From d5b2c9b17d4446f2108c41663f91ff8a5d8d0767 Mon Sep 17 00:00:00 2001
From: Chengpeng Yan <41809508+Reminiscent@users.noreply.github.com>
Date: Thu, 22 Sep 2022 18:11:03 +0800
Subject: [PATCH] planner: fix panic when prepare and execute the insert on
 duplicate (#37924)

close pingcap/tidb#37187
---
 executor/insert_test.go     | 13 +++++++++++++
 planner/core/planbuilder.go |  5 +++++
 2 files changed, 18 insertions(+)

diff --git a/executor/insert_test.go b/executor/insert_test.go
index d0d17199c13f7..06c9927bba008 100644
--- a/executor/insert_test.go
+++ b/executor/insert_test.go
@@ -352,6 +352,19 @@ func TestUpdateDuplicateKey(t *testing.T) {
 		"[kv:1062]Duplicate entry '1-2-4' for key 'PRIMARY'")
 }
 
+func TestIssue37187(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+
+	tk.MustExec("drop table if exists a, b")
+	tk.MustExec("create table t1 (a int(11) ,b varchar(100) ,primary key (a));")
+	tk.MustExec("create table t2 (c int(11) ,d varchar(100) ,primary key (c));")
+	tk.MustExec("prepare in1 from 'insert into t1 (a,b) select c,null from t2 t on duplicate key update b=t.d';")
+	err := tk.ExecToErr("execute in1;")
+	require.NoError(t, err)
+}
+
 func TestInsertWrongValueForField(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)
diff --git a/planner/core/planbuilder.go b/planner/core/planbuilder.go
index f00d0625c9cf0..14a9b169e5536 100644
--- a/planner/core/planbuilder.go
+++ b/planner/core/planbuilder.go
@@ -3895,6 +3895,11 @@ func (b *PlanBuilder) buildSelectPlanOfInsert(ctx context.Context, insert *ast.I
 					}
 					sel.Fields.Fields = append(sel.Fields.Fields, &ast.SelectField{Expr: colName, Offset: len(sel.Fields.Fields)})
 				}
+				defer func(originSelFieldLen int) {
+					// Revert the change for ast. Because when we use the 'prepare' and 'execute' statement it will both build plan which will cause problem.
+					// You can see the issue #37187 for more details.
+					sel.Fields.Fields = sel.Fields.Fields[:originSelFieldLen]
+				}(actualColLen)
 			}
 		}
 	}