Slow Field Addition, Unable to Add, System Hangs

Note:
This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: 添加字段慢,添加不上卡死

| username: Hacker_0LElpqkb

【TiDB Usage Environment】Production Environment / Testing / PoC
【TiDB Version】
【Reproduction Path】What operations were performed when the issue occurred
【Encountered Issue: Issue Phenomenon and Impact】
【Resource Configuration】Go to TiDB Dashboard - Cluster Info - Hosts and take a screenshot of this page
【Attachments: Screenshots / Logs / Monitoring】
Data volume around 300,000


Task status is always delete only
1705913650567

| username: 啦啦啦啦啦 | Original post link

SELECT * FROM mysql.tidb_mdl_view
Check if there is a metadata lock blocking.

| username: 路在何chu | Original post link

Check if there are any operation groups blocking this table.

| username: Jiawei | Original post link

Generally, it is not visible, and your data volume is not large, it shouldn’t be this slow. It is likely that it is locked.

| username: Hacker_0LElpqkb | Original post link

I checked and it shows up, but it’s not the table where I added the field.

| username: Hacker_0LElpqkb | Original post link

Does this count as a blockage? The last time a field was added to this table, it also got stuck and didn’t execute. After restarting the database, it was added successfully.

| username: 不想干活 | Original post link

Suspect there is a lock, check it out.

| username: Hacker_0LElpqkb | Original post link

If the online database is continuously updating or writing data, and writing data involves starting a transaction, will starting a transaction cause blocking?

| username: Hacker_0LElpqkb | Original post link

You can kill it.

| username: 这里介绍不了我 | Original post link

There is still a locking issue.

| username: dba远航 | Original post link

It is recommended to operate during your free time in the future.

| username: 江湖故人 | Original post link

This is indeed a blockage. Generally, you need to kill the session (session_id column).

| username: system | Original post link

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