diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index d2c52e972af5aa65bc97497f93936187fc97164f..d0141835a38df44515e4a36627e42fa11718d97b 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -229,8 +229,9 @@ typedef struct STableDataBlocks {
 
 typedef struct SQueryInfo {
   int16_t          command;       // the command may be different for each subclause, so keep it seperately.
-  uint32_t         type;          // query/insert type
+  char             intervalTimeUnit;
   char             slidingTimeUnit;
+  uint32_t         type;          // query/insert type
   STimeWindow      window;        // query time window
   int64_t          intervalTime;  // aggregation time interval
   int64_t          slidingTime;   // sliding window in mseconds
diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 5ce4c7125f3111cead393057e55e977e5cb6ede1..1fb8594588e05f533a3fb8b5458e3d5179e18560 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -586,22 +586,21 @@ int32_t parseIntervalClause(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, SQuerySQL* pQ
   }
 
   // interval is not null
-  SStrToken* t = &pQuerySql->interval;
-  if (getTimestampInUsFromStr(t->z, t->n, &pQueryInfo->intervalTime) != TSDB_CODE_SUCCESS) {
+  SSQLToken* t = &pQuerySql->interval;
+  if (parseDuration(t->z, t->n, &pQueryInfo->intervalTime, &pQueryInfo->intervalTimeUnit) != TSDB_CODE_SUCCESS) {
     return TSDB_CODE_TSC_INVALID_SQL;
   }
 
-  // if the unit of time window value is millisecond, change the value from microsecond
-  if (tinfo.precision == TSDB_TIME_PRECISION_MILLI) {
-    pQueryInfo->intervalTime = pQueryInfo->intervalTime / 1000;
-  }
-
-  /* parser has filter the illegal type, no need to check here */
-  pQueryInfo->slidingTimeUnit = pQuerySql->interval.z[pQuerySql->interval.n - 1];
+  if (pQueryInfo->intervalTimeUnit != 'n' && pQueryInfo->intervalTimeUnit != 'y') {
+    // if the unit of time window value is millisecond, change the value from microsecond
+    if (tinfo.precision == TSDB_TIME_PRECISION_MILLI) {
+      pQueryInfo->intervalTime = pQueryInfo->intervalTime / 1000;
+    }
 
-  // interval cannot be less than 10 milliseconds
-  if (pQueryInfo->intervalTime < tsMinIntervalTime) {
-    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
+    // interval cannot be less than 10 milliseconds
+    if (pQueryInfo->intervalTime < tsMinIntervalTime) {
+      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
+    }
   }
 
   // for top/bottom + interval query, we do not add additional timestamp column in the front
@@ -666,28 +665,35 @@ int32_t parseSlidingClause(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, SQuerySQL* pQu
   const char* msg0 = "sliding value too small";
   const char* msg1 = "sliding value no larger than the interval value";
   const char* msg2 = "sliding value can not less than 1% of interval value";
+  const char* msg3 = "does not support sliding when interval is natual month/year";
 
   const static int32_t INTERVAL_SLIDING_FACTOR = 100;
 
   STableMetaInfo* pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
   STableComInfo tinfo = tscGetTableInfo(pTableMetaInfo->pTableMeta);
 
-  SStrToken* pSliding = &pQuerySql->sliding;
-  if (pSliding->n != 0) {
-    getTimestampInUsFromStr(pSliding->z, pSliding->n, &pQueryInfo->slidingTime);
-    if (tinfo.precision == TSDB_TIME_PRECISION_MILLI) {
-      pQueryInfo->slidingTime /= 1000;
-    }
+  SSQLToken* pSliding = &pQuerySql->sliding;
+  if (pSliding->n == 0) {
+    pQueryInfo->slidingTimeUnit = pQueryInfo->intervalTimeUnit;
+    pQueryInfo->slidingTime = pQueryInfo->intervalTime;
+    return TSDB_CODE_SUCCESS;
+  }
 
-    if (pQueryInfo->slidingTime < tsMinSlidingTime) {
-      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg0);
-    }
+  if (pQueryInfo->intervalTimeUnit == 'n' || pQueryInfo->intervalTimeUnit == 'y') {
+    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg3);
+  }
 
-    if (pQueryInfo->slidingTime > pQueryInfo->intervalTime) {
-      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
-    }
-  } else {
-    pQueryInfo->slidingTime = pQueryInfo->intervalTime;
+  getTimestampInUsFromStr(pSliding->z, pSliding->n, &pQueryInfo->slidingTime);
+  if (tinfo.precision == TSDB_TIME_PRECISION_MILLI) {
+    pQueryInfo->slidingTime /= 1000;
+  }
+
+  if (pQueryInfo->slidingTime < tsMinSlidingTime) {
+    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg0);
+  }
+
+  if (pQueryInfo->slidingTime > pQueryInfo->intervalTime) {
+    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
   }
 
   if ((pQueryInfo->intervalTime != 0) && (pQueryInfo->intervalTime/pQueryInfo->slidingTime > INTERVAL_SLIDING_FACTOR)) {
diff --git a/src/os/inc/osTime.h b/src/os/inc/osTime.h
index cd2553f75336bc00225b4292638b3eb96f082ae9..97432ca24112805b1352b47e1ba2e34503477fb3 100644
--- a/src/os/inc/osTime.h
+++ b/src/os/inc/osTime.h
@@ -64,6 +64,7 @@ static FORCE_INLINE int64_t taosGetTimestamp(int32_t precision) {
 }
 
 int32_t getTimestampInUsFromStr(char* token, int32_t tokenlen, int64_t* ts);
+int32_t parseDuration(const char* token, int32_t tokenLen, int64_t* duration, char* unit);
 
 int32_t taosParseTime(char* timestr, int64_t* time, int32_t len, int32_t timePrec, int8_t dayligth);
 void deltaToUtcInitOnce();
diff --git a/src/os/src/detail/osTime.c b/src/os/src/detail/osTime.c
index 57634e468a87c9e482794fe1937a108d646cfaa1..9d8328a71b19c5a37eaa29fba8f2844c95dd77ca 100644
--- a/src/os/src/detail/osTime.c
+++ b/src/os/src/detail/osTime.c
@@ -319,6 +319,8 @@ int32_t parseLocaltimeWithDst(char* timestr, int64_t* time, int32_t timePrec) {
   *time = factor * seconds + fraction;
   return 0;
 }
+
+
 static int32_t getTimestampInUsFromStrImpl(int64_t val, char unit, int64_t* result) {
   *result = val;
 
@@ -384,6 +386,23 @@ int32_t getTimestampInUsFromStr(char* token, int32_t tokenlen, int64_t* ts) {
   return getTimestampInUsFromStrImpl(timestamp, token[tokenlen - 1], ts);
 }
 
+int32_t parseDuration(const char* token, int32_t tokenLen, int64_t* duration, char* unit) {
+  errno = 0;
+
+  /* get the basic numeric value */
+  *duration = strtoll(token, NULL, 10);
+  if (errno != 0) {
+    return -1;
+  }
+
+  *unit = token[tokenLen - 1];
+  if (*unit == 'n' || *unit == 'y') {
+    return 0;
+  }
+
+  return getTimestampInUsFromStrImpl(*duration, *unit, duration);
+}
+
 // internal function, when program is paused in debugger,
 // one can call this function from debugger to print a
 // timestamp as human readable string, for example (gdb):