wrong result for query containing subquery when plan cache is enabled

[eurekaka]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

• start tidb-server with plan cache enabled;
• create session 1, and execute:

mysql> create table t(a int, b int);
Query OK, 0 rows affected (0.05 sec)

mysql> prepare stmt from 'select * from t where a = (select a from t where a = ?)';
Query OK, 0 rows affected (0.01 sec)

mysql> set @param = 1;
Query OK, 0 rows affected (0.00 sec)

mysql> execute stmt using @param;
Empty set (0.00 sec)

• keep session 1 connected, create session 2, and execute:

mysql> insert into t values(1,1);
Query OK, 1 row affected (0.00 sec)

• back to session 1:

mysql> select * from t;
+------+------+
| a    | b    |
+------+------+
|    1 |    1 |
+------+------+
1 row in set (0.00 sec)

mysql> execute stmt using @param;
Empty set (0.00 sec)

mysql> select * from t where a = (select a from t where a = 1);
+------+------+
| a    | b    |
+------+------+
|    1 |    1 |
+------+------+
1 row in set (0.00 sec)

2. What did you expect to see?

second execute stmt using @param; in session 1 should return one row.

3. What did you see instead?

second execute stmt using @param; in session 1 returns empty result.

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

mysql> select tidb_version();
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version()                                                                                                                                                                                                                                                                                                 |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: None
Git Commit Hash: a4cff40a18da37b146ad763a8f7cd6756fdf569d
Git Branch: master
UTC Build Time: 2018-10-24 06:46:18
GoVersion: go version go1.11rc1 linux/amd64
Race Enabled: false
TiKV Min Version: 2.1.0-alpha.1-ff3dd160846b7d1aed9079c389fc188f7f5ea13e
Check Table Before Drop: false |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)