diff --git a/ext/session/session5.test b/ext/session/session5.test
index 440a44c08b..676b2c718f 100644
--- a/ext/session/session5.test
+++ b/ext/session/session5.test
@@ -21,33 +21,46 @@ ifcapable !session {finish_test; return}
 
 set testprefix session5
 
-proc do_concat_test {tn sql1 sql2} {
-  sqlite3session S1 db main ; S1 attach *
-  sqlite3session S2 db main ; S2 attach *
+# Organization of tests:
+#
+#   session5-1.*: Simple tests to check the concat() function produces 
+#                 correct results.
+#
+#   session5-2.*: More complicated tests.
+#   
+#   session5-3.*: Schema mismatch errors.
+#
 
-  execsql $sql1
-  set C1 [S1 changeset]
-  S1 delete
+proc changeset_to_list {c} {
+  set list [list]
+  sqlite3session_foreach elem $c { lappend list $elem }
+  lsort $list
+}
 
-  sqlite3session S1 db main ; S1 attach *
+proc do_concat_test {tn args} {
 
-  execsql $sql2
-  set C2 [S1 changeset]
-  S1 delete
+  set subtest 0
+  foreach sql $args {
+    incr subtest
+    sqlite3session S db main ; S attach *
+    execsql $sql
 
-  set C3 [S2 changeset]
-  S2 delete
+    set c [S changeset]
+    if {[info commands s_prev] != ""} {
+      set c_concat [sqlite3changeset_concat $c_prev $c]
+      set c_two [s_prev changeset]
+      s_prev delete
 
-  set C4 [sqlite3changeset_concat $C1 $C2]
+      set h_concat [changeset_to_list $c_concat]
+      set h_two [changeset_to_list $c_two]
 
-  set c3 [list]
-  set c4 [list]
-  sqlite3session_foreach c $C3 { lappend c3 $c }
-  sqlite3session_foreach c $C4 { lappend c4 $c }
-  set c3 [lsort $c3]
-  set c4 [lsort $c4]
+      do_test $tn.$subtest [list set {} $h_concat] $h_two
+    }
+    set c_prev $c
+    rename S s_prev
+  }
 
-  do_test $tn [list set {} $c4] $c3
+  catch { s_prev delete }
 }
 
 do_execsql_test 1.0 {
@@ -121,4 +134,55 @@ do_concat_test 1.2.7 {
   DELETE FROM t1 WHERE a = 'I';
 }
 
+db function indirect indirect 
+proc indirect {{x -1}} {
+  S indirect $x
+  s_prev indirect $x
+}
+
+do_concat_test 2.1 {
+  CREATE TABLE abc(a, b, c PRIMARY KEY);
+  INSERT INTO abc VALUES(NULL, NULL, 1);
+  INSERT INTO abc VALUES('abcdefghijkl', NULL, 2);
+} {
+  DELETE FROM abc WHERE c = 1;
+  UPDATE abc SET c = 1 WHERE c = 2;
+} {
+  INSERT INTO abc VALUES('abcdefghijkl', NULL, 2);
+  INSERT INTO abc VALUES(1.0, 2.0, 3);
+} {
+  UPDATE abc SET a = a-1;
+} {
+  CREATE TABLE def(d, e, f, PRIMARY KEY(e, f));
+  INSERT INTO def VALUES('x', randomblob(11000), 67);
+  INSERT INTO def SELECT d, e, f+1 FROM def;
+  INSERT INTO def SELECT d, e, f+2 FROM def;
+  INSERT INTO def SELECT d, e, f+4 FROM def;
+} {
+  DELETE FROM def WHERE rowid>4;
+} { 
+  INSERT INTO def SELECT d, e, f+4 FROM def; 
+} {
+  INSERT INTO abc VALUES(22, 44, -1);
+} { 
+  UPDATE abc SET c=-2 WHERE c=-1;
+  UPDATE abc SET c=-3 WHERE c=-2;
+} {
+  UPDATE abc SET c=-4 WHERE c=-3;
+} {
+  UPDATE abc SET a=a+1 WHERE c=-3;
+  UPDATE abc SET a=a+1 WHERE c=-3;
+} {
+  UPDATE abc SET a=a+1 WHERE c=-3;
+  UPDATE abc SET a=a+1 WHERE c=-3;
+} {
+  INSERT INTO abc VALUES('one', 'two', 'three');
+} {
+  SELECT indirect(1);
+  UPDATE abc SET a='one point five' WHERE c = 'three';
+} {
+  SELECT indirect(0);
+  UPDATE abc SET a='one point six' WHERE c = 'three';
+}
+
 finish_test
diff --git a/ext/session/sqlite3session.c b/ext/session/sqlite3session.c
index 770fc13e30..f22fafa5dc 100644
--- a/ext/session/sqlite3session.c
+++ b/ext/session/sqlite3session.c
@@ -353,6 +353,20 @@ static unsigned int sessionPreupdateHash(
   return SQLITE_OK;
 }
 
+/*
+** The buffer that the argument points to contains a serialized SQL value.
+** Return the number of bytes of space occupied by the value (including
+** the type byte).
+*/
+static int sessionSerialLen(u8 *a){
+  int e = *a;
+  int n;
+  if( e==0 ) return 1;
+  if( e==SQLITE_NULL ) return 1;
+  if( e==SQLITE_INTEGER || e==SQLITE_FLOAT ) return 9;
+  return sessionVarintGet(&a[1], &n) + 1 + n;
+}
+
 /*
 ** Based on the primary key values stored in change aRecord, calculate a
 ** hash key, assuming the has table has nBucket buckets. The hash keys
@@ -369,7 +383,7 @@ static unsigned int sessionChangeHash(
   u8 *a = aRecord;                /* Used to iterate through change record */
 
   for(i=0; i<pTab->nCol; i++){
-    int eType = *a++;
+    int eType = *a;
     int isPK = pTab->abPK[i];
 
     /* It is not possible for eType to be SQLITE_NULL here. The session 
@@ -377,31 +391,29 @@ static unsigned int sessionChangeHash(
     ** primary key columns. */
     assert( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT 
          || eType==SQLITE_TEXT || eType==SQLITE_BLOB 
+         || eType==SQLITE_NULL || eType==0 
     );
+    assert( !isPK || (eType!=0 && eType!=SQLITE_NULL) );
 
-    if( isPK ) h = HASH_APPEND(h, eType);
-    if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
-      if( isPK ) h = sessionHashAppendI64(h, sessionGetI64(a));
-      a += 8;
+    if( isPK ){
+      a++;
+      h = HASH_APPEND(h, eType);
+      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+        if( isPK ) h = sessionHashAppendI64(h, sessionGetI64(a));
+        a += 8;
+      }else{
+        int n; 
+        a += sessionVarintGet(a, &n);
+        if( isPK ) h = sessionHashAppendBlob(h, n, a);
+        a += n;
+      }
     }else{
-      int n; 
-      a += sessionVarintGet(a, &n);
-      if( isPK ) h = sessionHashAppendBlob(h, n, a);
-      a += n;
+      a += sessionSerialLen(a);
     }
   }
   return (h % nBucket);
 }
 
-static int sessionSerialLen(u8 *a){
-  int e = *a;
-  int n;
-  if( e==0 ) return 1;
-  if( e==SQLITE_NULL ) return 1;
-  if( e==SQLITE_INTEGER || e==SQLITE_FLOAT ) return 9;
-  return sessionVarintGet(&a[1], &n) + 1 + n;
-}
-
 static int sessionChangeEqual(
   SessionTable *pTab,
   u8 *aLeft,                      /* Change record */
@@ -419,7 +431,7 @@ static int sessionChangeEqual(
       return 0;
     }
     a1 += n1;
-    a2 += n1;
+    a2 += n2;
   }
 
   return 1;
diff --git a/ext/session/sqlite3session.h b/ext/session/sqlite3session.h
index 10a94b927b..fcde98f842 100644
--- a/ext/session/sqlite3session.h
+++ b/ext/session/sqlite3session.h
@@ -522,10 +522,13 @@ int sqlite3changeset_invert(
   int *pnOut, void **ppOut        /* OUT: Inverse of input */
 );
 
+/*
+** CAPI3REF: Combine Two Changeset Objects
+*/
 int sqlite3changeset_concat(
-  int nLeft, void *pLeft,         /* Input changeset */
-  int nRight, void *Right,        /* Input changeset */
-  int *pnOut, void **ppOut        /* OUT: Inverse of input */
+  int nLeft, void *pLeft,         /* First input changeset */
+  int nRight, void *Right,        /* Second input changeset */
+  int *pnOut, void **ppOut        /* OUT: Output changeset */
 );
 
 /*
diff --git a/manifest b/manifest
index 4dcb9b0bb0..7b1c552c55 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Start\sadding\sthe\ssqlite3changeset_concat()\sfunction\sto\sthe\ssession\smodule.
-D 2011-04-14T11:16:21.630
+C Add\sfurther\stests\sfor\sthe\ssqlite3changeset_concat()\sfunction.\sAlso\sfixes.
+D 2011-04-14T18:01:41.789
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 7a4d9524721d40ef9ee26f93f9bd6a51dba106f2
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -103,11 +103,11 @@ F ext/session/session1.test 7a92a2a6f531aef1e9764ffb7f983fb8b315376d
 F ext/session/session2.test c3e5f78d5eb988e35cc2ba9ce3678f706283cfdb
 F ext/session/session3.test bfa2376db7cbb2ac69496f84d93a8d81b13110d3
 F ext/session/session4.test a6ed685da7a5293c5d6f99855bcf41dbc352ca84
-F ext/session/session5.test ed5025c96693d406fb13bcf330d1a962dcb68c24
+F ext/session/session5.test 9dff891440dc3a424daea914b7e08e9f137272ed
 F ext/session/session_common.tcl fb91560b6dbd086010df8b3a137a452f1ac21a28
 F ext/session/sessionfault.test 2544a2e2ecad56e3c07a32c09799871d243c114c
-F ext/session/sqlite3session.c 124ac6d43ac5820add2e736b25432c3f6b5a733a
-F ext/session/sqlite3session.h dc7c85fd27fa3a9a17b34e0951ed36cdced1bc67
+F ext/session/sqlite3session.c abf9846341847c5b81040683b143b511ee828f2e
+F ext/session/sqlite3session.h e64876b299dcd1f8c9d043d59bfe14a94ee6b2ba
 F ext/session/test_session.c f4d1dca94db71ec2177ee61eab51e718e58476d7
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
@@ -938,7 +938,7 @@ F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/split-sqlite3c.tcl d9be87f1c340285a3e081eb19b4a247981ed290c
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 83705e90a54bad462a5b7fbca70cc129998f871c
-R 2d3308935368f3ab85a5bea7204d6f97
+P 8927b2260b8d84f53776cb29e1d2fa41b6b0de0e
+R f3f9539d9ce74ceea388d1aad2d1949b
 U dan
-Z 4aed6546b387a7c5d8dbcb80467675b2
+Z 58678ea87adc6f0684f4c0fc5f0a6d31
diff --git a/manifest.uuid b/manifest.uuid
index 4733d7436b..d6d4737a85 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-8927b2260b8d84f53776cb29e1d2fa41b6b0de0e
\ No newline at end of file
+1fc3f15d88c160b45642b46d1d54c591af058ba2
\ No newline at end of file