Enlarge `state` field from `information_schema.processlist` · pingcap/tidb#28311

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compatibility-mysql8help wantedseverity/minorsig/sql-infratype/bug

Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

mysql> desc information_schema.processlist;
+----------+---------------------+------+------+---------+-------+
| Field    | Type                | Null | Key  | Default | Extra |
+----------+---------------------+------+------+---------+-------+
| ID       | bigint(21) unsigned | NO   |      | 0       |       |
| USER     | varchar(16)         | NO   |      |         |       |
| HOST     | varchar(64)         | NO   |      |         |       |
| DB       | varchar(64)         | YES  |      | NULL    |       |
| COMMAND  | varchar(16)         | NO   |      |         |       |
| TIME     | int(7)              | NO   |      | 0       |       |
| STATE    | varchar(7)          | YES  |      | NULL    |       |
| INFO     | longtext            | YES  |      | NULL    |       |
| DIGEST   | varchar(64)         | YES  |      |         |       |
| MEM      | bigint(21) unsigned | YES  |      | NULL    |       |
| DISK     | bigint(21) unsigned | YES  |      | NULL    |       |
| TxnStart | varchar(64)         | NO   |      |         |       |
+----------+---------------------+------+------+---------+-------+
12 rows in set (0.09 sec)

mysql> select state from information_schema.processlist;
+------------+
| state      |
+------------+
| autocommit |
+------------+

The column type of state is varchar(7) but the length of "autocommit" is 10.

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

The length should be at least 20(ref).

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

commit f830d012d29c6add78053da4c8432275067aaae0 (HEAD)
Author: wjhuang2016 <huangwenjun1997@gmail.com>
Date:   Fri Sep 24 16:58:11 2021 +0800

    refine comment
    
    Signed-off-by: wjhuang2016 <huangwenjun1997@gmail.com>

Contributor guide

Tech stack: gosql
Domain: database
Issue type: bug
Difficulty: 2
Estimated time: under 1 hour
Activity status: blocked
Clarity: clear
Prerequisites: Go programmingDatabase schema concepts
Newbie friendliness: 30
Research direction: The issue is to enlarge the `state` field in `information schema.processlist` from `varchar(7)` to `varchar(20)`. The current definition is in `util/processinfo.go` at line 141 (ref: https://github.com/pingcap/tidb/blob/7755d25aba5120dafde98fff11ab3b98ca4d192f/util/processinfo.go#L141). A contributor should locate this definition, update the size to 20, and verify if any other schema definitions or tests need corresponding changes. The change is localized and straightforward, but note that the issue has an assignee, so check if it's still available.