Wrong result when update ... set ... on same table

[Deardrops]

Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

create table t(x int, y int);
insert into t values();
update t t1, t t2 set t2.y=1, t1.x=2;
select * from t;

2. What did you expect to see?

3. What did you see instead?

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

SIG slack channel

#sig-exec

Score

• 300

Mentor

• @qw4990

[ghost]

Confirming this issue still exists in master:

DROP TABLE IF EXISTS t;
create table t(x int, y int);
insert into t values();
update t t1, t t2 set t2.y=1, t1.x=2;
select * from t;

..

mysql> select * from t;
+------+------+
| x    | y    |
+------+------+
|    2 | NULL |
+------+------+
1 row in set (0.00 sec)

mysql> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v4.0.0-beta.2-771-gca41972fb
Edition: Community
Git Commit Hash: ca41972fbac068c8a5de107d9075f09ac68842ac
Git Branch: master
UTC Build Time: 2020-07-14 02:41:21
GoVersion: go1.13
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false
1 row in set (0.00 sec)

[time-and-fate]

/assign time-and-fate

[SunRunAway]

cc @dyzsr

[jebter]

/assign dyzsr

[dyzsr]

/assign

[ti-srebot]

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