prepare statement can't receive schema update

[ichn-hu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

start a session, execute:

use test;
create table t (a int);
create table t_a (a int);
insert into t values (1), (2), (3);

then, using the following code to connect

package main

import (
        // "bufio"

        "fmt"
        "log"
        "os"

        // "strings"
        "time"

        _ "github.com/go-sql-driver/mysql"
        "github.com/jmoiron/sqlx"
)

const (
        DBIp      = "127.0.0.1"
        DBPort    = "4000"
        DBUser    = "root"
        DBPwd     = ""
        DBName    = "test"
        SelectSQL = "SELECT count(*) as cnt,CONNECTION_ID() as conntid FROM t where a = ?"
        a1        = "1"
)

var (
        dBDsnWithName = fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?charset=latin1&autocommit=1&parseTime=true&loc=Local&timeout=3000s&writeTimeout=1000s&readTimeout=1000s", DBUser, DBPwd, DBIp, DBPort, DBName)
)

// User for test
type User struct {
        Count  int `db:"cnt"`
        Connid int `db:"conntid"`
}

func main() {
        db, err := sqlx.Open("mysql", dBDsnWithName)
        // db, err := sql.Open("mysql", dBDsnWithName)
        if err != nil {
                log.Fatalf("error in opening database: %+v", err)
                os.Exit(1)
        }
        db.SetMaxOpenConns(8)
        db.SetMaxIdleConns(2)
        log.Println("finished database initialization...")
        var u User
        var i int
        for i < 20 {
                err = db.Get(&u, SelectSQL, a1)
                // err := db.QueryRow(SelectSQL, c1).Scan(&cnt, &cnntid)
                if err != nil {
                        log.Printf("db error: %v", err)
                }
                log.Printf("user: %v", u)
                // log.Printf("cnt: %v , connect_id: %v", cnt, cnntid)
                time.Sleep(5 * time.Second)
                i++
        }
        log.Println("finished testing...")
}

while the above code is executing, rename the 2 tables in another session

alter table rename t to t_b;
alter table rename t_a to t;

2. What did you expect to see? (Required)

No error.

3. What did you see instead (Required)

$ go run ./test_main.go
2021/06/16 16:32:48 finished database initialization...
2021/06/16 16:32:48 user: {1 13}
2021/06/16 16:32:53 user: {1 13}
2021/06/16 16:32:58 user: {1 13}
2021/06/16 16:33:03 user: {1 13}
2021/06/16 16:33:08 user: {1 13}
2021/06/16 16:33:13 db error: Error 1146: Table 'test.t' doesn't exist
2021/06/16 16:33:13 user: {1 13}
2021/06/16 16:33:18 db error: Error 1146: Table 'test.t' doesn't exist
2021/06/16 16:33:18 user: {1 13}
2021/06/16 16:33:23 db error: Error 1146: Table 'test.t' doesn't exist
2021/06/16 16:33:23 user: {1 13}
2021/06/16 16:33:28 db error: Error 1146: Table 'test.t' doesn't exist
2021/06/16 16:33:28 user: {1 13}

4. What is your TiDB version? (Required)

select tidb_version();
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    15
Current database: las_tc

+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version()                                                                                                                                                                                                                                                                                                             |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v5.1.0-alpha-6-gd5d433e49
Edition: Community
Git Commit Hash: d5d433e49dd20420f9165005c92b3e1592ab8c6b
Git Branch: fix-prepare
UTC Build Time: 2021-06-15 11:23:23
GoVersion: go1.16
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

[xhebox]

Can not reproduce. My output:

2021/06/16 20:12:37 finished database initialization...
2021/06/16 20:12:37 user: {1 7}
2021/06/16 20:12:42 user: {1 7}
alter table t rename to t_b; alter table t_a rename to t;
2021/06/16 20:12:47 user: {0 7}
2021/06/16 20:12:52 user: {0 7}
2021/06/16 20:12:57 user: {0 7}
2021/06/16 20:13:02 user: {0 7}
2021/06/16 20:13:07 user: {0 7}
2021/06/16 20:13:12 user: {0 7}
2021/06/16 20:13:17 user: {0 7}
2021/06/16 20:13:22 user: {0 7}
2021/06/16 20:13:27 user: {0 7}
2021/06/16 20:13:32 user: {0 7}

Don't know why though, the problem of prepare does exist.

[ichn-hu]

@xhebox to reproduce, you show run the two rename ddl separately, run the first rename, wait until the error occurred, and then run the second. it is expected that the error will disappear after the second ddl, but it doesn't.

[ichn-hu]

@xhebox and I found it can be reproduced on v4.0.11, but not master.

[ichn-hu]

and on d5d433e49dd20420f9165005c92b3e1592ab8c6b it can be reproduced.

[ichn-hu]

and on d5d433e49dd20420f9165005c92b3e1592ab8c6b it can be reproduced.

sorry, this is my local development commit, the merge-base between it and master is

$ git merge-base HEAD d5d433e49dd20420f9165005c92b3e1592ab8c6b                                                                                          1 ↵
19e100c27a37601d674df625034ebddb5196a299

and it can be reproduced on the merge-base.

[ichn-hu]

after bisect, I found it is fixed in bfdad7c, i.e. #24820

[xhebox]

Why it can be reproduced on v4.0.11? I thought the problem is introduced by me. But I never cherry-pick them back to 4.0.

[ichn-hu]

I think the problem exists already before your change

[ichn-hu]

and you happens to fixed it in bfdad7c#diff-10dab83c04a99358d431906d37f48b92be97d50a2719d4ddf81c62d3b03a0aebR2883-R2895

[ichn-hu]

do you have any suggestions for the fix on v4.0.11?

[xhebox]

OK, I remembered the case. Here is the issue, #24233. And it is not cherry-picked because they worry about the stability of these 3 PRs. These PRs are developed as some fixes for stale read feature.

By 3 PRs, I finally get most operations of getting infoschema consistent, and the problem may come from some inconsistent behaviors fixed by PRs. Maybe cherry-icking all 3 PRs will fix the problem...

[ichn-hu]

@xhebox would you like to take over this issue?

[xhebox]

Is it urgent? I don't think I have time today or tomorrow.

[ichn-hu]

nope, you can do it any time in the future (better before next 4.x release)

…

On Thu, Jun 17, 2021 at 5:18 PM xhe ***@***.***> wrote: Is it urgent? I don't think I have time today or tomorrow. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#25482 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AHC3V5N2EZEQCBIMXT65H6TTTG4XNANCNFSM46Y5T6AA> .

[ichn-hu]

/assign @xhebox

[xiongjiwei]

have been fixed in 5.1

[ti-srebot]

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