docs: add TiDB Cloud Essential/Premium limitations and defaults for transaction variables#21645
Closed
ekexium wants to merge 5 commits into
Closed
docs: add TiDB Cloud Essential/Premium limitations and defaults for transaction variables#21645ekexium wants to merge 5 commits into
ekexium wants to merge 5 commits into
Conversation
|
Skipping CI for Draft Pull Request. |
ti-chi-bot
Bot
added
the
do-not-merge/work-in-progress
|
[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. DetailsNeeds approval from an approver in each of these files:Approvers can indicate their approval by writing |
ti-chi-bot
Bot
added
missing-translation-status
ti-chi-bot
Bot
removed
the
do-not-merge/work-in-progress
There was a problem hiding this comment.
Pull request overview
本 PR 为 TiDB v8.5 文档补充 TiDB X 在事务相关系统变量与配置项上的默认值差异与功能限制说明，避免用户在 TiDB X 上按普通 TiDB 的方式配置导致误解或配置被拒绝。
Changes:
- 在系统变量文档中补充 TiDB X 对
tidb_dml_type、tidb_replica_read的限制，以及tidb_txn_assertion_level的默认值差异。 - 在配置文件文档中补充
pessimistic-auto-commit在 TiDB X 的默认值差异说明。 - 在 Pipelined DML 与 Follower Read 专题文档中补充 TiDB X 不支持/受限的提示。
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| tidb-configuration-file.md | 补充 pessimistic-auto-commit 在 TiDB X 的默认值说明。 |
| system-variables.md | 补充 TiDB X 对 tidb_dml_type/tidb_replica_read 的限制与 tidb_txn_assertion_level 默认值差异。 |
| pipelined-dml.md | 在使用限制中注明 TiDB X 不支持 Pipelined DML 及其启用方式不可用。 |
| follower-read.md | 增加 TiDB X 仅支持 leader 读取模式的注意事项。 |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
| + 对于不存在冲突的场景，如果有大量自动提交事务（例如自动提交事务数量占业务数量的比例超过一半甚至更多，需要根据实际情况分析）且单个事务操作数据量较大的情况下，开启该配置项会造成性能回退。例如，自动提交的 `INSERT INTO SELECT` 语句。 | ||
| + 当 SESSION 级系统变量 [`tidb_dml_type`](/system-variables.md#tidb_dml_type-从-v800-版本开始引入) 设置为 `"bulk"` 时，在该 SESSION 中，该配置项的效果等同于设置为 `false`。 | ||
| + 默认值：false | ||
| + 在 TiDB X 中，该配置项的默认值为 true。普通 TiDB 的默认值仍为 false。 |
Comment on lines
+5670
to
+5674
| - 默认值：`FAST` | ||
| - 可选值：`OFF`，`FAST`，`STRICT` | ||
| - 这个变量用于设置 assertion 级别。assertion 是一项在事务提交过程中进行的数据索引一致性校验，它对正在写入的 key 是否存在进行检查。如果不符则说明数据索引不一致，会导致事务 abort。详见[数据索引一致性报错](/troubleshoot-data-inconsistency-errors.md)。 | ||
| - 对于新创建的 v6.0.0 及以上的集群，默认值为 `FAST`。对于升级版本的集群，如果升级前是低于 v6.0.0 的版本，升级后默认值为 `OFF`。 | ||
| - 在 TiDB X 中，该变量的默认值为 `STRICT`。 | ||
| - 对于普通 TiDB，新创建的 v6.0.0 及以上的集群默认值为 `FAST`。对于升级版本的集群，如果升级前是低于 v6.0.0 的版本，升级后默认值为 `OFF`。 |
|
|
||
| > **注意：** | ||
| > | ||
| > 在 TiDB X 中，不支持非 `leader` 读取模式，`tidb_replica_read` 仅可设置为 `leader`。如果设置为其他读取模式，设置会被拒绝。 |
ekexium
changed the title
ekexium
changed the title
qiancai
added
the
needs-cherry-pick-master
This file contains hidden or 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
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)
补充 TiDB Cloud Essential 和 TiDB Cloud Premium 在事务相关变量和配置项上的限制及默认值差异：
tidb_dml_type：TiDB Cloud Essential 和 TiDB Cloud Premium 只支持"standard"，不支持"bulk"，因此不能通过该变量启用 Pipelined DML。tidb_replica_read：TiDB Cloud Essential 和 TiDB Cloud Premium 只支持leader，其他读取模式会被拒绝。tidb_txn_assertion_level：TiDB Cloud Essential 和 TiDB Cloud Premium 的默认值为STRICT。pessimistic-auto-commit：TiDB Cloud Essential 和 TiDB Cloud Premium 的默认值为true，其他 TiDB 集群仍保持现有的false默认值。同时在 Pipelined DML 和 Follower Read 文档中补充对应限制。
Which TiDB version(s) do your changes apply to? (Required)
What is the related PR or file link(s)?
Do your changes match any of the following descriptions?
Validation
npx markdownlint-cli system-variables.md tidb-configuration-file.md pipelined-dml.md follower-read.md./scripts/verify-links.sh./scripts/verify-link-anchors.sh