diff --git a/src/query/src/qAggMain.c b/src/query/src/qAggMain.c
index 85b4cb5e8f2a36fcf14460ea45c34f2a65b9e194..8efc4aad4c82ce34047fb87e10db169a1d8e5e3f 100644
--- a/src/query/src/qAggMain.c
+++ b/src/query/src/qAggMain.c
@@ -2675,6 +2675,8 @@ static void col_project_function(SQLFunctionCtx *pCtx) {
   if (pCtx->numOfParams == 2) {
     return;
   }
+
+  // only one row is required.
   if (pCtx->param[0].i64 == 1) {
     SET_VAL(pCtx, pCtx->size, 1);
   } else {
@@ -2683,7 +2685,8 @@ static void col_project_function(SQLFunctionCtx *pCtx) {
 
   char *pData = GET_INPUT_DATA_LIST(pCtx);
   if (pCtx->order == TSDB_ORDER_ASC) {
-    memcpy(pCtx->pOutput, pData, (size_t) pCtx->size * pCtx->inputBytes);
+    int32_t numOfRows = (pCtx->param[0].i64 == 1)? 1:pCtx->size;
+    memcpy(pCtx->pOutput, pData, (size_t) numOfRows * pCtx->inputBytes);
   } else {
     for(int32_t i = 0; i < pCtx->size; ++i) {
       memcpy(pCtx->pOutput + (pCtx->size - 1 - i) * pCtx->inputBytes, pData + i * pCtx->inputBytes,