From a16a6b73c8ff73976daa63a667a339184113e4d1 Mon Sep 17 00:00:00 2001
From: shenglian zhou <slzhou@taosdata.com>
Date: Sat, 6 Aug 2022 20:11:12 +0800
Subject: [PATCH] fix: force at least one row for agg/window group

---
 source/libs/executor/src/executorimpl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/source/libs/executor/src/executorimpl.c b/source/libs/executor/src/executorimpl.c
index 7c19ad024e..b99efce106 100644
--- a/source/libs/executor/src/executorimpl.c
+++ b/source/libs/executor/src/executorimpl.c
@@ -1448,6 +1448,10 @@ static void doUpdateNumOfRows(SResultRow* pRow, int32_t numOfExprs, const int32_
       pRow->numOfRows = pResInfo->numOfRes;
     }
   }
+  // TODO: if all expr skips all blocks, e.g. all null inputs for max function, output one row in final result.
+  if (pRow->numOfRows == 0) {
+    pRow->numOfRows = 1;
+  }
 }
 
 // todo extract method with copytoSSDataBlock