enh(query): avg function adoption for MIA operator

TD-17254

source/libs/function/src/builtinsimpl.c

@@ -908,10 +908,12 @@ int32_t avgFunctionMerge(SqlFunctionCtx* pCtx) {
   SAvgRes* pInfo = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));
 
   int32_t start = pInput->startRowIndex;
-  char*    data = colDataGetData(pCol, start);
-  SAvgRes* pInputInfo = (SAvgRes*)varDataVal(data);
 
+  for(int32_t i = start; i < start + pInput->numOfRows; ++i) {
+    char* data = colDataGetData(pCol, i);
+    SAvgRes* pInputInfo = (SAvgRes*)varDataVal(data);
     avgTransferInfo(pInputInfo, pInfo);
+  }
 
   SET_VAL(GET_RES_INFO(pCtx), 1, 1);