Clarify TiKV large-row limit in transaction restraints (#21830)#21834
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📝 WalkthroughWalkthrough事务限制文档新增 TiKV 单次写入请求大小限制，说明超出默认阈值时请求会被拒绝，并要求大单行记录同步调整 TiDB 与 TiKV 配置。 Changes事务限制文档
Estimated code review effort: 1 (Trivial) | ~2 minutes Possibly related PRs
Suggested labels: 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches🧪 Generate unit tests (beta)
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develop/dev-guide-transaction-restraints.md
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| - TiDB v4.0.10 及更高的 v4.0.x 版本、v5.0.0 及更高的版本可通过 tidb-server 配置项 [`performance.txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-从-v4010-和-v500-版本开始引入) 调整，低于 TiDB v4.0.10 的版本支持的单行容量为 6 MiB。 | ||
| - 从 v7.6.0 开始，你可以使用 [`tidb_txn_entry_size_limit`](/system-variables.md#tidb_txn_entry_size_limit-从-v760-版本开始引入) 系统变量动态修改该配置项的值。 | ||
| - 注意，TiKV 对单个写入请求的数据量大小也有限制。若单个写入请求的数据量超出 [`raftstore.raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size)（默认值为 8 MiB），TiKV 会拒绝处理该请求。当单行记录较大时，需要同时调整 TiDB 的 `tidb_txn_entry_size_limit` 和 TiKV 的 `raftstore.raft-entry-max-size`。 |
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🎯 Functional Correctness | 🟠 Major | ⚡ Quick win
兼容 v7.6.0 之前的版本
当前表述只要求调整 tidb_txn_entry_size_limit，但该系统变量从 v7.6.0 才引入；本 PR 覆盖的 7.5、7.1 和 6.5 用户无法按此说明配置 TiDB。请同时说明旧版本使用 performance.txn-entry-size-limit，并保留新版本的动态调整方式。
As per path instructions：对于 Markdown 文件，能够安全替换连续变更行时必须提供 GitHub 可提交建议块。
| - 注意，TiKV 对单个写入请求的数据量大小也有限制。若单个写入请求的数据量超出 [`raftstore.raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size)（默认值为 8 MiB），TiKV 会拒绝处理该请求。当单行记录较大时，需要同时调整 TiDB 的 `tidb_txn_entry_size_limit` 和 TiKV 的 `raftstore.raft-entry-max-size`。 | |
| - 注意，TiKV 对单个写入请求的数据量大小也有限制。若单个写入请求的数据量超出 [`raftstore.raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size)（默认值为 8 MiB），TiKV 会拒绝处理该请求。当单行记录较大时，需要同时调整 TiDB 的 [`performance.txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-从-v4010-和-v500-版本开始引入) 和 TiKV 的 [`raftstore.raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size)；从 v7.6.0 开始，也可以通过 [`tidb_txn_entry_size_limit`](/system-variables.md#tidb_txn_entry_size_limit-从-v760-版本开始引入) 动态调整 TiDB 的限制。 |
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This is an automated cherry-pick of #21830
What is changed, added or deleted? (Required)
Clarify in
develop/dev-guide-transaction-restraints.mdthat increasing the large-row limit in TiDB is not sufficient by itself. When a single write request exceeds TiKVraftstore.raft-entry-max-size, TiKV rejects the request, so users need to adjust the TiKV limit together with the TiDB row-size limit.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).
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