From 0debaf1e410554a1b3042c03d0a9aad9fd54d53f Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Tue, 26 Apr 2022 15:05:03 +0800
Subject: [PATCH] fix(query): recalculate the length of all null constant
 column.

---
 source/common/src/tdatablock.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index 09452b584d..5270bdeb46 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -79,7 +79,11 @@ int32_t colDataGetLength(const SColumnInfoData* pColumnInfoData, int32_t numOfRo
   if (IS_VAR_DATA_TYPE(pColumnInfoData->info.type)) {
     return pColumnInfoData->varmeta.length;
   } else {
-    return pColumnInfoData->info.bytes * numOfRows;
+    if (pColumnInfoData->info.type == TSDB_DATA_TYPE_NULL) {
+      return 0;
+    } else {
+      return pColumnInfoData->info.bytes * numOfRows;
+    }
   }
 }