include compatibility notice for tidb_remove_orderby_in_subquery #20139
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
[APPROVALNOTIFIER] This PR is NOT APPROVED This pull-request has been approved by: The full list of commands accepted by this bot can be found here.
Needs approval from an approver in each of these files:
Approvers can indicate their approval by writing |
ti-chi-bot
bot
added
missing-translation-status
15 tasks
|
/bot-review |
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=60&v=4){kind=small}
| @@ -174,6 +174,8 @@ TiDB 版本：7.2.0 | |||
|
|
|||
| - TiCDC 在处理 Update 事件时，如果事件的主键或者非空唯一索引的列值发生改变，则会将该条事件拆分为 Delete 和 Insert 两条事件。更多信息，请参考[用户文档](/ticdc/ticdc-split-update-behavior.md#含有单条-update-变更的事务拆分)。 | |||
|
|
|||
| - [`tidb_remove_orderby_in_subquery`](/system-variables.md#tidb_remove_orderby_in_subquery-从-v610-版本开始引入) 的默认值从 `OFF` 改为 `ON`，避免不必要的排序操作。这可能造成 SQL 输出不同的查询顺序。ISO/IEC SQL 标准并不要求查询结果遵循子查询 ORDER BY 排序，在外层查询中显式增加排序才能严格保证最终结果的顺序。依赖子查询排序的应用可以将此变量修改为 `OFF`，从旧版本升级的集群默认不会修改这个行为。 | |||
There was a problem hiding this comment.
该说明过于技术化且冗长，建议拆分为更易理解的短句，并明确说明升级影响和解决方案。
Suggested change
| - [`tidb_remove_orderby_in_subquery`](/system-variables.md#tidb_remove_orderby_in_subquery-从-v610-版本开始引入) 的默认值从 `OFF` 改为 `ON`，避免不必要的排序操作。这可能造成 SQL 输出不同的查询顺序。ISO/IEC SQL 标准并不要求查询结果遵循子查询 ORDER BY 排序，在外层查询中显式增加排序才能严格保证最终结果的顺序。依赖子查询排序的应用可以将此变量修改为 `OFF`，从旧版本升级的集群默认不会修改这个行为。 | |
| - [`tidb_remove_orderby_in_subquery`](/system-variables.md#tidb_remove_orderby_in_subquery-从-v610-版本开始引入) 的默认值从 `OFF` 改为 `ON` 以优化性能。此变更可能导致查询结果顺序与之前版本不同。根据 SQL 标准，子查询中的 ORDER BY 不保证最终结果顺序，如需严格排序应在外层查询添加 ORDER BY。升级集群不会自动修改此变量值，如需保持原行为请手动设置为 `OFF`。 |
|
✅ AI review completed, 1 comments generated. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
What is changed, added or deleted? (Required)
I got inquiries from customers. The change of default value for
tidb_remove_orderby_in_subquery(v7.2.0) would cause disordered outputs. Even though this is expected, we'd better include a notice in release notes.Which TiDB version(s) do your changes apply to? (Required)
Tips for choosing the affected version(s):
By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.
For details, see tips for choosing the affected versions (in Chinese).
What is the related PR or file link(s)?
Do your changes match any of the following descriptions?