Index: ext/session/sessioninvert.test
==================================================================
--- ext/session/sessioninvert.test
+++ ext/session/sessioninvert.test
@@ -18,11 +18,17 @@
 source $testdir/tester.tcl
 ifcapable !session {finish_test; return}
 
 set testprefix sessioninvert
 
-proc do_invert_test {tn sql} {
+proc iter_invert {C} {
+  set x [list]
+  sqlite3session_foreach -invert c $C { lappend x $c }
+  set x
+}
+
+proc do_invert_test {tn sql {iter {}}} {
 
   forcecopy test.db test.db2
   sqlite3 db2 test.db2
 
   set C [changeset_from_sql $sql]
@@ -35,10 +41,14 @@
   sqlite3changeset_apply db $I {}
   uplevel [list do_test $tn.2 [list compare_db db db2] {}]
   
   sqlite3changeset_apply_v2 -invert db3 $C {}
   uplevel [list do_test $tn.3 [list compare_db db db3] {}]
+
+  if {$iter!=""} {
+    uplevel [list do_test $tn.4 [list iter_invert $C] [list {*}$iter]]
+  }
 
   catch { db2 close }
   catch { db3 close }
 }
 
@@ -56,28 +66,48 @@
   INSERT INTO t2 SELECT * FROM t1;
 }
 
 do_invert_test 1.1 {
   INSERT INTO t1 VALUES(7, 'seven', 'vii');
+} {
+  {DELETE t1 0 X.. {i 7 t seven t vii} {}}
 }
 
 do_invert_test 1.2 {
   DELETE FROM t1 WHERE a<4;
-}
-
-do_invert_test 1.2 {
-  UPDATE t1 SET c=5;
+} {
+  {INSERT t1 0 X.. {} {i 1 t one t i}}
+  {INSERT t1 0 X.. {} {i 2 t two t ii}}
+  {INSERT t1 0 X.. {} {i 3 t three t iii}}
 }
 
 do_invert_test 1.3 {
+  UPDATE t1 SET c=5;
+} {
+  {UPDATE t1 0 X.. {i 1 {} {} i 5} {{} {} {} {} t i}}
+  {UPDATE t1 0 X.. {i 2 {} {} i 5} {{} {} {} {} t ii}}
+  {UPDATE t1 0 X.. {i 3 {} {} i 5} {{} {} {} {} t iii}}
+  {UPDATE t1 0 X.. {i 4 {} {} i 5} {{} {} {} {} t iv}}
+  {UPDATE t1 0 X.. {i 5 {} {} i 5} {{} {} {} {} t v}}
+  {UPDATE t1 0 X.. {i 6 {} {} i 5} {{} {} {} {} t vi}}
+}
+
+do_invert_test 1.4 {
   UPDATE t1 SET b = a+1 WHERE a%2;
   DELETE FROM t2;
   INSERT INTO t1 VALUES(10, 'ten', NULL);
 }
 
-do_invert_test 1.4 {
+do_invert_test 1.5 {
   UPDATE t2 SET d = d-1;
+} {
+  {UPDATE t2 0 .XX {i 2 t three t iii} {i 3 {} {} {} {}}}
+  {UPDATE t2 0 .XX {i 1 t two t ii} {i 2 {} {} {} {}}}
+  {UPDATE t2 0 .XX {i 5 t six t vi} {i 6 {} {} {} {}}}
+  {UPDATE t2 0 .XX {i 3 t four t iv} {i 4 {} {} {} {}}}
+  {UPDATE t2 0 .XX {i 0 t one t i} {i 1 {} {} {} {}}}
+  {UPDATE t2 0 .XX {i 4 t five t v} {i 5 {} {} {} {}}}
 }
 
 do_execsql_test 2.0 { 
   ANALYZE;
   PRAGMA writable_schema = 1;
@@ -88,14 +118,19 @@
   t1 sqlite_autoindex_t1_1 {6 1}
 }
 
 do_invert_test 2.1 {
   INSERT INTO sqlite_stat1 VALUES('t3', 'idx2', '1 2 3');
+} {
+  {DELETE sqlite_stat1 0 XX. {t t3 t idx2 t {1 2 3}} {}}
 }
 
 do_invert_test 2.2 {
   DELETE FROM sqlite_stat1;
+} {
+  {INSERT sqlite_stat1 0 XX. {} {t t1 t sqlite_autoindex_t1_1 t {6 1}}}
+  {INSERT sqlite_stat1 0 XX. {} {t t2 t sqlite_autoindex_t2_1 t {6 1 1}}}
 }
 
 do_invert_test 2.3 {
   UPDATE sqlite_stat1 SET stat = 'hello world';
 }
@@ -110,11 +145,15 @@
 
   list [catch { sqlite3changeset_apply_v2 -invert db2 $P {} } msg] $msg
 } {1 SQLITE_CORRUPT}
 
 do_test 3.1 {
+  list [catch { sqlite3session_foreach -invert db2 $P {} } msg] $msg
+} {1 SQLITE_CORRUPT}
+
+do_test 3.2 {
   sqlite3changeset_apply_v2 db2 $P {} 
   compare_db db db2
 } {}
 
 
 finish_test

Index: ext/session/sqlite3session.c
==================================================================
--- ext/session/sqlite3session.c
+++ ext/session/sqlite3session.c
@@ -2577,10 +2577,19 @@
   int nChangeset,                 /* Size of buffer pChangeset in bytes */
   void *pChangeset                /* Pointer to buffer containing changeset */
 ){
   return sessionChangesetStart(pp, 0, 0, nChangeset, pChangeset, 0);
 }
+int sqlite3changeset_start_v2(
+  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
+  int nChangeset,                 /* Size of buffer pChangeset in bytes */
+  void *pChangeset,               /* Pointer to buffer containing changeset */
+  int flags
+){
+  int bInvert = !!(flags & SQLITE_CHANGESETSTART_INVERT);
+  return sessionChangesetStart(pp, 0, 0, nChangeset, pChangeset, bInvert);
+}
 
 /*
 ** Streaming version of sqlite3changeset_start().
 */
 int sqlite3changeset_start_strm(
@@ -2588,10 +2597,19 @@
   int (*xInput)(void *pIn, void *pData, int *pnData),
   void *pIn
 ){
   return sessionChangesetStart(pp, xInput, pIn, 0, 0, 0);
 }
+int sqlite3changeset_start_v2_strm(
+  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int flags
+){
+  int bInvert = !!(flags & SQLITE_CHANGESETSTART_INVERT);
+  return sessionChangesetStart(pp, xInput, pIn, 0, 0, bInvert);
+}
 
 /*
 ** If the SessionInput object passed as the only argument is a streaming
 ** object and the buffer is full, discard some data to free up space.
 */

Index: ext/session/sqlite3session.h
==================================================================
--- ext/session/sqlite3session.h
+++ ext/session/sqlite3session.h
@@ -471,16 +471,42 @@
 ** an application iterates through a changeset using an iterator created by 
 ** this function, all changes that relate to a single table are visited 
 ** consecutively. There is no chance that the iterator will visit a change 
 ** the applies to table X, then one for table Y, and then later on visit 
 ** another change for table X.
+**
+** The behavior of sqlite3changeset_start_v2() and its streaming equivalent
+** may be modified by passing a combination of
+** [SQLITE_CHANGESETSTART_INVERT | supported flags] as the 4th parameter.
+**
+** Note that the sqlite3changeset_start_v2() API is still <b>experimental</b>
+** and therefore subject to change.
 */
 int sqlite3changeset_start(
   sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */
   int nChangeset,                 /* Size of changeset blob in bytes */
   void *pChangeset                /* Pointer to blob containing changeset */
 );
+int sqlite3changeset_start_v2(
+  sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */
+  int nChangeset,                 /* Size of changeset blob in bytes */
+  void *pChangeset,               /* Pointer to blob containing changeset */
+  int flags                       /* SESSION_CHANGESETSTART_* flags */
+);
+
+/*
+** CAPI3REF: Flags for sqlite3changeset_start_v2
+**
+** The following flags may passed via the 4th parameter to
+** [sqlite3changeset_start_v2] and [sqlite3changeset_start_v2_strm]:
+**
+** <dt>SQLITE_CHANGESETAPPLY_INVERT <dd>
+**   Invert the changeset while iterating through it. This is equivalent to
+**   inverting a changeset using sqlite3changeset_invert() before applying it.
+**   It is an error to specify this flag with a patchset.
+*/
+#define SQLITE_CHANGESETSTART_INVERT        0x0002
 
 
 /*
 ** CAPI3REF: Advance A Changeset Iterator
 ** METHOD: sqlite3_changeset_iter
@@ -1131,11 +1157,11 @@
     int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
     sqlite3_changeset_iter *p     /* Handle describing change and conflict */
   ),
   void *pCtx,                     /* First argument passed to xConflict */
   void **ppRebase, int *pnRebase, /* OUT: Rebase data */
-  int flags                       /* Combination of SESSION_APPLY_* flags */
+  int flags                       /* SESSION_CHANGESETAPPLY_* flags */
 );
 
 /*
 ** CAPI3REF: Flags for sqlite3changeset_apply_v2
 **
@@ -1549,10 +1575,16 @@
 );
 int sqlite3changeset_start_strm(
   sqlite3_changeset_iter **pp,
   int (*xInput)(void *pIn, void *pData, int *pnData),
   void *pIn
+);
+int sqlite3changeset_start_v2_strm(
+  sqlite3_changeset_iter **pp,
+  int (*xInput)(void *pIn, void *pData, int *pnData),
+  void *pIn,
+  int flags
 );
 int sqlite3session_changeset_strm(
   sqlite3_session *pSession,
   int (*xOutput)(void *pOut, const void *pData, int nData),
   void *pOut

Index: ext/session/test_session.c
==================================================================
--- ext/session/test_session.c
+++ ext/session/test_session.c
@@ -979,35 +979,60 @@
   int rc;
   Tcl_Obj *pVarname;
   Tcl_Obj *pCS;
   Tcl_Obj *pScript;
   int isCheckNext = 0;
+  int isInvert = 0;
 
   TestStreamInput sStr;
   memset(&sStr, 0, sizeof(sStr));
 
-  if( objc>1 ){
+  while( objc>1 ){
     char *zOpt = Tcl_GetString(objv[1]);
-    isCheckNext = (strcmp(zOpt, "-next")==0);
+    int nOpt = strlen(zOpt);
+    if( zOpt[0]!='-' ) break;
+    if( nOpt<=7 && 0==sqlite3_strnicmp(zOpt, "-invert", nOpt) ){
+      isInvert = 1;
+    }else
+    if( nOpt<=5 && 0==sqlite3_strnicmp(zOpt, "-next", nOpt) ){
+      isCheckNext = 1;
+    }else{
+      break;
+    }
+    objv++;
+    objc--;
   }
-  if( objc!=4+isCheckNext ){
-    Tcl_WrongNumArgs(interp, 1, objv, "?-next? VARNAME CHANGESET SCRIPT");
+  if( objc!=4 ){
+    Tcl_WrongNumArgs(
+        interp, 1, objv, "?-next? ?-invert? VARNAME CHANGESET SCRIPT");
     return TCL_ERROR;
   }
 
-  pVarname = objv[1+isCheckNext];
-  pCS = objv[2+isCheckNext];
-  pScript = objv[3+isCheckNext];
+  pVarname = objv[1];
+  pCS = objv[2];
+  pScript = objv[3];
 
   pChangeset = (void *)Tcl_GetByteArrayFromObj(pCS, &nChangeset);
   sStr.nStream = test_tcl_integer(interp, SESSION_STREAM_TCL_VAR);
-  if( sStr.nStream==0 ){
-    rc = sqlite3changeset_start(&pIter, nChangeset, pChangeset);
+  if( isInvert ){
+    int f = SQLITE_CHANGESETSTART_INVERT;
+    if( sStr.nStream==0 ){
+      rc = sqlite3changeset_start_v2(&pIter, nChangeset, pChangeset, f);
+    }else{
+      void *pCtx = (void*)&sStr;
+      sStr.aData = (unsigned char*)pChangeset;
+      sStr.nData = nChangeset;
+      rc = sqlite3changeset_start_v2_strm(&pIter, testStreamInput, pCtx, f);
+    }
   }else{
-    sStr.aData = (unsigned char*)pChangeset;
-    sStr.nData = nChangeset;
-    rc = sqlite3changeset_start_strm(&pIter, testStreamInput, (void*)&sStr);
+    if( sStr.nStream==0 ){
+      rc = sqlite3changeset_start(&pIter, nChangeset, pChangeset);
+    }else{
+      sStr.aData = (unsigned char*)pChangeset;
+      sStr.nData = nChangeset;
+      rc = sqlite3changeset_start_strm(&pIter, testStreamInput, (void*)&sStr);
+    }
   }
   if( rc!=SQLITE_OK ){
     return test_session_error(interp, rc, 0);
   }