From de0b4bc1c56ca3505736e629963e93970cbeed7d Mon Sep 17 00:00:00 2001
From: weiwentao <1375910710@qq.com>
Date: Tue, 19 Nov 2024 15:02:27 +0800
Subject: [PATCH] =?UTF-8?q?[mysql=E5=85=BC=E5=AE=B9=E6=80=A7]=20=E8=A7=A3?=
 =?UTF-8?q?=E5=86=B3group=5Fconcat=E9=95=BF=E5=BA=A6=E8=AE=A1=E7=AE=97?=
 =?UTF-8?q?=E4=B8=BA=E5=A4=8D=E6=95=B0=E7=9A=84=E9=97=AE=E9=A2=98?=
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---
 src/common/backend/utils/adt/varlena.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/backend/utils/adt/varlena.cpp b/src/common/backend/utils/adt/varlena.cpp
index 3d9bbf33c..72035429e 100644
--- a/src/common/backend/utils/adt/varlena.cpp
+++ b/src/common/backend/utils/adt/varlena.cpp
@@ -6434,7 +6434,7 @@ Datum group_concat_finalfn(PG_FUNCTION_ARGS)
         StringInfo state = (StringInfo)PG_GETARG_POINTER(0);
         int cur_charset = get_valid_charset_by_collation(PG_GET_COLLATION());
         int encoding_max_length = pg_wchar_table[cur_charset].maxmblen;
-        int real_len = state->len - encoding_max_length;
+        int real_len = state->len - encoding_max_length > 0 ? state->len - encoding_max_length : 0;
         char* real_data = state->data + real_len;
         while (real_data != NULL) {
             int cur_len = pg_wchar_table[cur_charset].mblen((const unsigned char*)real_data);