ddl: fix concurrent column type changes(with changing data) that cause schema and data inconsistencies (#31051)

[ti-srebot]

cherry-pick #31051 to release-5.3
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/31071

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/31071:release-5.3-4ca3b02c90b7

---

What problem does this PR solve?

Issue Number: close #31048

Problem Summary:

For column type changes, the column ID is changed if it is lossy.

If both sessions perform lossy column type changes((like modify column c int -> char)) simultaneously

1. Connection1: execute DDL1, it will change column ID (ID :1-> ID :2)

2. Connection2: execute DDL2. After DDL1 enters the DDL job queue and is not executed, then DDL2 enters the job queue.

3. After DDL1 is executed successfully, DDL2 considers that the column is not lossy(char -> char), so it does not change the column ID, which is the old id:1. So id:1 overwrites id:2.

After DDL2 is completed, the column ID is still the original id:1 instead of the correct id:2.

Because the column ID was changed incorrectly, the schema could not match the data, resulting in decode failure when reading data.

What is changed and how it works?

In step 3, we check that the ID of the modified column is the same as the ID of the original column.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix concurrent column type changes(with changing data) that cause schema and data inconsistencies.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AilinKid
• tangenta

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[ti-srebot]

/run-all-tests

[guo-shaoge]

/run-check_dev
/run-mysql-test

@zimulala please remember to merge this pr. A new version is about to release. Thanks!

[zimulala]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 7b7e1f7

[zimulala]

/run-check_dev

[zimulala]

/run-check_dev

[zimulala]

/run-check_dev

[zhouqiang-cl]

/merge

[zhouqiang-cl]

/merge

[zimulala]

/run-check_dev

[guo-shaoge]

/run-check_dev

[guo-shaoge]

/run-check_dev

[guo-shaoge]

/run-check_dev

[guo-shaoge]

/run-mysql-test

[zimulala]

/run-check_dev

[ti-chi-bot]

@ti-srebot: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.