diff --git a/ext/session/sqlite3session.c b/ext/session/sqlite3session.c
index 86778d65f0..2ff0bc56fe 100644
--- a/ext/session/sqlite3session.c
+++ b/ext/session/sqlite3session.c
@@ -667,14 +667,14 @@ static void sessionAppendUpdate(
     u8 *pCsr = p->aRecord;
     sessionAppendByte(pBuf, SQLITE_UPDATE, pRc);
     for(i=0; i<sqlite3_column_count(pStmt); i++){
-      int nCopy = 0;
+      int bChanged = 0;
       int nAdvance;
       int eType = *pCsr;
       switch( eType ){
         case SQLITE_NULL:
           nAdvance = 1;
           if( sqlite3_column_type(pStmt, i)!=SQLITE_NULL ){
-            nCopy = 1;
+            bChanged = 1;
           }
           break;
 
@@ -691,7 +691,7 @@ static void sessionAppendUpdate(
               if( dVal==sqlite3_column_double(pStmt, i) ) break;
             }
           }
-          nCopy = 9;
+          bChanged = 1;
           break;
         }
 
@@ -706,21 +706,23 @@ static void sessionAppendUpdate(
           ){
             break;
           }
-          nCopy = nAdvance;
+          bChanged = 1;
         }
       }
-      if( abPK[i] ){
-        nCopy = nAdvance;
+
+      if( bChanged || abPK[i] ){
+        sessionAppendBlob(pBuf, pCsr, nAdvance, pRc);
+      }else{
+        sessionAppendByte(pBuf, 0, pRc);
       }
 
-      if( nCopy==0 ){
-        sessionAppendByte(pBuf, 0, pRc);
-        sessionAppendByte(&buf2, 0, pRc);
-      }else{
-        sessionAppendBlob(pBuf, pCsr, nCopy, pRc);
+      if( bChanged ){
         sessionAppendCol(&buf2, pStmt, i, pRc);
         bNoop = 0;
+      }else{
+        sessionAppendByte(&buf2, 0, pRc);
       }
+
       pCsr += nAdvance;
     }
 
@@ -1452,6 +1454,52 @@ static int sessionSelectRow(
   return rc;
 }
 
+static int sessionConstraintConflict(
+  sqlite3 *db,                    /* Database handle */
+  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
+  u8 *abPK,                       /* Primary key flags array */
+  sqlite3_stmt *pSelect,          /* SELECT statement from sessionSelectRow() */
+  int(*xConflict)(void *, int, sqlite3_changeset_iter*),
+  void *pCtx
+){
+  int res;
+  int rc;
+  int i;
+  int nCol;
+  int op;
+  const char *zDummy;
+
+  sqlite3changeset_op(pIter, &zDummy, &nCol, &op);
+  assert( op==SQLITE_UPDATE || op==SQLITE_INSERT );
+
+  /* Bind the new.* PRIMARY KEY values to the SELECT statement. */
+  for(i=0; i<nCol; i++){
+    if( abPK[i] ){
+      sqlite3_value *pVal;
+      if( op==SQLITE_UPDATE ) rc = sqlite3changeset_old(pIter, i, &pVal);
+      else                    rc = sqlite3changeset_new(pIter, i, &pVal);
+      if( rc!=SQLITE_OK ) return rc;
+      sqlite3_bind_value(pSelect, i+1, pVal);
+    }
+  }
+
+  if( SQLITE_ROW==sqlite3_step(pSelect) ){
+    /* There exists another row with the new.* primary key. */
+    pIter->pConflict = pSelect;
+    res = xConflict(pCtx, SQLITE_CHANGESET_CONFLICT, pIter);
+    pIter->pConflict = 0;
+    sqlite3_reset(pSelect);
+  }else{
+    /* No other row with the new.* primary key. */
+    rc = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ){
+      res = xConflict(pCtx, SQLITE_CHANGESET_CONSTRAINT, pIter);
+    }
+  }
+
+  return rc;
+}
+
 int sqlite3changeset_apply(
   sqlite3 *db,
   int nChangeset,
@@ -1479,6 +1527,8 @@ int sqlite3changeset_apply(
   sqlite3_stmt *pSelect = 0;      /* SELECT statement */
 
   rc = sqlite3_exec(db, "SAVEPOINT changeset_apply", 0, 0, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
   sqlite3changeset_start(&pIter, nChangeset, pChangeset);
   while( SQLITE_ROW==sqlite3changeset_next(pIter) ){
     int op;
@@ -1494,6 +1544,13 @@ int sqlite3changeset_apply(
       sqlite3_finalize(pInsert);
       sqlite3_finalize(pSelect);
       pSelect = pUpdate = pInsert = pDelete = 0;
+
+      if( (rc = sessionSelectRow(db, zTab, nCol, azCol, abPK, &pSelect))
+       || (rc = sessionUpdateRow(db, zTab, nCol, azCol, abPK, &pUpdate))
+       || (rc = sessionDeleteRow(db, zTab, nCol, azCol, abPK, &pDelete))
+      ){
+        break;
+      }
     }
 
     if( op==SQLITE_DELETE ){
@@ -1559,7 +1616,7 @@ int sqlite3changeset_apply(
         if( rc==SQLITE_OK ){
           if( pOld ) sqlite3_bind_value(pUpdate, i*3+1, pOld);
           sqlite3_bind_int(pUpdate, i*3+2, !!pNew);
-          if( pNew ) sqlite3_bind_value(pUpdate, i*3+3, pOld);
+          if( pNew ) sqlite3_bind_value(pUpdate, i*3+3, pNew);
         }
       }
       if( rc==SQLITE_OK ) rc = sqlite3_bind_int(pUpdate, nCol*3+1, 0);
@@ -1592,7 +1649,32 @@ int sqlite3changeset_apply(
           }
         }
       }else if( rc==SQLITE_CONSTRAINT ){
-        assert(0);
+        /* This may be a CONSTRAINT or CONFLICT error. It is a CONFLICT if
+        ** the only problem is a duplicate PRIMARY KEY, or a CONSTRAINT 
+        ** otherwise. */
+        int bPKChange = 0;
+
+        /* Check if the PK has been modified. */
+        rc = SQLITE_OK;
+        for(i=0; i<nCol && rc==SQLITE_OK; i++){
+          if( abPK[i] ){
+            sqlite3_value *pNew;
+            rc = sqlite3changeset_new(pIter, i, &pNew);
+            if( rc==SQLITE_OK && pNew ){
+              bPKChange = 1;
+              break;
+            }
+          }
+        }
+
+        if( bPKChange ){
+          /* See if there exists a row with a duplicate primary key. */
+          rc = sessionConstraintConflict(
+              db, pIter, abPK, pSelect, xConflict, pCtx
+          );
+        }else{
+          res = xConflict(pCtx, SQLITE_CHANGESET_CONSTRAINT, pIter);
+        }
       }
 
     }else{
@@ -1624,29 +1706,9 @@ int sqlite3changeset_apply(
       sqlite3_step(pInsert);
       rc = sqlite3_reset(pInsert);
       if( rc==SQLITE_CONSTRAINT && xConflict ){
-        int res;
-
-        /* Figure out if this is a primary key or other constraint. */
-        rc = sessionSelectRow(db, zTab, nCol, azCol, abPK, &pSelect);
-        for(i=0; rc==SQLITE_OK && i<nCol; i++){
-          if( abPK[i] ){
-            sqlite3_value *pVal;
-            rc = sqlite3changeset_new(pIter, i, &pVal);
-            if( rc==SQLITE_OK ) sqlite3_bind_value(pSelect, i+1, pVal);
-          }
-        }
-        if( rc!=SQLITE_OK ) break;
-        if( SQLITE_ROW==sqlite3_step(pSelect) ){
-          pIter->pConflict = pSelect;
-          res = xConflict(pCtx, SQLITE_CHANGESET_CONFLICT, pIter);
-          pIter->pConflict = 0;
-          sqlite3_reset(pSelect);
-        }else{
-          rc = sqlite3_reset(pSelect);
-          if( rc==SQLITE_OK ){
-            res = xConflict(pCtx, SQLITE_CHANGESET_CONSTRAINT, pIter);
-          }
-        }
+        rc = sessionConstraintConflict(
+              db, pIter, abPK, pSelect, xConflict, pCtx
+        );
       }
     }
   }
diff --git a/manifest b/manifest
index b3938bacd9..38e0a86e95 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sthe\ssqlite3changeset_apply()\sfunction.\sDoes\snot\syet\shandle\sall\scases.
-D 2011-03-11T19:05:52
+C Fix\ssome\sissues\swith\sUPDATE\schanges\sin\sthe\ssession\smodule.
+D 2011-03-12T17:22:46
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 27701a1653595a1f2187dc61c8117e00a6c1d50f
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -98,7 +98,7 @@ F ext/rtree/rtree_util.tcl 06aab2ed5b826545bf215fff90ecb9255a8647ea
 F ext/rtree/sqlite3rtree.h 1af0899c63a688e272d69d8e746f24e76f10a3f0
 F ext/rtree/tkt3363.test 142ab96eded44a3615ec79fba98c7bde7d0f96de
 F ext/rtree/viewrtree.tcl eea6224b3553599ae665b239bd827e182b466024
-F ext/session/sqlite3session.c 724a064f0d9a909c12dfb668b42ce007378f352e
+F ext/session/sqlite3session.c af63d87b8787c19b4a4b681f77331a9cc13d67af
 F ext/session/sqlite3session.h 3246613b20857e58f7419e4e26dbe9161677aff0
 F ext/session/test_session.c 1b4f278d0ae164e2d02c11f5e1f2df3a2567ba41
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895
@@ -639,7 +639,7 @@ F test/selectA.test 06d1032fa9009314c95394f2ca2e60d9f7ae8532
 F test/selectB.test f305cc6660804cb239aab4e2f26b0e288b59958b
 F test/selectC.test f9bf1bc4581b5b8158caa6e4e4f682acb379fb25
 F test/server1.test f5b790d4c0498179151ca8a7715a65a7802c859c
-F test/session1.test 6a2e0db809e44879cec5314a6fd238ad768d9723
+F test/session1.test 6ec522f3491fbdbf8a5b6c27f50b9e35f24e3dba
 F test/shared.test b9114eaea7e748a3a4c8ff7b9ca806c8f95cef3e
 F test/shared2.test 7f6ad2d857d0f4e5d6a0b9a897b5e56a6b6ea18c
 F test/shared3.test d69bdd5f156580876c5345652d21dc2092e85962
@@ -913,7 +913,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 75d5dff725dbb66d67d56ad042926f1daae56dbe
-R 7203b6a6763bad83d70ecbe2db2167c5
+P 2b19be7bf753c7dd12e1c3b384981a3ea1bc8145
+R 222ffce3b378b2ba18950183bb251367
 U dan
-Z 77d8992b93ad5a2a0231fb47a635b3cb
+Z b642b18410bb67d03067201d5612ecd6
diff --git a/manifest.uuid b/manifest.uuid
index f741e56cff..b6d1059b89 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-2b19be7bf753c7dd12e1c3b384981a3ea1bc8145
\ No newline at end of file
+57862efe718fdc93401998f9058511292a0e1a50
\ No newline at end of file
diff --git a/test/session1.test b/test/session1.test
index 737d796ba3..5706b77bc5 100644
--- a/test/session1.test
+++ b/test/session1.test
@@ -259,22 +259,29 @@ do_execsql_test 3.3.1 {
   CREATE TABLE t4(a, b, c, PRIMARY KEY(b, c));
   INSERT INTO t4 VALUES(1, 2, 3);
   INSERT INTO t4 VALUES(4, 5, 6);
+  INSERT INTO t4 VALUES(7, 8, 9);
+  INSERT INTO t4 VALUES(10, 11, 12);
 }
 do_db2_test 3.3.2 {
-  CREATE TABLE t4(a, b, c, PRIMARY KEY(b, c));
+  CREATE TABLE t4(a NOT NULL, b, c, PRIMARY KEY(b, c));
   INSERT INTO t4 VALUES(0, 2, 3);
   INSERT INTO t4 VALUES(4, 5, 7);
+  INSERT INTO t4 VALUES(7, 8, 9);
+  INSERT INTO t4 VALUES(10, 11, 12);
 }
-
-do_conflict_test 3.2.3 -tables t4 -sql {
+do_conflict_test 3.3.3 -tables t4 -sql {
   UPDATE t4 SET a = -1 WHERE b = 2;
+  UPDATE t4 SET a = -1 WHERE b = 5;
+  UPDATE t4 SET a = NULL WHERE c = 9;
+  UPDATE t4 SET a = 'x' WHERE b = 11;
 } -conflicts {
-  {UPDATE t4 DATA {i 1 i 2 i 3} {i -1 i 2 i 3} {i 0 i 2 i 3}}
+  {UPDATE t4 DATA {i 1 i 2 i 3} {i -1 {} {} {} {}} {i 0 i 2 i 3}}
+  {UPDATE t4 NOTFOUND {i 4 i 5 i 6} {i -1 {} {} {} {}}}
+  {UPDATE t4 CONSTRAINT {i 7 i 8 i 9} {n {} {} {} {} {}}}
 }
 
-do_db2_test 3.3.4 {
-  SELECT * FROM t4
-} {0 2 3 4 5 7}
+do_db2_test     3.3.4 { SELECT * FROM t4 } {0 2 3 4 5 7 7 8 9 x 11 12}
+do_execsql_test 3.3.5 { SELECT * FROM t4 } {-1 2 3 -1 5 6 {} 8 9 x 11 12}
 
 
 catch { db2 close }