From 1d795f5c62e4102c45b6263a234b74c5a08f7283 Mon Sep 17 00:00:00 2001
From: Cary Xu <klxu@taosdata.com>
Date: Mon, 14 Nov 2022 16:27:02 +0800
Subject: [PATCH] fix: null pointer when merge col data of varchar

---
 source/common/src/tdatablock.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index e8d5989e4d..f7b1196248 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -277,7 +277,9 @@ int32_t colDataMergeCol(SColumnInfoData* pColumnInfoData, int32_t numOfRow1, int
       pColumnInfoData->varmeta.allocLen = len + oldLen;
     }
 
-    memcpy(pColumnInfoData->pData + oldLen, pSource->pData, len);
+    if (pColumnInfoData->pData && pSource->pData) { // TD-20382
+      memcpy(pColumnInfoData->pData + oldLen, pSource->pData, len);
+    }
     pColumnInfoData->varmeta.length = len + oldLen;
   } else {
     if (finalNumOfRows > (*capacity)) {
-- 
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