execution: fix the incorrect use of cached plan for point get (#24749) (

#24764)

session/session.go

@@ -1500,7 +1500,7 @@ func (s *session) IsCachedExecOk(ctx context.Context, preparedStmt *plannercore.
 		return false, nil
 	}
 	// check auto commit
-	if !s.GetSessionVars().IsAutocommit() {
+	if !plannercore.IsAutoCommitTxn(s) {
 		return false, nil
 	}
 	// check schema version

session/session_test.go

@@ -3612,3 +3612,61 @@ func (s *testSessionSerialSuite) TestParseWithParams(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(sb.String(), Equals, "SELECT 3")
 }
+
+func (s *testSessionSuite) TestInTxnPSProtoPointGet(c *C) {
+	ctx := context.Background()
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t1(c1 int primary key, c2 int, c3 int)")
+	tk.MustExec("insert into t1 values(1, 10, 100)")
+
+	// Generate the ps statement and make the prepared plan cached for point get.
+	id, _, _, err := tk.Se.PrepareStmt("select c1, c2 from t1 where c1 = ?")
+	c.Assert(err, IsNil)
+	idForUpdate, _, _, err := tk.Se.PrepareStmt("select c1, c2 from t1 where c1 = ? for update")
+	c.Assert(err, IsNil)
+	params := []types.Datum{types.NewDatum(1)}
+	rs, err := tk.Se.ExecutePreparedStmt(ctx, id, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 10"))
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, idForUpdate, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 10"))
+
+	// Query again the cached plan will be used.
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, id, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 10"))
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, idForUpdate, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 10"))
+
+	// Start a transaction, now the in txn flag will be added to the session vars.
+	_, err = tk.Se.Execute(ctx, "start transaction")
+	c.Assert(err, IsNil)
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, id, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 10"))
+	txn, err := tk.Se.Txn(false)
+	c.Assert(err, IsNil)
+	c.Assert(txn.Valid(), IsTrue)
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, idForUpdate, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 10"))
+	txn, err = tk.Se.Txn(false)
+	c.Assert(err, IsNil)
+	c.Assert(txn.Valid(), IsTrue)
+	_, err = tk.Se.Execute(ctx, "update t1 set c2 = c2 + 1")
+	c.Assert(err, IsNil)
+	// Check the read result after in-transaction update.
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, id, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 11"))
+	rs, err = tk.Se.ExecutePreparedStmt(ctx, idForUpdate, params)
+	c.Assert(err, IsNil)
+	tk.ResultSetToResult(rs, Commentf("%v", rs)).Check(testkit.Rows("1 11"))
+	txn, err = tk.Se.Txn(false)
+	c.Assert(err, IsNil)
+	c.Assert(txn.Valid(), IsTrue)
+	tk.MustExec("commit")
+}