fix a TDB balance bug

source/libs/tdb/src/db/tdbBtree.c

@@ -582,14 +582,14 @@ static int tdbBtreeBalanceNonRoot(SBTree *pBt, SPage *pParent, int idx, TXN *pTx
       SCell *pCell;
       int    szLCell, szRCell;
 
+      // balance page (iNew) and (iNew-1)
       for (;;) {
         pCell = tdbPageGetCell(pOlds[infoNews[iNew - 1].iPage], infoNews[iNew - 1].oIdx);
 
-        if (childNotLeaf) {
-          szLCell = szRCell = tdbBtreeCellSize(pOlds[infoNews[iNew - 1].iPage], pCell);
-        } else {
         szLCell = tdbBtreeCellSize(pOlds[infoNews[iNew - 1].iPage], pCell);
-
+        if (!childNotLeaf) {
+          szRCell = szLCell;
+        } else {
           int    iPage = infoNews[iNew - 1].iPage;
           int    oIdx = infoNews[iNew - 1].oIdx + 1;
           SPage *pPage;

source/libs/tdb/test/tdbTest.cpp

@@ -202,6 +202,8 @@ TEST(tdb_test, simple_test) {
       ret = tdbDbcOpen(pDb, &pDBC, NULL);
       GTEST_ASSERT_EQ(ret, 0);
 
+      tdbDbcMoveToFirst(pDBC);
+
       for (;;) {
         ret = tdbDbcNext(pDBC, &pKey, &kLen, &pVal, &vLen);
         if (ret < 0) break;
@@ -283,6 +285,8 @@ TEST(tdb_test, simple_test2) {
       ret = tdbDbcOpen(pDb, &pDBC, NULL);
       GTEST_ASSERT_EQ(ret, 0);
 
+      tdbDbcMoveToFirst(pDBC);
+
       for (;;) {
         ret = tdbDbcNext(pDBC, &pKey, &kLen, &pVal, &vLen);
         if (ret < 0) break;
@@ -341,7 +345,7 @@ TEST(tdb_test, simple_delete1) {
   GTEST_ASSERT_EQ(ret, 0);
 
   // open database
-  ret = tdbDbOpen("db.db", -1, -1, NULL, pEnv, &pDb);
+  ret = tdbDbOpen("db.db", -1, -1, tKeyCmpr, pEnv, &pDb);
   GTEST_ASSERT_EQ(ret, 0);
 
   tdbTxnOpen(&txn, 0, poolMalloc, poolFree, pPool, TDB_TXN_WRITE | TDB_TXN_READ_UNCOMMITTED);