to fire trigger
+        s.executeUpdate("update LOB1 set str1 = str1 || ' '");
+        s.executeUpdate("DELETE FROM LOB1");
+   
+    }
+    
+    
+    /** 
+     * Test for DERBY-3238 trigger fails with IOException if triggering table has large lob.
+     * 
+     * @throws SQLException
+     * @throws IOException
+     */
+    public void testBlobInTriggerTable() throws SQLException, IOException
+    {
+        String trig = " create trigger t_lob1 after update of str1 on lob1 ";
+        trig = trig + " REFERENCING OLD AS old NEW AS new FOR EACH ROW MODE DB2SQL ";
+        trig = trig + " insert into t_lob1_log(oldvalue, newvalue) values (old.str1, new.str1)";
+        Connection conn = getConnection();
+
+        Statement s = conn.createStatement();
+        
+        s.executeUpdate("create table LOB1 (str1 Varchar(80), b_lob BLOB(50M))");
+        s.executeUpdate("create table t_lob1_log(oldvalue varchar(80), newvalue varchar(80), chng_time timestamp default current_timestamp)");
+        s.executeUpdate(trig);
+        conn.commit();      
+        testBlobSize(conn, s, 1024);
+        testBlobSize(conn, s, 16384);
+        testBlobSize(conn, s, 32658);
+     
+        testBlobSize(conn, s, 32659);
+      
+        testBlobSize(conn, s, 1024 *32 -1);
+        testBlobSize(conn, s, 1024 *32);
+        testBlobSize(conn, s, 1024 *32+1);
+        testBlobSize(conn, s, 1024 *64 -1);
+        testBlobSize(conn, s, 1024 *64);
+        testBlobSize(conn, s, 1024 *64+1);
+        testBlobSize(conn, s, 1024 *1024* 15);
+        s.executeUpdate("drop table lob1");
+        s.executeUpdate("drop table t_lob1_log");
+    }
+    
+    private static void testBlobSize(Connection conn, Statement s, int blobSize) throws SQLException, IOException {
+        // --- add a blob
+        PreparedStatement ps = conn.prepareStatement("INSERT INTO LOB1 VALUES (?, ?)");
+        
+        ps.setString(1, blobSize +"");
+
+
+        byte[] arr = new byte[blobSize];
+        for (int i = 0; i < arr.length; i++)
+            arr[i] = (byte)8;
+
+        // - set the value of the input parameter to the input stream
+        ps.setBinaryStream(2, new ByteArrayInputStream(arr) , blobSize);
+        ps.execute();
+        conn.commit();
+
+        // Now executing update to fire trigger
+        s.executeUpdate("update LOB1 set str1 = str1 || ' '");
+        s.executeUpdate("DELETE FROM LOB1");
+   
+    }
+    
+    
+    
     /**
      * Test that the action statement of a trigger
      * can work with all datatypes.