query information_schema.tables will report table not exists

[xiongjiwei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. create a table that contains an auto_increament column and then drop the table
2. run query SELECT 1 FROM information_schema.tables

parallel run these two steps several times, you may get an error Table xxx doesn't exist

this is because

tidb/executor/infoschema_reader.go

Lines 687 to 692 in 5ff5b34

	if hasAutoIncID {
	autoIncID, err = getAutoIncrementID(sctx, schema, table)
	if err != nil {
	return err
	}
	}

getAutoIncrementID will use the newest schema that the table has been dropped.
sleep seconds at L687 will easier to reproduce this bug

similar with #41622

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

[tiancaiamao]

A test script to reproduce, go run test.go and check whether the output is "Error 1146: Table 'test.xxx' doesn't exist"

package main

import (
        "database/sql"
        "flag"
        "fmt"
        _ "github.com/go-sql-driver/mysql"
)

func main() {
        var (
                host                        string
                port                        int
                user                        string
                passwd                      string
                dbname                      string
        )
        flag.StringVar(&host, "host", "127.0.0.1", "")
        flag.IntVar(&port, "port", 4000, "")
        flag.StringVar(&user, "user", "root", "")
        flag.StringVar(&passwd, "password", "", "")
        flag.StringVar(&dbname, "dbname", "test", "")
        flag.Parse()

        db, err := sql.Open("mysql", fmt.Sprintf("%s:%s@tcp(%s:%d)/%s", user, passwd, host, port, dbname))
        if err != nil {
                panic(err)
        }
        if err := db.Ping(); err != nil {
                panic(err)
        }
        defer db.Close()


        go func() {
                for {
                        res, err := db.Query("SELECT 1 FROM information_schema.tables")
                        if err != nil {
                                fmt.Println(err)
                        }
                        if res != nil {
                                res.Close()
                        }
                }
        }()

        for {
                _, err := db.Exec("create table xxx (id int key auto_increment)")
                if err != nil {
                        panic("create table failed")
                }

                _, err = db.Exec("drop table xxx")
                if err != nil {
                        panic("drop table failed")
                }
        }
}

[tiancaiamao]

Introduced by http://github.com/pingcap/tidb/pull/24820

[xiongjiwei]

maybe also the same root cause of #42007