Add new sessions API sqlite3changegroup_add_change().

FossilOrigin-Name: 5eaab43ce48bb8d710f784ecd6aa9a4b3e708b44b0f7e49daf66a3f8bc2b9873

6 files changed, 489 insertions, 166 deletions

diff --git a/ext/session/sessionchange.test b/ext/session/sessionchange.test
new file mode 100644
index 000000000..c1c28622e
--- /dev/null
+++ b/ext/session/sessionchange.test
@@ -0,0 +1,101 @@
+# 2011 March 07
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.
+#
+
+if {![info exists testdir]} {
+  set testdir [file join [file dirname [info script]] .. .. test]
+} 
+source [file join [file dirname [info script]] session_common.tcl]
+source $testdir/tester.tcl
+ifcapable !session {finish_test; return}
+
+set testprefix sessionchange
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
+}
+
+do_test 1.1 { 
+  set C [changeset_from_sql {
+    INSERT INTO t1 VALUES(1, 2, 3);
+    INSERT INTO t1 VALUES(10, 20, 30);
+  }]
+
+  set res [list]
+  set iter [sqlite3changeset_start $C]
+  while {[$iter next]=="SQLITE_ROW"} {
+    lappend res [$iter data]
+  }
+  $iter finalize
+
+  set res
+} [list \
+  {INSERT t1 0 X.. {} {i 10 i 20 i 30}}  \
+  {INSERT t1 0 X.. {} {i 1 i 2 i 3}}     \
+]
+
+
+do_test 1.2 {
+  sqlite3changegroup grp
+  set iter [sqlite3changeset_start $C]
+  while {[$iter next]=="SQLITE_ROW"} {
+    grp add_change $iter
+  }
+  $iter finalize
+
+  set res [list]
+  grp output
+  sqlite3session_foreach c [grp output] { lappend res $c }
+  grp delete
+  set res
+} [list \
+  {INSERT t1 0 X.. {} {i 10 i 20 i 30}}  \
+  {INSERT t1 0 X.. {} {i 1 i 2 i 3}}     \
+]
+
+do_test 1.3.1 {
+  set iter [sqlite3changeset_start $C]
+  sqlite3changegroup grp
+  list [catch { grp add_change $iter } msg] $msg
+} {1 SQLITE_ERROR}
+do_test 1.3.2 {
+  while {[$iter next]=="SQLITE_ROW"} { }
+  list [catch { grp add_change $iter } msg] $msg
+} {1 SQLITE_ERROR}
+grp delete
+$iter finalize
+
+do_test 1.4 {
+  set res [list]
+  set iter [sqlite3changeset_start -invert $C]
+  while {[$iter next]=="SQLITE_ROW"} {
+    lappend res [$iter data]
+  }
+  $iter finalize
+  set res
+} [list \
+  {DELETE t1 0 X.. {i 10 i 20 i 30} {}}   \
+  {DELETE t1 0 X.. {i 1 i 2 i 3} {}}      \
+]
+
+do_test 1.5 {
+  sqlite3changegroup grp
+  set iter [sqlite3changeset_start -invert $C]
+  $iter next
+  list [catch { grp add_change $iter } msg] $msg
+} {1 SQLITE_ERROR}
+$iter finalize
+grp delete
+
+
+
+finish_test
diff --git a/ext/session/sqlite3session.c b/ext/session/sqlite3session.c
index acb945194..7a8132bfa 100644
--- a/ext/session/sqlite3session.c
+++ b/ext/session/sqlite3session.c
@@ -3685,14 +3685,14 @@ static int sessionChangesetNextOne(
   p->rc = sessionInputBuffer(&p->in, 2);
   if( p->rc!=SQLITE_OK ) return p->rc;
 
+  sessionDiscardData(&p->in);
+  p->in.iCurrent = p->in.iNext;
+
   /* If the iterator is already at the end of the changeset, return DONE. */
   if( p->in.iNext>=p->in.nData ){
     return SQLITE_DONE;
   }
 
-  sessionDiscardData(&p->in);
-  p->in.iCurrent = p->in.iNext;
-
   op = p->in.aData[p->in.iNext++];
   while( op=='T' || op=='P' ){
     if( pbNew ) *pbNew = 1;
@@ -5427,6 +5427,7 @@ struct sqlite3_changegroup {
   int rc;                         /* Error code */
   int bPatch;                     /* True to accumulate patchsets */
   SessionTable *pList;            /* List of tables in current patch */
+  SessionBuffer rec;
 
   sqlite3 *db;                    /* Configured by changegroup_schema() */
   char *zDb;                      /* Configured by changegroup_schema() */
@@ -5725,108 +5726,128 @@ static int sessionChangesetExtendRecord(
 }
 
 /*
-** Add all changes in the changeset traversed by the iterator passed as
-** the first argument to the changegroup hash tables.
+** Locate or create a SessionTable object that may be used to add the
+** change currently pointed to by iterator pIter to changegroup pGrp.
+** If successful, set output variable (*ppTab) to point to the table
+** object and return SQLITE_OK. Otherwise, if some error occurs, return
+** an SQLite error code and leave (*ppTab) set to NULL.
 */
-static int sessionChangesetToHash(
-  sqlite3_changeset_iter *pIter,   /* Iterator to read from */
-  sqlite3_changegroup *pGrp,       /* Changegroup object to add changeset to */
-  int bRebase                      /* True if hash table is for rebasing */
+static int sessionChangesetFindTable(
+  sqlite3_changegroup *pGrp, 
+  const char *zTab, 
+  sqlite3_changeset_iter *pIter, 
+  SessionTable **ppTab
 ){
-  u8 *aRec;
-  int nRec;
   int rc = SQLITE_OK;
   SessionTable *pTab = 0;
-  SessionBuffer rec = {0, 0, 0};
+  int nTab = (int)strlen(zTab);
+  u8 *abPK = 0;
+  int nCol = 0;
 
-  while( SQLITE_ROW==sessionChangesetNext(pIter, &aRec, &nRec, 0) ){
-    const char *zNew;
-    int nCol;
-    int op;
-    int iHash;
-    int bIndirect;
-    SessionChange *pChange;
-    SessionChange *pExist = 0;
-    SessionChange **pp;
-
-    /* Ensure that only changesets, or only patchsets, but not a mixture
-    ** of both, are being combined. It is an error to try to combine a
-    ** changeset and a patchset.  */
-    if( pGrp->pList==0 ){
-      pGrp->bPatch = pIter->bPatchset;
-    }else if( pIter->bPatchset!=pGrp->bPatch ){
-      rc = SQLITE_ERROR;
-      break;
-    }
+  *ppTab = 0;
+  sqlite3changeset_pk(pIter, &abPK, &nCol);
 
-    sqlite3changeset_op(pIter, &zNew, &nCol, &op, &bIndirect);
-    if( !pTab || sqlite3_stricmp(zNew, pTab->zName) ){
-      /* Search the list for a matching table */
-      int nNew = (int)strlen(zNew);
-      u8 *abPK;
+  /* Search the list for an existing table */
+  for(pTab = pGrp->pList; pTab; pTab=pTab->pNext){
+    if( 0==sqlite3_strnicmp(pTab->zName, zTab, nTab+1) ) break;
+  }
 
-      sqlite3changeset_pk(pIter, &abPK, 0);
-      for(pTab = pGrp->pList; pTab; pTab=pTab->pNext){
-        if( 0==sqlite3_strnicmp(pTab->zName, zNew, nNew+1) ) break;
+  /* If one was not found above, create a new table now */
+  if( !pTab ){
+    SessionTable **ppNew;
+
+    pTab = sqlite3_malloc64(sizeof(SessionTable) + nCol + nTab+1);
+    if( !pTab ){
+      return SQLITE_NOMEM;
+    }
+    memset(pTab, 0, sizeof(SessionTable));
+    pTab->nCol = nCol;
+    pTab->abPK = (u8*)&pTab[1];
+    memcpy(pTab->abPK, abPK, nCol);
+    pTab->zName = (char*)&pTab->abPK[nCol];
+    memcpy(pTab->zName, zTab, nTab+1);
+
+    if( pGrp->db ){
+      pTab->nCol = 0;
+      rc = sessionInitTable(0, pTab, pGrp->db, pGrp->zDb);
+      if( rc ){
+        assert( pTab->azCol==0 );
+        sqlite3_free(pTab);
+        return rc;
       }
-      if( !pTab ){
-        SessionTable **ppTab;
+    }
 
-        pTab = sqlite3_malloc64(sizeof(SessionTable) + nCol + nNew+1);
-        if( !pTab ){
-          rc = SQLITE_NOMEM;
-          break;
-        }
-        memset(pTab, 0, sizeof(SessionTable));
-        pTab->nCol = nCol;
-        pTab->abPK = (u8*)&pTab[1];
-        memcpy(pTab->abPK, abPK, nCol);
-        pTab->zName = (char*)&pTab->abPK[nCol];
-        memcpy(pTab->zName, zNew, nNew+1);
-
-        if( pGrp->db ){
-          pTab->nCol = 0;
-          rc = sessionInitTable(0, pTab, pGrp->db, pGrp->zDb);
-          if( rc ){
-            assert( pTab->azCol==0 );
-            sqlite3_free(pTab);
-            break;
-          }
-        }
+    /* The new object must be linked on to the end of the list, not
+    ** simply added to the start of it. This is to ensure that the
+    ** tables within the output of sqlite3changegroup_output() are in 
+    ** the right order.  */
+    for(ppNew=&pGrp->pList; *ppNew; ppNew=&(*ppNew)->pNext);
+    *ppNew = pTab;
+  }
 
-        /* The new object must be linked on to the end of the list, not
-        ** simply added to the start of it. This is to ensure that the
-        ** tables within the output of sqlite3changegroup_output() are in 
-        ** the right order.  */
-        for(ppTab=&pGrp->pList; *ppTab; ppTab=&(*ppTab)->pNext);
-        *ppTab = pTab;
-      }
+  /* Check that the table is compatible. */
+  if( !sessionChangesetCheckCompat(pTab, nCol, abPK) ){
+    rc = SQLITE_SCHEMA;
+  }
 
-      if( !sessionChangesetCheckCompat(pTab, nCol, abPK) ){
-        rc = SQLITE_SCHEMA;
-        break;
-      }
-    }
+  *ppTab = pTab;
+  return rc;
+}
 
-    if( nCol<pTab->nCol ){
-      assert( pGrp->db );
-      rc = sessionChangesetExtendRecord(pGrp, pTab, nCol, op, aRec, nRec, &rec);
-      if( rc ) break;
-      aRec = rec.aBuf;
-      nRec = rec.nBuf;
-    }
+/*
+** Add the change currently indicated by iterator pIter to the hash table
+** belonging to changegroup pGrp.
+*/
+static int sessionOneChangeToHash(
+  sqlite3_changegroup *pGrp,
+  sqlite3_changeset_iter *pIter,
+  int bRebase
+){
+  int rc = SQLITE_OK;
+  int nCol = 0;
+  int op = 0;
+  int iHash = 0;
+  int bIndirect = 0;
+  SessionChange *pChange = 0;
+  SessionChange *pExist = 0;
+  SessionChange **pp = 0;
+  SessionTable *pTab = 0;
+  u8 *aRec = &pIter->in.aData[pIter->in.iCurrent + 2];
+  int nRec = (pIter->in.iNext - pIter->in.iCurrent) - 2;
 
-    if( sessionGrowHash(0, pIter->bPatchset, pTab) ){
-      rc = SQLITE_NOMEM;
-      break;
-    }
+  /* Ensure that only changesets, or only patchsets, but not a mixture
+  ** of both, are being combined. It is an error to try to combine a
+  ** changeset and a patchset.  */
+  if( pGrp->pList==0 ){
+    pGrp->bPatch = pIter->bPatchset;
+  }else if( pIter->bPatchset!=pGrp->bPatch ){
+    rc = SQLITE_ERROR;
+  }
+
+  if( rc==SQLITE_OK ){
+    const char *zTab = 0;
+    sqlite3changeset_op(pIter, &zTab, &nCol, &op, &bIndirect);
+    rc = sessionChangesetFindTable(pGrp, zTab, pIter, &pTab);
+  }
+
+  if( rc==SQLITE_OK && nCol<pTab->nCol ){
+    SessionBuffer *pBuf = &pGrp->rec;
+    rc = sessionChangesetExtendRecord(pGrp, pTab, nCol, op, aRec, nRec, pBuf);
+    aRec = pBuf->aBuf;
+    nRec = pBuf->nBuf;
+    assert( pGrp->db );
+  }
+
+  if( rc==SQLITE_OK && sessionGrowHash(0, pIter->bPatchset, pTab) ){
+    rc = SQLITE_NOMEM;
+  }
+
+  if( rc==SQLITE_OK ){
+    /* Search for existing entry. If found, remove it from the hash table. 
+    ** Code below may link it back in.  */
     iHash = sessionChangeHash(
         pTab, (pIter->bPatchset && op==SQLITE_DELETE), aRec, pTab->nChange
     );
-
-    /* Search for existing entry. If found, remove it from the hash table. 
-    ** Code below may link it back in.
-    */
     for(pp=&pTab->apChange[iHash]; *pp; pp=&(*pp)->pNext){
       int bPkOnly1 = 0;
       int bPkOnly2 = 0;
@@ -5841,19 +5862,41 @@ static int sessionChangesetToHash(
         break;
       }
     }
+  }
 
+  if( rc==SQLITE_OK ){
     rc = sessionChangeMerge(pTab, bRebase, 
         pIter->bPatchset, pExist, op, bIndirect, aRec, nRec, &pChange
     );
-    if( rc ) break;
-    if( pChange ){
-      pChange->pNext = pTab->apChange[iHash];
-      pTab->apChange[iHash] = pChange;
-      pTab->nEntry++;
-    }
+  }
+  if( rc==SQLITE_OK && pChange ){
+    pChange->pNext = pTab->apChange[iHash];
+    pTab->apChange[iHash] = pChange;
+    pTab->nEntry++;
+  }
+
+  if( rc==SQLITE_OK ) rc = pIter->rc;
+  return rc;
+}
+
+/*
+** Add all changes in the changeset traversed by the iterator passed as
+** the first argument to the changegroup hash tables.
+*/
+static int sessionChangesetToHash(
+  sqlite3_changeset_iter *pIter,   /* Iterator to read from */
+  sqlite3_changegroup *pGrp,       /* Changegroup object to add changeset to */
+  int bRebase                      /* True if hash table is for rebasing */
+){
+  u8 *aRec;
+  int nRec;
+  int rc = SQLITE_OK;
+
+  while( SQLITE_ROW==(sessionChangesetNext(pIter, &aRec, &nRec, 0)) ){
+    rc = sessionOneChangeToHash(pGrp, pIter, bRebase);
+    if( rc!=SQLITE_OK ) break;
   }
 
-  sqlite3_free(rec.aBuf);
   if( rc==SQLITE_OK ) rc = pIter->rc;
   return rc;
 }
@@ -5982,6 +6025,23 @@ int sqlite3changegroup_add(sqlite3_changegroup *pGrp, int nData, void *pData){
 }
 
 /*
+** Add a single change to a changeset-group.
+*/
+int sqlite3changegroup_add_change(
+  sqlite3_changegroup *pGrp,
+  sqlite3_changeset_iter *pIter
+){
+  if( pIter->in.iCurrent==pIter->in.iNext 
+   || pIter->rc!=SQLITE_OK 
+   || pIter->bInvert
+  ){
+    /* Iterator does not point to any valid entry or is an INVERT iterator. */
+    return SQLITE_ERROR;
+  }
+  return sessionOneChangeToHash(pGrp, pIter, 0);
+}
+
+/*
 ** Obtain a buffer containing a changeset representing the concatenation
 ** of all changesets added to the group so far.
 */
@@ -6030,6 +6090,7 @@ void sqlite3changegroup_delete(sqlite3_changegroup *pGrp){
   if( pGrp ){
     sqlite3_free(pGrp->zDb);
     sessionDeleteTable(0, pGrp->pList);
+    sqlite3_free(pGrp->rec.aBuf);
     sqlite3_free(pGrp);
   }
 }
@@ -6431,6 +6492,7 @@ int sqlite3rebaser_rebase_strm(
 void sqlite3rebaser_delete(sqlite3_rebaser *p){
   if( p ){
     sessionDeleteTable(0, p->grp.pList);
+    sqlite3_free(p->grp.rec.aBuf);
     sqlite3_free(p);
   }
 }
diff --git a/ext/session/sqlite3session.h b/ext/session/sqlite3session.h
index 160ea8786..aa4862eb2 100644
--- a/ext/session/sqlite3session.h
+++ b/ext/session/sqlite3session.h
@@ -1058,6 +1058,30 @@ int sqlite3changegroup_schema(sqlite3_changegroup*, sqlite3*, const char *zDb);
 int sqlite3changegroup_add(sqlite3_changegroup*, int nData, void *pData);
 
 /*
+** CAPI3REF: Add A Single Change To A Changegroup
+** METHOD: sqlite3_changegroup
+**
+** This function adds the single change currently indicated by the iterator
+** passed as the second argument to the changegroup object. The rules for
+** adding the change are just as described for [sqlite3_changegroup_add()].
+**
+** If the change is successfully added to the changegroup, SQLITE_OK is
+** returned. Otherwise, an SQLite error code is returned.
+**
+** The iterator must point to a valid entry when this function is called.
+** If it does not, SQLITE_ERROR is returned and no change is added to the
+** changegroup. Additionally, the iterator must not have been opened with
+** the SQLITE_CHANGESETAPPLY_INVERT flag. In this case SQLITE_ERROR is also
+** returned.
+*/
+int sqlite3changegroup_add_change(
+  sqlite3_changegroup*,
+  sqlite3_changeset_iter*
+);
+
+
+
+/*
 ** CAPI3REF: Obtain A Composite Changeset From A Changegroup
 ** METHOD: sqlite3_changegroup
 **
diff --git a/ext/session/test_session.c b/ext/session/test_session.c
index af42351ba..00c3c2506 100644
--- a/ext/session/test_session.c
+++ b/ext/session/test_session.c
@@ -1038,6 +1038,64 @@ static int SQLITE_TCLAPI test_sqlite3changeset_concat(
   return rc;
 }
 
+static Tcl_Obj *testIterData(sqlite3_changeset_iter *pIter){
+  Tcl_Obj *pVar = 0;
+  int nCol;                       /* Number of columns in table */
+  int nCol2;                      /* Number of columns in table */
+  int op;                         /* SQLITE_INSERT, UPDATE or DELETE */
+  const char *zTab;               /* Name of table change applies to */
+  Tcl_Obj *pOld;                  /* Vector of old.* values */
+  Tcl_Obj *pNew;                  /* Vector of new.* values */
+  int bIndirect;
+    
+  char *zPK;
+  unsigned char *abPK;
+  int i;
+
+  sqlite3changeset_op(pIter, &zTab, &nCol, &op, &bIndirect);
+  pVar = Tcl_NewObj();
+
+  Tcl_ListObjAppendElement(0, pVar, Tcl_NewStringObj(
+        op==SQLITE_INSERT ? "INSERT" :
+        op==SQLITE_UPDATE ? "UPDATE" : 
+        "DELETE", -1
+  ));
+
+  Tcl_ListObjAppendElement(0, pVar, Tcl_NewStringObj(zTab, -1));
+  Tcl_ListObjAppendElement(0, pVar, Tcl_NewBooleanObj(bIndirect));
+
+  zPK = ckalloc(nCol+1);
+  memset(zPK, 0, nCol+1);
+  sqlite3changeset_pk(pIter, &abPK, &nCol2);
+  assert( nCol==nCol2 );
+  for(i=0; i<nCol; i++){
+    zPK[i] = (abPK[i] ? 'X' : '.');
+  }
+  Tcl_ListObjAppendElement(0, pVar, Tcl_NewStringObj(zPK, -1));
+  ckfree(zPK);
+
+  pOld = Tcl_NewObj();
+  if( op!=SQLITE_INSERT ){
+    for(i=0; i<nCol; i++){
+      sqlite3_value *pVal;
+      sqlite3changeset_old(pIter, i, &pVal);
+      test_append_value(pOld, pVal);
+    }
+  }
+  pNew = Tcl_NewObj();
+  if( op!=SQLITE_DELETE ){
+    for(i=0; i<nCol; i++){
+      sqlite3_value *pVal;
+      sqlite3changeset_new(pIter, i, &pVal);
+      test_append_value(pNew, pVal);
+    }
+  }
+  Tcl_ListObjAppendElement(0, pVar, pOld);
+  Tcl_ListObjAppendElement(0, pVar, pNew);
+
+  return pVar;
+}
+
 /*
 ** sqlite3session_foreach VARNAME CHANGESET SCRIPT
 */
@@ -1111,67 +1169,8 @@ static int SQLITE_TCLAPI test_sqlite3session_foreach(
   }
 
   while( SQLITE_ROW==sqlite3changeset_next(pIter) ){
-    int nCol;                     /* Number of columns in table */
-    int nCol2;                    /* Number of columns in table */
-    int op;                       /* SQLITE_INSERT, UPDATE or DELETE */
-    const char *zTab;             /* Name of table change applies to */
-    Tcl_Obj *pVar;                /* Tcl value to set $VARNAME to */
-    Tcl_Obj *pOld;                /* Vector of old.* values */
-    Tcl_Obj *pNew;                /* Vector of new.* values */
-    int bIndirect;
-
-    char *zPK;
-    unsigned char *abPK;
-    int i;
-
-    /* Test that _fk_conflicts() returns SQLITE_MISUSE if called on this
-    ** iterator. */
-    int nDummy;
-    if( SQLITE_MISUSE!=sqlite3changeset_fk_conflicts(pIter, &nDummy) ){
-      sqlite3changeset_finalize(pIter);
-      return TCL_ERROR;
-    }
-
-    sqlite3changeset_op(pIter, &zTab, &nCol, &op, &bIndirect);
-    pVar = Tcl_NewObj();
-    Tcl_ListObjAppendElement(0, pVar, Tcl_NewStringObj(
-          op==SQLITE_INSERT ? "INSERT" :
-          op==SQLITE_UPDATE ? "UPDATE" : 
-          "DELETE", -1
-    ));
-
-    Tcl_ListObjAppendElement(0, pVar, Tcl_NewStringObj(zTab, -1));
-    Tcl_ListObjAppendElement(0, pVar, Tcl_NewBooleanObj(bIndirect));
-
-    zPK = ckalloc(nCol+1);
-    memset(zPK, 0, nCol+1);
-    sqlite3changeset_pk(pIter, &abPK, &nCol2);
-    assert( nCol==nCol2 );
-    for(i=0; i<nCol; i++){
-      zPK[i] = (abPK[i] ? 'X' : '.');
-    }
-    Tcl_ListObjAppendElement(0, pVar, Tcl_NewStringObj(zPK, -1));
-    ckfree(zPK);
-
-    pOld = Tcl_NewObj();
-    if( op!=SQLITE_INSERT ){
-      for(i=0; i<nCol; i++){
-        sqlite3_value *pVal;
-        sqlite3changeset_old(pIter, i, &pVal);
-        test_append_value(pOld, pVal);
-      }
-    }
-    pNew = Tcl_NewObj();
-    if( op!=SQLITE_DELETE ){
-      for(i=0; i<nCol; i++){
-        sqlite3_value *pVal;
-        sqlite3changeset_new(pIter, i, &pVal);
-        test_append_value(pNew, pVal);
-      }
-    }
-    Tcl_ListObjAppendElement(0, pVar, pOld);
-    Tcl_ListObjAppendElement(0, pVar, pNew);
-
+    Tcl_Obj *pVar = 0;            /* Tcl value to set $VARNAME to */
+    pVar = testIterData(pIter);
     Tcl_ObjSetVar2(interp, pVarname, 0, pVar, 0);
     rc = Tcl_EvalObjEx(interp, pScript, 0);
     if( rc!=TCL_OK && rc!=TCL_CONTINUE ){
@@ -1459,6 +1458,12 @@ struct TestChangegroup {
   sqlite3_changegroup *pGrp;
 };
 
+typedef struct TestChangeIter TestChangeIter;
+struct TestChangeIter {
+  sqlite3_changeset_iter *pIter;
+};
+
+
 /*
 ** Destructor for Tcl changegroup command object.
 */
@@ -1491,6 +1496,7 @@ static int SQLITE_TCLAPI test_changegroup_cmd(
     { "add",          1, "CHANGESET",  }, /* 1 */
     { "output",       0, "",           }, /* 2 */
     { "delete",       0, "",           }, /* 3 */
+    { "add_change",   1, "ITERATOR",   }, /* 4 */
     { 0 }
   };
   int rc = TCL_OK;
@@ -1542,6 +1548,24 @@ static int SQLITE_TCLAPI test_changegroup_cmd(
       break;
     };
 
+    case 4: {      /* add_change */
+      Tcl_CmdInfo cmdInfo;            /* Database Tcl command (objv[2]) info */
+      TestChangeIter *pIter = 0;
+      const char *zIter = Tcl_GetString(objv[2]);
+      if( 0==Tcl_GetCommandInfo(interp, zIter, &cmdInfo) ){
+        Tcl_AppendResult(interp, "no such iter: ", Tcl_GetString(objv[2]), 0);
+        return TCL_ERROR;
+      }
+
+      pIter = (struct TestChangeIter*)cmdInfo.objClientData;
+
+      rc = sqlite3changegroup_add_change(p->pGrp, pIter->pIter);
+      if( rc!=SQLITE_OK ){
+        rc = test_session_error(interp, rc, 0);
+      }
+      break;
+    };
+
     default: {     /* delete */
       assert( iSub==3 );
       Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
@@ -1585,6 +1609,115 @@ static int SQLITE_TCLAPI test_sqlite3changegroup(
   return TCL_OK;
 }
 
+extern const char *sqlite3ErrName(int);
+
+/*
+** Destructor for Tcl iterator command object.
+*/
+static void test_iter_del(void *clientData){
+  TestChangeIter *p = (TestChangeIter*)clientData;
+  sqlite3changeset_finalize(p->pIter);
+  ckfree(p);
+}
+
+static int SQLITE_TCLAPI test_iter_cmd(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  static const char *aSub[] = {
+    "next",        /* 0 */
+    "data",        /* 1 */
+    "finalize",    /* 2 */
+    0
+  };
+  int iSub = 0;
+
+  TestChangeIter *p = (TestChangeIter*)clientData;
+  int rc = SQLITE_OK;
+
+  if( objc<2 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "CMD");
+    return TCL_ERROR;
+  }
+
+  if( Tcl_GetIndexFromObj(interp, objv[1], aSub, "sub-command", 0, &iSub) ){
+    return TCL_ERROR;
+  }
+  switch( iSub ){
+    case 0:
+      rc = sqlite3changeset_next(p->pIter);
+      Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+      break;
+    case 1:
+      Tcl_SetObjResult(interp, testIterData(p->pIter));
+      break;
+    case 2:
+      rc = sqlite3changeset_finalize(p->pIter);
+      p->pIter = 0;
+      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
+      Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+      break;
+    default:
+      assert( 0 );
+      break;
+  }
+
+  return TCL_OK;
+}
+
+/*
+** Tclcmd:  sqlite3changeset_start ?-invert? CHANGESET
+*/
+static int SQLITE_TCLAPI test_sqlite3changeset_start(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  int isInvert = 0;
+  void *pChangeset = 0;           /* Buffer containing changeset */
+  int nChangeset = 0;             /* Size of buffer aChangeset in bytes */
+  TestChangeIter *pNew = 0;
+  sqlite3_changeset_iter *pIter = 0;
+  int flags = 0;
+  int rc = SQLITE_OK;
+
+  static int iCmd = 1;
+  char zCmd[64];
+
+  if( objc==3 ){
+    int n = 0;
+    const char *z = Tcl_GetStringFromObj(objv[1], &n);
+    isInvert = (n>=2 && sqlite3_strnicmp(z, "-invert", n)==0);
+  }
+
+  if( objc!=2 && (objc!=3 || !isInvert) ){
+    Tcl_WrongNumArgs(interp, 1, objv, "?-invert? CHANGESET");
+    return TCL_ERROR;
+  }
+
+  flags = isInvert ? SQLITE_CHANGESETSTART_INVERT : 0;
+  pChangeset = (void *)Tcl_GetByteArrayFromObj(objv[objc-1], &nChangeset);
+  rc = sqlite3changeset_start_v2(&pIter, nChangeset, pChangeset, flags);
+  if( rc!=SQLITE_OK ){
+    char *zErr = sqlite3_mprintf(
+        "error in sqlite3changeset_start_v2() - %d", rc
+    );
+    Tcl_AppendResult(interp, zErr, (char*)0);
+    return TCL_ERROR;
+  }
+
+  pNew = (TestChangeIter*)ckalloc(sizeof(TestChangeIter));
+  pNew->pIter = pIter;
+
+  sprintf(zCmd, "csiter%d", iCmd++);
+  Tcl_CreateObjCommand(interp, zCmd, test_iter_cmd, (void*)pNew, test_iter_del);
+  Tcl_SetObjResult(interp, Tcl_NewStringObj(zCmd, -1));
+  return TCL_OK;
+}
+
 int TestSession_Init(Tcl_Interp *interp){
   struct Cmd {
     const char *zCmd;
@@ -1592,6 +1725,7 @@ int TestSession_Init(Tcl_Interp *interp){
   } aCmd[] = {
     { "sqlite3session", test_sqlite3session },
     { "sqlite3changegroup", test_sqlite3changegroup },
+    { "sqlite3changeset_start", test_sqlite3changeset_start },
     { "sqlite3session_foreach", test_sqlite3session_foreach },
     { "sqlite3changeset_invert", test_sqlite3changeset_invert },
     { "sqlite3changeset_concat", test_sqlite3changeset_concat },
diff --git a/manifest b/manifest
index 1c056496d..f7d7702ed 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sproblem\sin\ssqlar_uncompress()\swhen\sbeing\sused\sto\sextract\ssymbolic\slinks.
-D 2024-05-06T11:27:47.649
+C Add\snew\ssessions\sAPI\ssqlite3changegroup_add_change().
+D 2024-05-06T17:55:19.315
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -567,6 +567,7 @@ F ext/session/session_speed_test.c dcf0ef58d76b70c8fbd9eab3be77cf9deb8bc1638fed8
 F ext/session/sessionalter.test 460bdac2832a550519f6bc32e5db2c0cee94f335870aaf25a3a403a81ab20e17
 F ext/session/sessionat.test 00c8badb35e43a2f12a716d2734a44d614ff62361979b6b85419035bc04b45ee
 F ext/session/sessionbig.test 47c381e7acfabeef17d98519a3080d69151723354d220afa2053852182ca7adf
+F ext/session/sessionchange.test 77c4702050f24270b58070e2cf01c95c3d232a3ef164b70f31974b386ce69903
 F ext/session/sessionconflict.test 28890457bb90457be772d3067cdb5f78db9b51d997e4f3d09f22cddc9be80a38
 F ext/session/sessiondiff.test ad13dd65664bae26744e1f18eb3cbd5588349b7e9118851d8f9364248d67bcec
 F ext/session/sessionfault.test 573bf027fb870d57bd4e7cf50822a3e4b17b2b923407438747aaa918dec57a09
@@ -582,9 +583,9 @@ F ext/session/sessionrowid.test 85187c2f1b38861a5844868126f69f9ec62223a03449a98a
 F ext/session/sessionsize.test 8fcf4685993c3dbaa46a24183940ab9f5aa9ed0d23e5fb63bfffbdb56134b795
 F ext/session/sessionstat1.test 5e718d5888c0c49bbb33a7a4f816366db85f59f6a4f97544a806421b85dc2dec
 F ext/session/sessionwor.test 6fd9a2256442cebde5b2284936ae9e0d54bde692d0f5fd009ecef8511f4cf3fc
-F ext/session/sqlite3session.c 829d468f0f3d2710aace56b0116a7ca3f414683ce78e3125ae5e21547a895078
-F ext/session/sqlite3session.h 4cf19a51975746d7cff2fdd74db8b769c570958e1c3639ac150d824ac1553b3e
-F ext/session/test_session.c 7b94ad945cd4afe6c73ee935aeb3d44b4446186e1729362af616c7695a5283d9
+F ext/session/sqlite3session.c c7473aafbd88f796391a8c25aa90975a8f3729ab7f4f8cf74ab9d3b014e10abe
+F ext/session/sqlite3session.h c02e7bbeb38647436fa7d6f364ffe90ac61b8ba5a28f0c04b22a23887baab6cb
+F ext/session/test_session.c 8bcc857125372e640f75ab63b4188080f9bbab92b65f86dfd160721c574b2044
 F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
 F ext/userauth/user-auth.txt ca7e9ee82ca4e1c1744295f8184dd70edfae1992865d26c64303f539eb6c084c
 F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865f002fc80cb
@@ -2188,8 +2189,9 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 9bdf73a8d4a3b4a72f2882252f9ed29a6f1a26d3f50c071f27455bcf10458c4b
-R c4e317266c51f659c5ce93f052688c23
+P 4d90c3f179a3d7355b6b0202faf56f0be4be56986920576e528208cb84daa4af 49f84878e21f85d44d8429cdc2908f87383e59737e1af3fdbccf0c276d883567
+R 17b8f244002104b13ac86f24d06a1235
+T +closed 49f84878e21f85d44d8429cdc2908f87383e59737e1af3fdbccf0c276d883567
 U dan
-Z d759657d9ef1cadf5eb299f7ac2ab3b0
+Z ea504d9f33b8a329c60b503f8918f722
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 3cdac355c..048c98751 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-4d90c3f179a3d7355b6b0202faf56f0be4be56986920576e528208cb84daa4af
\ No newline at end of file
+5eaab43ce48bb8d710f784ecd6aa9a4b3e708b44b0f7e49daf66a3f8bc2b9873
\ No newline at end of file