[WIP]: add v8.5.5 release notes #21195
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Dec 22, 2025
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Co-authored-by: zhaoshangzi <[email protected]> Co-authored-by: Frank945946 <[email protected]>
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Dec 24, 2025
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| 更多信息，请参考[用户文档](链接)。 | ||
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| * 按时间点恢复 (Point-in-time recovery, PITR) 支持从压缩后的日志备份中恢复，以加快恢复速度 [#56522](https://github.com/pingcap/tidb/issues/56522) @[YuJuncen](https://github.com/YuJuncen) **tw@lilin90** <!--2001--> |
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这条的中文目前是从 v9.0.0 复制过来的之前的描述，麻烦请按照 https://github.com/pingcap/docs/pull/22190/files 里最新的英文进行调整 @lilin90
qiancai
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Dec 24, 2025
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| 更多信息，请参考[用户文档](https://docs.pingcap.com/zh/tidb/v8.5/tikv-configuration-file#graceful-shutdown-timeout-从-v855-版本开始引入)。 | ||
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| * 提升进行中的日志备份与快照恢复的兼容性 [#58685](https://github.com/pingcap/tidb/issues/58685) @[BornChanger](https://github.com/BornChanger) **tw@lilin90** <!--2000--> |
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这条的中文目前是从 v9.0.0 复制过来的之前的描述，麻烦请按照 https://github.com/pingcap/docs/pull/22190/files 里最新的英文进行调整 @lilin90
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Co-authored-by: zhaoshangzi <[email protected]>
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Dec 25, 2025
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Dec 25, 2025
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Dec 25, 2025
releases/release-8.5.5.md
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| * 提示索引下推到TiKV提升查询性能 [#62575](https://github.com/pingcap/tidb/issues/62575) @[lcwangchao](https://github.com/lcwangchao) **tw@qiancai** <!--1899--> | ||
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| 通过hint INDEX_LOOKUP_PUSHDOWN(t1_name, idx1_name [, idx2_name ...]) 提示优化器将指定索引查询下推到TiKV，减少远程调用的次数，经过测试数据对比显示性能可提升约20%左右，最优可提升到40%。本特性一般建议结合表 affinity 属性使用，即表属性 AFFINITY="table" 或者 分区表属性 AFFINITY="partition" 。 |
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实际数据可能根据环境和负载不同有很大区别，这个数据目前是混合负载的结果，不光包含 pushdown
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通过hint INDEX_LOOKUP_PUSHDOWN(t1_name, idx1_name [, idx2_name ...]) 提示优化器将指定索引查询下推到TiKV，减少远程调用的次数，性能在理论上有提升，但具体提升比例需要结合业务场景实际测试。本特性一般建议结合表 affinity 属性使用，即表属性 AFFINITY="table" 或者 分区表属性 AFFINITY="partition" 。
qiancai
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Jan 9, 2026
Co-authored-by: Ruihao Chen <[email protected]>
qiancai
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Jan 9, 2026
qiancai
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Jan 9, 2026
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| - 优化了高基数指标 [#9357](https://github.com/tikv/pd/issues/9357) @[rleungx](https://github.com/rleungx) | ||
| - 优化时间戳推进和 Leader 选举的逻辑 [#9981](https://github.com/tikv/pd/issues/9981) @[bufferflies](https://github.com/bufferflies) | ||
| - 支持批量配置 TiKV 的 Store Limit [#9970](https://github.com/tikv/pd/issues/9970) @[bufferflies](https://github.com/bufferflies) |
qiancai
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Jan 9, 2026
qiancai
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Jan 9, 2026
| ### 系统变量 | ||
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| | 变量名 | 修改类型（包括新增/修改/删除） | 描述 | | ||
| |--------|------------------------------|------| |
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| |--------|------------------------------|------| | |
| |--------|------------------------------|------| | |
| | [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-从-v830-版本开始引入) | 修改 | 默认值从 `PREDICATE` 修改为 `ALL`，以提高统计信息完整性。 | |
Co-authored-by: Grace Cai <[email protected]>
Signed-off-by: tongjian <[email protected]>
Oreoxmt
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Jan 9, 2026
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| ### 性能 | ||
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| * 大幅提升特定有损 DDL 操作（例如 `BIGINT → INT`、`CHAR(120) → VARCHAR(60)`）的执行效率：在未发生数据截断的前提下，这类操作的执行耗时可从数小时缩短至分钟级、秒级甚至毫秒级，性能提升可达到数十倍至数十万倍 [#63366](https://github.com/pingcap/tidb/issues/63366) [@wjhuang2016](https://github.com/wjhuang2016), [@tangenta](https://github.com/tangenta), [@fzzf678](https://github.com/fzzf678)**tw@qiancai** <!--2292--> |
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| * 大幅提升特定有损 DDL 操作（例如 `BIGINT → INT`、`CHAR(120) → VARCHAR(60)`）的执行效率：在未发生数据截断的前提下，这类操作的执行耗时可从数小时缩短至分钟级、秒级甚至毫秒级，性能提升可达到数十倍至数十万倍 [#63366](https://github.com/pingcap/tidb/issues/63366) [@wjhuang2016](https://github.com/wjhuang2016), [@tangenta](https://github.com/tangenta), [@fzzf678](https://github.com/fzzf678)**tw@qiancai** <!--2292--> | |
| * 大幅提升特定有损 DDL 操作的执行效率：在未发生数据截断的前提下，`BIGINT → INT`、`CHAR(120) → VARCHAR(60)` 这类操作的执行耗时可从数小时缩短至分钟级、秒级甚至毫秒级，性能提升可达数十倍至数十万倍 [#63366](https://github.com/pingcap/tidb/issues/63366) [@wjhuang2016](https://github.com/wjhuang2016), [@tangenta](https://github.com/tangenta), [@fzzf678](https://github.com/fzzf678)**tw@qiancai** <!--2292--> |
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Co-authored-by: Aolin <[email protected]>
qiancai
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Jan 10, 2026
| - 修复 `plan replayer` 无法加载绑定的问题 [#64811](https://github.com/pingcap/tidb/issues/64811) @[hawkingrei](https://github.com/hawkingrei) | ||
| - 修复 `PointGet` 在有足够内存的情况下没有复用 chunk，导致不必要的内存分配的问题 [#63920](https://github.com/pingcap/tidb/issues/63920) @[hawkingrei](https://github.com/hawkingrei) | ||
| - 修复 `LogicalProjection.DeriveStats` 分配过多内存的问题 [#63810](https://github.com/pingcap/tidb/issues/63810) @[hawkingrei](https://github.com/hawkingrei) | ||
| - 修复当查询发生 panic 时，`plan replayer` 无法正常导出 (dump) 的问题 [#64835](https://github.com/pingcap/tidb/issues/64835) @[hawkingrei](https://github.com/hawkingrei) |
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| - 修复当查询发生 panic 时，`plan replayer` 无法正常导出 (dump) 的问题 [#64835](https://github.com/pingcap/tidb/issues/64835) @[hawkingrei](https://github.com/hawkingrei) | |
| - 修复当查询发生 panic 时，`plan replayer` 无法正常导出 (dump) 的问题 [#64835](https://github.com/pingcap/tidb/issues/64835) @[hawkingrei](https://github.com/hawkingrei) | |
| - 修复了在特定场景下，在 TTL 表的 `SHOW CREATE TABLE` 输出中属性顺序显示不正确的问题 [#64876](https://github.com/pingcap/tidb/issues/64876) @[YangKeao](https://github.com/YangKeao) | |
| - 修复了 TTL 任务超时时，其执行摘要信息为空的问题 [#61509](https://github.com/pingcap/tidb/issues/61509) @[YangKeao](https://github.com/YangKeao) |
qiancai
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Jan 10, 2026
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| - 优化了高基数指标，降低 PD 的内存占用和监控系统压力 [#9357](https://github.com/tikv/pd/issues/9357) @[rleungx](https://github.com/rleungx) | ||
| - 优化时间戳推进和 Leader 选举的逻辑 [#9981](https://github.com/tikv/pd/issues/9981) @[bufferflies](https://github.com/bufferflies) | ||
| - 支持批量配置 TiKV 的 Store Limit [#9970](https://github.com/tikv/pd/issues/9970) @[bufferflies](https://github.com/bufferflies) |
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| - 支持批量配置 TiKV 的 Store Limit [#9970](https://github.com/tikv/pd/issues/9970) @[bufferflies](https://github.com/bufferflies) | |
| - 支持按照存储引擎（TiKV 或 TiFlash) 批量配置 Store Limit [#9970](https://github.com/tikv/pd/issues/9970) @[bufferflies](https://github.com/bufferflies) |
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Jan 10, 2026
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What is changed, added or deleted? (Required)
As in the title, this PR adds the release note doc for v8.5.5.
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