add documentation for tidb_enable_amend_pessimistic_txn. #4979

cfzjywxk · 2020-11-30T09:02:22Z

add documentation for tidb_enable_amend_pessimistic_txn.

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Add documentation about the system variable introduced by the new feature and the related project

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add documentation for tidb_enable_amend_pessimistic_txn.

jackysp

LGTM

zyguan

LGTM

It seems that the vars listed in this doc is in alphabetical order, thus we may need to prepose this one?

cfzjywxk · 2020-11-30T13:25:44Z

LGTM

It seems that the vars list in this doc is in alphabetical order, thus we may need to prepose this one?

Thanks for reminding, I didn't notice it but just follow the implemetation order.

you06 · 2020-12-01T02:57:45Z

system-variables.md

+
+- 作用域：SESSION | GLOBAL
+- 默认值: 0
+- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。开启该特性之后，在[悲观事务模式](/pessimistic-transaction.md)下，事务两阶段提交之前，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对于该事务进行 amend 操作修正该事务提交内容，使其和最新有效的 SCHEMA VERSION 保持一致，进而提交该事务而不返回 `Information schema is changed` 报错。该特性对于如下并发 DDL 变更生效：


Suggested change

- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。开启该特性之后，在[悲观事务模式](/pessimistic-transaction.md)下，事务两阶段提交之前，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对于该事务进行 amend 操作修正该事务提交内容，使其和最新有效的 SCHEMA VERSION 保持一致，进而提交该事务而不返回 `Information schema is changed` 报错。该特性对于如下并发 DDL 变更生效：

- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。开启该特性之后，在[悲观事务模式](/pessimistic-transaction.md)下，事务两阶段提交之前，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对于该事务进行 amend 操作修正该事务的提交内容，使其和最新有效的 SCHEMA VERSION 保持一致，进而成功提交该事务而不返回 `Information schema is changed` 报错。该特性对于如下并发 DDL 变更生效：

MyonKeminta · 2020-12-01T04:07:03Z

system-variables.md

+- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。开启该特性之后，在[悲观事务模式](/pessimistic-transaction.md)下，事务两阶段提交之前，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对于该事务进行 amend 操作修正该事务提交内容，使其和最新有效的 SCHEMA VERSION 保持一致，进而提交该事务而不返回 `Information schema is changed` 报错。该特性对于如下并发 DDL 变更生效：
+
+    - add/drop column 类型的 DDL 操作。
+    - modify/change column 类型的 DDL 操作。


I'm afraid we cannot support type changing for now

ti-srebot · 2020-12-03T04:08:43Z

@jackysp, @zyguan, @you06, @MyonKeminta, @coocood, PTAL.

you06

LGTM

ti-srebot · 2020-12-03T04:55:22Z

@you06, Thanks for your review. The bot only counts LGTMs from Reviewers and higher roles, but you're still welcome to leave your comments. See the corresponding SIG page for more information. Related SIG: docs(slack).

ti-srebot · 2020-12-05T04:56:43Z

@jackysp, @zyguan, @you06, @MyonKeminta, @coocood, PTAL.

ti-srebot · 2020-12-05T04:58:43Z

@cfzjywxk, please update your pull request.

ti-srebot · 2020-12-07T04:56:43Z

@jackysp, @zyguan, @you06, @MyonKeminta, @coocood, PTAL.

ti-srebot · 2020-12-07T04:58:42Z

@cfzjywxk, please update your pull request.

TomShawn · 2020-12-07T05:15:49Z

system-variables.md

+
+- 作用域：SESSION | GLOBAL
+- 默认值: 0
+- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。开启该特性之后，在[悲观事务模式](/pessimistic-transaction.md)下，事务两阶段提交之前，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对于该事务进行 amend 操作修正该事务的提交内容，使其和最新有效的 SCHEMA VERSION 保持一致，进而成功提交该事务而不返回 `Information schema is changed` 报错。该特性对于如下并发 DDL 变更生效：


Suggested change

- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。开启该特性之后，在[悲观事务模式](/pessimistic-transaction.md)下，事务两阶段提交之前，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对于该事务进行 amend 操作修正该事务的提交内容，使其和最新有效的 SCHEMA VERSION 保持一致，进而成功提交该事务而不返回 `Information schema is changed` 报错。该特性对于如下并发 DDL 变更生效：

- 这个变量用于控制是否开启 `AMEND TRANSACTION` 特性。在[悲观事务模式](/pessimistic-transaction.md)下开启该特性后，如果该事务相关的表存在并发 DDL 操作和 SCHEMA VERSION 变更，TiDB 会尝试对该事务进行 amend 操作，修正该事务的提交内容，使其和最新的有效 SCHEMA VERSION 保持一致，从而成功提交该事务而不返回 `Information schema is changed` 报错。该特性对以下并发 DDL 变更生效：

TomShawn · 2020-12-07T05:18:13Z

system-variables.md

+    - add/drop column 类型的 DDL 操作。
+    - modify/change column 类型的 DDL 操作，只对增大字段长度生效。
+    - add/drop index 类型的 DDL 操作，且操作的索引列不是在事务开启之后新创建。


Suggested change

- add/drop column 类型的 DDL 操作。

- modify/change column 类型的 DDL 操作，只对增大字段长度生效。

- add/drop index 类型的 DDL 操作，且操作的索引列不是在事务开启之后新创建。

- `ADD COLUMN` 或 `DROP COLUMN` 类型的 DDL 操作。

- `MODIFY COLUMN` 或 `CHANGE COLUMN` 类型的 DDL 操作，且只对增大字段长度的操作生效。

- `ADD INDEX` 或 `DROP INDEX` 类型的 DDL 操作，且操作的索引列须在事务开启之前创建。

TomShawn · 2020-12-07T05:20:37Z

system-variables.md

+    - modify/change column 类型的 DDL 操作，只对增大字段长度生效。
+    - add/drop index 类型的 DDL 操作，且操作的索引列不是在事务开启之后新创建。
+
+目前该特性可能造成事务语义的变化，且与 TiDB Binlog 存在部分兼容的场景，可以参考[事务语义行为区别](https://github.com/pingcap/tidb/issues/21069)和[与 Binlog 兼容问题汇总](https://github.com/pingcap/tidb/issues/20996)了解更多关于该特性的使用注意事项。


Suggested change

目前该特性可能造成事务语义的变化，且与 TiDB Binlog 存在部分兼容的场景，可以参考[事务语义行为区别](https://github.com/pingcap/tidb/issues/21069)和[与 Binlog 兼容问题汇总](https://github.com/pingcap/tidb/issues/20996)了解更多关于该特性的使用注意事项。

目前该特性可能造成事务语义的变化，且与 TiDB Binlog 存在部分不兼容的场景，可以参考[事务语义行为区别](https://github.com/pingcap/tidb/issues/21069)和[与 TiDB Binlog 兼容问题汇总](https://github.com/pingcap/tidb/issues/20996)了解更多关于该特性的使用注意事项。

TomShawn · 2020-12-07T05:24:39Z

@cfzjywxk I tried to refine the language in my comments. PTAL whether they are technically correct, thanks!

ti-srebot · 2020-12-09T05:24:43Z

@jackysp, @zyguan, @you06, @MyonKeminta, @TomShawn, @coocood, PTAL.

ti-srebot · 2020-12-09T05:24:50Z

@cfzjywxk, please update your pull request.

Address comments

TomShawn

LGTM

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

ti-srebot · 2020-12-10T10:07:44Z

cherry pick to release-4.0 in PR #5075

* cherry pick #4979 to release-4.0 Signed-off-by: ti-srebot <ti-srebot@pingcap.com> * Apply suggestions from code review Co-authored-by: cfzjywxk <lsswxr@163.com> Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>

Update system-variables.md

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add documentation for tidb_enable_amend_pessimistic_txn.

TomShawn self-assigned this Nov 30, 2020

TomShawn added needs-cherry-pick-4.0 size/medium Changes of a medium size. status/PTAL This PR is ready for reviewing. translation/doing This PR’s assignee is translating this PR. v5.0 This PR/issue applies to TiDB v5.0 labels Nov 30, 2020

TomShawn requested review from coocood, jackysp, you06, MyonKeminta and zyguan November 30, 2020 11:11

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Update system-variables.md

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TomShawn added status/PTAL This PR is ready for reviewing. and removed status/require-change Needs the author to address comments. labels Dec 2, 2020

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Merge branch 'master' into system-variable-master-amend

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Merge branch 'master' into system-variable-master-amend

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TomShawn added status/require-change Needs the author to address comments. and removed status/PTAL This PR is ready for reviewing. labels Dec 7, 2020

Update system-variables.md

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Address comments

cfzjywxk requested a review from TomShawn December 10, 2020 09:56

Merge branch 'master' into system-variable-master-amend

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ti-srebot removed the status/LGT1 Indicates that a PR has LGTM 1. label Dec 10, 2020

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ti-srebot added the status/LGT2 Indicates that a PR has LGTM 2. label Dec 10, 2020

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TomShawn merged commit de1c82c into pingcap:master Dec 10, 2020

ti-srebot pushed a commit to ti-srebot/docs-cn that referenced this pull request Dec 10, 2020

cherry pick pingcap#4979 to release-4.0

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Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

ti-srebot mentioned this pull request Dec 10, 2020

add documentation for tidb_enable_amend_pessimistic_txn. (#4979) #5075

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add a new system variable tidb_enable_amend_pessimistic_txn pingcap/docs#4411

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add a new system variable tidb_enable_amend_pessimistic_txn (#4411) pingcap/docs#4419

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TomShawn added translation/done This PR has been translated from English into Chinese and updated to pingcap/docs-cn in a PR. and removed translation/doing This PR’s assignee is translating this PR. labels Dec 16, 2020

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add documentation for tidb_enable_amend_pessimistic_txn. #4979

add documentation for tidb_enable_amend_pessimistic_txn. #4979

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	目前该特性可能造成事务语义的变化，且与 TiDB Binlog 存在部分兼容的场景，可以参考[事务语义行为区别](https://github.com/pingcap/tidb/issues/21069)和[与 Binlog 兼容问题汇总](https://github.com/pingcap/tidb/issues/20996)了解更多关于该特性的使用注意事项。
	目前该特性可能造成事务语义的变化，且与 TiDB Binlog 存在部分不兼容的场景，可以参考[事务语义行为区别](https://github.com/pingcap/tidb/issues/21069)和[与 TiDB Binlog 兼容问题汇总](https://github.com/pingcap/tidb/issues/20996)了解更多关于该特性的使用注意事项。

add documentation for tidb_enable_amend_pessimistic_txn. #4979

add documentation for tidb_enable_amend_pessimistic_txn. #4979

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cfzjywxk commented Nov 30, 2020

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