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include compatibility notice for tidb_remove_orderby_in_subquery #20139

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include compatibility notice for tidb_remove_orderby_in_subquery #20139

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d383e1b
include notice in release note 7.2
songrijie Mar 31, 2025
2914e76
Update release-7.2.0.md
songrijie Mar 31, 2025
c3eab57
Update release-7.2.0.md
hfxsd Apr 10, 2025
a150ffd
Update release-7.2.0.md
hfxsd Apr 11, 2025
39a09d0
Update release-7.2.0.md
hfxsd Apr 11, 2025
faf1ef1
Update release-7.2.0.md
hfxsd Apr 11, 2025
643bd44
Update releases/release-7.2.0.md
songrijie Apr 14, 2025
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3 changes: 2 additions & 1 deletion releases/release-7.2.0.md
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Expand Up @@ -173,6 +173,7 @@ TiDB 版本：7.2.0
### 行为变更

- 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)。
- 系统变量 [`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` 修改为 `ON`，即优化器改写会移除子查询中的 `ORDER BY` 子句，以避免不必要的排序操作。此变更可能造成 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的 `ORDER BY` 排序，如需严格保证最终结果的顺序应在外层查询添加 `ORDER BY`。如果你的应用依赖子查询排序，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该行为。

### 系统变量

Expand Down Expand Up @@ -330,4 +331,4 @@ TiDB 版本：7.2.0
- [L-maple](https://github.com/L-maple)
- [nyurik](https://github.com/nyurik)
- [SeigeC](https://github.com/SeigeC)
- [tangjingyu97](https://github.com/tangjingyu97)
- [tangjingyu97](https://github.com/tangjingyu97)
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