diff --git a/src/client/CMakeLists.txt b/src/client/CMakeLists.txt
index ac1894369d..00fa1a1479 100644
--- a/src/client/CMakeLists.txt
+++ b/src/client/CMakeLists.txt
@@ -34,7 +34,9 @@ IF ((TD_LINUX_64) OR (TD_LINUX_32 AND TD_ARM))
         VERSION_INFO)
   MESSAGE(STATUS "build version ${VERSION_INFO}")
   SET_TARGET_PROPERTIES(taos PROPERTIES VERSION ${VERSION_INFO} SOVERSION 1)
-  
+
+  ADD_SUBDIRECTORY(tests)
+
 ELSEIF (TD_WINDOWS_64)
   INCLUDE_DIRECTORIES(${TD_COMMUNITY_DIR}/deps/jni/windows)
   INCLUDE_DIRECTORIES(${TD_COMMUNITY_DIR}/deps/jni/windows/win32)
diff --git a/src/client/tests/CMakeLists.txt b/src/client/tests/CMakeLists.txt
new file mode 100644
index 0000000000..f07af85e25
--- /dev/null
+++ b/src/client/tests/CMakeLists.txt
@@ -0,0 +1,15 @@
+CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
+PROJECT(TDengine)
+
+FIND_PATH(HEADER_GTEST_INCLUDE_DIR gtest.h /usr/include/gtest /usr/local/include/gtest)
+FIND_LIBRARY(LIB_GTEST_STATIC_DIR libgtest.a /usr/lib/ /usr/local/lib)
+
+IF (HEADER_GTEST_INCLUDE_DIR AND LIB_GTEST_STATIC_DIR)
+    MESSAGE(STATUS "gTest library found, build unit test")
+
+    INCLUDE_DIRECTORIES(${HEADER_GTEST_INCLUDE_DIR})
+    AUX_SOURCE_DIRECTORY(${CMAKE_CURRENT_SOURCE_DIR} SOURCE_LIST)
+
+    ADD_EXECUTABLE(cliTest ${SOURCE_LIST})
+    TARGET_LINK_LIBRARIES(cliTest taos tutil common gtest pthread)
+ENDIF()
\ No newline at end of file
diff --git a/src/common/src/ttimezone.c b/src/common/src/ttimezone.c
index ae6ffea59a..ed62357c4d 100644
--- a/src/common/src/ttimezone.c
+++ b/src/common/src/ttimezone.c
@@ -20,6 +20,7 @@
 #include "tconfig.h"
 #include "tutil.h"
 
+// TODO refactor to set the tz value through parameter
 void tsSetTimeZone() {
   SGlobalCfg *cfg_timezone = taosGetConfigOption("timezone");
   uPrint("timezone is set to %s by %s", tsTimezone, tsCfgStatusStr[cfg_timezone->cfgStatus]);
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index ed529db92e..cdb56e1469 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -822,7 +822,7 @@ static char *getDataBlock(SQueryRuntimeEnv *pRuntimeEnv, SArithmeticSupport *sas
 }
 
 /**
- *
+ * todo set the last value for pQueryTableInfo as in rowwiseapplyfunctions
  * @param pRuntimeEnv
  * @param forwardStep
  * @param tsCols
@@ -1064,16 +1064,18 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
 
   SQuery *pQuery = pRuntimeEnv->pQuery;
   STableQueryInfo* item = pQuery->current;
-  
-  TSKEY  *tsCols = (TSKEY*) ((SColumnInfoData *)taosArrayGet(pDataBlock, 0))->pData;
-  bool    groupbyStateValue = isGroupbyNormalCol(pQuery->pGroupbyExpr);
+
+  SColumnInfoData* pColumnInfoData = (SColumnInfoData *)taosArrayGet(pDataBlock, 0);
+
+  TSKEY  *tsCols = (pColumnInfoData->info.type == TSDB_DATA_TYPE_TIMESTAMP)? (TSKEY*) pColumnInfoData->pData:NULL;
+  bool    groupbyColumnValue = isGroupbyNormalCol(pQuery->pGroupbyExpr);
   SArithmeticSupport *sasArray = calloc((size_t)pQuery->numOfOutput, sizeof(SArithmeticSupport));
 
   int16_t type = 0;
   int16_t bytes = 0;
 
   char *groupbyColumnData = NULL;
-  if (groupbyStateValue) {
+  if (groupbyColumnValue) {
     groupbyColumnData = getGroupbyColumnData(pQuery, &type, &bytes, pDataBlock);
   }
 
@@ -1161,7 +1163,7 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
       pWindowResInfo->curIndex = index;
     } else {  // other queries
       // decide which group this rows belongs to according to current state value
-      if (groupbyStateValue) {
+      if (groupbyColumnValue) {
         char *val = groupbyColumnData + bytes * offset;
 
         int32_t ret = setGroupResultOutputBuf(pRuntimeEnv, val, type, bytes);
@@ -1186,9 +1188,14 @@ static void rowwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, SDataStatis *pS
       }
     }
   }
-  
-  item->lastKey = tsCols[offset] + step;
-  
+
+  assert(offset >= 0);
+  if (tsCols != NULL) {
+    item->lastKey = tsCols[offset] + step;
+  } else {
+    item->lastKey = (QUERY_IS_ASC_QUERY(pQuery)? pDataBlockInfo->window.ekey:pDataBlockInfo->window.skey) + step;
+  }
+
   // todo refactor: extract method
   for(int32_t i = 0; i < pQuery->numOfOutput; ++i) {
     if (pQuery->pSelectExpr[i].base.functionId != TSDB_FUNC_ARITHM) {
diff --git a/src/tsdb/src/tsdbMeta.c b/src/tsdb/src/tsdbMeta.c
index 6b0224cad2..e8da25d585 100644
--- a/src/tsdb/src/tsdbMeta.c
+++ b/src/tsdb/src/tsdbMeta.c
@@ -553,10 +553,18 @@ int tsdbUnlockRepoMeta(STsdbRepo *pRepo) {
   return 0;
 }
 
-void tsdbRefTable(STable *pTable) { T_REF_INC(pTable); }
+void tsdbRefTable(STable *pTable) {
+  int16_t ref = T_REF_INC(pTable);
+  tsdbTrace("ref table:%s, uid:%"PRIu64", tid:%d, ref:%d", TABLE_CHAR_NAME(pTable), pTable->tableId.uid, pTable->tableId.tid, ref);
+}
 
 void tsdbUnRefTable(STable *pTable) {
-  if (T_REF_DEC(pTable) == 0) {
+  int16_t ref = T_REF_DEC(pTable);
+  tsdbTrace("unref table:%s, uid:%"PRIu64", tid:%d, ref:%d", TABLE_CHAR_NAME(pTable), pTable->tableId.uid, pTable->tableId.tid, ref);
+
+  if (ref == 0) {
+    tsdbTrace("destroy table:%s uid:%"PRIu64", tid:%d", TABLE_CHAR_NAME(pTable), pTable->tableId.uid, pTable->tableId.tid);
+
     if (TABLE_TYPE(pTable) == TSDB_CHILD_TABLE) {
       tsdbUnRefTable(pTable->pSuper);
     }
diff --git a/src/util/src/tskiplist.c b/src/util/src/tskiplist.c
index 2394adc6f3..f3c0babe6b 100644
--- a/src/util/src/tskiplist.c
+++ b/src/util/src/tskiplist.c
@@ -38,7 +38,7 @@ static FORCE_INLINE int32_t getSkipListNodeRandomHeight(SSkipList *pSkipList) {
   const uint32_t factor = 4;
 
   int32_t n = 1;
-  while ((taosRand() % factor) == 0 && n <= pSkipList->maxLevel) {
+  while ((rand() % factor) == 0 && n <= pSkipList->maxLevel) {
     n++;
   }
 
diff --git a/src/util/src/ttime.c b/src/util/src/ttime.c
index dfec632012..176f9be7fb 100644
--- a/src/util/src/ttime.c
+++ b/src/util/src/ttime.c
@@ -48,23 +48,21 @@ int64_t user_mktime64(const unsigned int year0, const unsigned int mon0,
 		const unsigned int day, const unsigned int hour,
 		const unsigned int min, const unsigned int sec)
 {
-	unsigned int mon = mon0, year = year0;
+  unsigned int mon = mon0, year = year0;
 
-	/* 1..12 -> 11,12,1..10 */
-	if (0 >= (int) (mon -= 2)) {
-		mon += 12;	/* Puts Feb last since it has leap day */
-		year -= 1;
-	}
+  /* 1..12 -> 11,12,1..10 */
+  if (0 >= (int) (mon -= 2)) {
+    mon += 12;	/* Puts Feb last since it has leap day */
+    year -= 1;
+  }
 
-  //int64_t res = (((((int64_t) (year/4 - year/100 + year/400 + 367*mon/12 + day) +
-	//	  year*365 - 719499)*24 + hour)*60 + min)*60 + sec);
-  int64_t res;
-  res  = 367*((int64_t)mon)/12;
-  res += year/4 - year/100 + year/400 + day + year*365 - 719499;
+  int64_t res = 367*((int64_t)mon)/12;
+
+  res += ((int64_t)(year/4 - year/100 + year/400 + day + year*365) - 719499);  // this value may be less than 0
   res  = res*24;
   res  = ((res + hour) * 60 + min) * 60 + sec;  
 
-	return (res + timezone);
+  return (res + timezone);
 }
 // ==== mktime() kernel code =================//
 static int64_t m_deltaUtc = 0;
diff --git a/tests/script/general/parser/projection_limit_offset.sim b/tests/script/general/parser/projection_limit_offset.sim
index 5f006d0eb7..2b89946ef8 100644
--- a/tests/script/general/parser/projection_limit_offset.sim
+++ b/tests/script/general/parser/projection_limit_offset.sim
@@ -80,6 +80,7 @@ print $rows
 
 sql select ts from group_mt0 where ts>='1970-1-1 8:1:43' and ts<='1970-1-1 8:1:43.500' limit 8000 offset 0;
 if $rows != 4008 then
+  print expect 4008, actual:$rows
   return -1
 endi