diff --git a/source/client/src/clientImpl.c b/source/client/src/clientImpl.c
index 71c5df6a09..63bb3637cf 100644
--- a/source/client/src/clientImpl.c
+++ b/source/client/src/clientImpl.c
@@ -737,7 +737,7 @@ static int32_t doConvertUCS4(SReqResultInfo* pResultInfo, int32_t numOfRows, int
     int32_t type = pResultInfo->fields[i].type;
     int32_t bytes = pResultInfo->fields[i].bytes;
 
-    if (type == TSDB_DATA_TYPE_NCHAR) {
+    if (type == TSDB_DATA_TYPE_NCHAR && colLength[i] > 0) {
       char* p = taosMemoryRealloc(pResultInfo->convertBuf[i], colLength[i]);
       if (p == NULL) {
         return TSDB_CODE_OUT_OF_MEMORY;
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index e308c9c2b9..b81872f20c 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -1414,7 +1414,7 @@ static int32_t doCopyRowsFromFileBlock(STsdbReadHandle* pTsdbReadHandle, int32_t
           }
 
           if (sVal.valType == TD_VTYPE_NULL) {
-            colDataAppend(pColInfo, k, NULL, true);
+            colDataAppendNULL(pColInfo, k);
           } else {
             colDataAppend(pColInfo, k, sVal.val, false);
           }
@@ -1427,7 +1427,11 @@ static int32_t doCopyRowsFromFileBlock(STsdbReadHandle* pTsdbReadHandle, int32_t
             TASSERT(0);
           }
 
-          colDataAppend(pColInfo, k, sVal.val, false);
+          if (sVal.valType == TD_VTYPE_NULL) {
+            colDataAppendNULL(pColInfo, k);
+          } else {
+            colDataAppend(pColInfo, k, sVal.val, false);
+          }
         }
       }
 
diff --git a/source/libs/executor/src/executorimpl.c b/source/libs/executor/src/executorimpl.c
index b86d75cc7b..b7bbb605c5 100644
--- a/source/libs/executor/src/executorimpl.c
+++ b/source/libs/executor/src/executorimpl.c
@@ -6682,38 +6682,6 @@ bool validateExprColumnInfo(SQueriedTableInfo* pTableInfo, SExprBasicInfo* pExpr
   return j != INT32_MIN;
 }
 
-static int32_t deserializeColFilterInfo(SColumnFilterInfo* pColFilters, int16_t numOfFilters, char** pMsg) {
-  for (int32_t f = 0; f < numOfFilters; ++f) {
-    SColumnFilterInfo* pFilterMsg = (SColumnFilterInfo*)(*pMsg);
-
-    SColumnFilterInfo* pColFilter = &pColFilters[f];
-    pColFilter->filterstr = htons(pFilterMsg->filterstr);
-
-    (*pMsg) += sizeof(SColumnFilterInfo);
-
-    if (pColFilter->filterstr) {
-      pColFilter->len = htobe64(pFilterMsg->len);
-
-      pColFilter->pz =
-          (int64_t)taosMemoryCalloc(1, (size_t)(pColFilter->len + 1 * TSDB_NCHAR_SIZE));  // note: null-terminator
-      if (pColFilter->pz == 0) {
-        return TSDB_CODE_QRY_OUT_OF_MEMORY;
-      }
-
-      memcpy((void*)pColFilter->pz, (*pMsg), (size_t)pColFilter->len);
-      (*pMsg) += (pColFilter->len + 1);
-    } else {
-      pColFilter->lowerBndi = htobe64(pFilterMsg->lowerBndi);
-      pColFilter->upperBndi = htobe64(pFilterMsg->upperBndi);
-    }
-
-    pColFilter->lowerRelOptr = htons(pFilterMsg->lowerRelOptr);
-    pColFilter->upperRelOptr = htons(pFilterMsg->upperRelOptr);
-  }
-
-  return TSDB_CODE_SUCCESS;
-}
-
 static SResSchema createResSchema(int32_t type, int32_t bytes, int32_t slotId, int32_t scale, int32_t precision,
                                   const char* name) {
   SResSchema s = {0};
diff --git a/tests/script/tsim/query/diff.sim b/tests/script/tsim/query/diff.sim
index ebbd470944..c55b080e44 100644
--- a/tests/script/tsim/query/diff.sim
+++ b/tests/script/tsim/query/diff.sim
@@ -63,20 +63,21 @@ print =============== step2
 $i = 1
 $tb = $tbPrefix . $i
 
-print ===> select diff(tbcol) from $tb
-sql select diff(tbcol) from $tb
+print ===> select _rowts, diff(tbcol) from $tb
+sql select _rowts, diff(tbcol) from $tb
 print ===> rows: $rows
 print ===> $data00 $data01 $data02 $data03 $data04 $data05
 print ===> $data10 $data11 $data12 $data13 $data14 $data15
-if $data11 != 1 then 
+if $data11 != 1 then
+  print expect 1, actual: $data11
   return -1
 endi
 
 print =============== step3
 $cc = 4 * 60000
 $ms = 1601481600000 + $cc
-print ===> select diff(tbcol) from $tb where ts > $ms
-sql select diff(tbcol) from $tb where ts > $ms
+print ===> select _rowts, diff(tbcol) from $tb where ts > $ms
+sql select _rowts, diff(tbcol) from $tb where ts > $ms
 print ===> rows: $rows
 print ===> $data00 $data01 $data02 $data03 $data04 $data05
 print ===> $data10 $data11 $data12 $data13 $data14 $data15
@@ -86,8 +87,8 @@ endi
 
 $cc = 4 * 60000
 $ms = 1601481600000 + $cc
-print ===> select diff(tbcol) from $tb where ts <= $ms
-sql select diff(tbcol) from $tb where ts <= $ms
+print ===> select _rowts, diff(tbcol) from $tb where ts <= $ms
+sql select _rowts, diff(tbcol) from $tb where ts <= $ms
 print ===> rows: $rows
 print ===> $data00 $data01 $data02 $data03 $data04 $data05
 print ===> $data10 $data11 $data12 $data13 $data14 $data15
@@ -96,8 +97,8 @@ if $data11 != 1 then
 endi
 
 print =============== step4
-print ===> select diff(tbcol) as b from $tb
-sql select diff(tbcol) as b from $tb
+print ===> select _rowts, diff(tbcol) as b from $tb
+sql select _rowts, diff(tbcol) as b from $tb
 print ===> rows: $rows
 print ===> $data00 $data01 $data02 $data03 $data04 $data05
 print ===> $data10 $data11 $data12 $data13 $data14 $data15
@@ -105,24 +106,24 @@ if $data11 != 1 then
   return -1
 endi
 
-print =============== step5
-print ===> select diff(tbcol) as b from $tb interval(1m)
-sql select diff(tbcol) as b from $tb interval(1m) -x step5
-  return -1
-step5:
-
-print =============== step6
-$cc = 4 * 60000
-$ms = 1601481600000 + $cc
-print ===> select diff(tbcol) as b from $tb where ts <= $ms interval(1m)
-sql select diff(tbcol) as b from $tb where ts <= $ms interval(1m) -x step6
-  return -1
+#print =============== step5
+#print ===> select diff(tbcol) as b from $tb interval(1m)
+#sql select diff(tbcol) as b from $tb interval(1m) -x step5
+#  return -1
+#step5:
+#
+#print =============== step6
+#$cc = 4 * 60000
+#$ms = 1601481600000 + $cc
+#print ===> select diff(tbcol) as b from $tb where ts <= $ms interval(1m)
+#sql select diff(tbcol) as b from $tb where ts <= $ms interval(1m) -x step6
+#  return -1
 step6:
 
 print =============== clear
 sql drop database $db
 sql show databases
-if $rows != 0 then 
+if $rows != 1 then
   return -1
 endi