zh,en: make the description clearer on how to use the configs

en/feature-online-ddl.md

@@ -52,7 +52,7 @@ In the task configuration file, `online-ddl` is at the same level of `name`. For
 ## ********* Basic configuration *********
 name: test                      # The name of the task. Should be globally unique.
 task-mode: all                  # The task mode. Can be set to `full`/`incremental`/`all`.
-shard-mode: "pessimistic"       # You need to configure this if it is a shard merge task. The "pessimistic" mode is used by default. After understanding the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
+shard-mode: "pessimistic"       # The shard merge mode. Optional modes are ""/"pessimistic"/"optimistic". The "" mode is used by default which means sharding DDL merge is disabled. If the task is a shard merge task, set it to the "pessimistic" mode. After understanding the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
 meta-schema: "dm_meta"          # The downstream database that stores the `meta` information.
 online-ddl: true                # Supports automatic processing of "gh-ost" and "pt" for the upstream database.
 online-ddl-scheme: "gh-ost"     # `online-ddl-scheme` will be deprecated in the future, so it is recommended to use `online-ddl`.

en/key-features.md

@@ -426,10 +426,10 @@ Currently, the shard merge feature is supported only in limited scenarios. For d
 
 ### Parameter configuration
 
-Set `is-sharding` to `true` in the task configuration file:
+Set `shard-mode` to `pessimistic` in the task configuration file:
 
 ```
-shard-mode: "pessimistic" # You need to configure this if it is a shard merge task. The "pessimistic" mode is used by default. After understanding the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
+shard-mode: "pessimistic" # The shard merge mode. Optional modes are ""/"pessimistic"/"optimistic". The "" mode is used by default which means sharding DDL merge is disabled. If the task is a shard merge task, set it to the "pessimistic" mode. After getting a deep understanding of the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
 ```
 
 ### Handle sharding DDL locks manually

en/task-configuration-file-full.md

@@ -24,7 +24,8 @@ The following is the task configuration file template which allows you to perfor
 ## ********* Basic configuration *********
 name: test                      # The name of the task. Should be globally unique.
 task-mode: all                  # The task mode. Can be set to `full`(only migrates full data)/`incremental`(replicates binlogs synchronously)/`all` (replicates both full data and incremental binlogs).
-shard-mode: "pessimistic"       # The shard merge mode. Optional modes are ""/"pessimistic"/"optimistic". The "" mode is used by default which means no specific mode is required. If the task is a shard merge task, set it to the "pessimistic" mode.
+is-sharding: true               # `is-sharding` has been deprecated since v2.0.0, so it is recommended to directly use `shard-mode`
+shard-mode: "pessimistic"       # The shard merge mode. Optional modes are ""/"pessimistic"/"optimistic". The "" mode is used by default which means sharding DDL merge is disabled. If the task is a shard merge task, set it to the "pessimistic" mode. 
                                 # After understanding the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
 meta-schema: "dm_meta"          # The downstream database that stores the `meta` information.
 timezone: "Asia/Shanghai"       # The timezone.

en/task-configuration-guide.md

@@ -181,7 +181,7 @@ The following example shows how to configure the task as a shard merge task:
 
 ## ********* Basic information *********
 name: test                      # The name of the task. Should be globally unique.
-shard-mode: "pessimistic"       # The shard-mode must be configured for a shard merge task. By default, use the "pessimistic" mode. After getting a deep understanding of the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
+shard-mode: "pessimistic"       # The shard merge mode. Optional modes are ""/"pessimistic"/"optimistic". The "" mode is used by default which means sharding DDL merge is disabled. If the task is a shard merge task, set it to the "pessimistic" mode. After getting a deep understanding of the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
 ```
 
 ## Other configurations
@@ -193,7 +193,7 @@ The following is an overall task configuration example of this document. The com
 
 ## ********* Basic configuration *********
 name: test                      # The name of the task. Should be globally unique.
-shard-mode: "pessimistic"       # The shard-mode must be configured for a shard merge task. By default, use the "pessimistic" mode. After getting a deep understanding of the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
+shard-mode: "pessimistic"       # The shard merge mode. Optional modes are ""/"pessimistic"/"optimistic". The "" mode is used by default which means sharding DDL merge is disabled. If the task is a shard merge task, set it to the "pessimistic" mode. After getting a deep understanding of the principles and restrictions of the "optimistic" mode, you can set it to the "optimistic" mode.
 task-mode: all                  # The task mode. Can be set to `full`(only migrates full data)/`incremental`(replicates binlog synchronously)/`all` (replicates both full and incremental binlogs).
 
 ## ******** Data source configuration **********

zh/faq.md

@@ -145,7 +145,7 @@ DM 在最后 `rename ghost_table to origin table` 的步骤会把内存的 DDL 
 
 ## DM v2.0.0 启动任务时出现 `fail to initial unit Sync of subtask`，报错信息的 `RawCause` 显示 `context deadline exceeded`
 
-该问题是 DM v2.0.0 版本的已知问题，在同步任务的表数目较多时触发，将在 v2.0.1 修复。使用 TiUP 部署的用户可以升级到开发版 nightly 解决该问题，或者访问 GitHub 上 [DM 仓库的 release 页面](https://github.com/pingcap/ticdc/releases)下载 v2.0.0-hotfix 版本手动替换可执行文件。
+该问题是 DM v2.0.0 的已知问题，在同步任务的表数目较多时触发，将在 v2.0.1 修复。使用 TiUP 部署的用户可以升级到开发版 nightly 解决该问题，或者访问 GitHub 上 [DM 仓库的 release 页面](https://github.com/pingcap/ticdc/releases)下载 v2.0.0-hotfix 版本手动替换可执行文件。
 
 ## DM 同步中报错 `duplicate entry`
 

zh/feature-online-ddl.md

@@ -55,7 +55,7 @@ online-ddl 在 task 配置文件里面与 name 同级，例子详见下面配置
 ## ********* 基本信息配置 *********
 name: test                      # 任务名称，需要全局唯一
 task-mode: all                  # 任务模式，可设为 "full"、"incremental"、"all"
-shard-mode: "pessimistic"       # 如果为分库分表合并任务则需要配置该项。默认使用悲观协调模式 "pessimistic"，在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
+shard-mode: "pessimistic"       # 默认值为 "" 即无需协调。如果为分库分表合并任务，请设置为悲观协调模式 "pessimistic"。在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
 meta-schema: "dm_meta"          # 下游储存 `meta` 信息的数据库
 online-ddl: true                # 支持上游使用 gh-ost 、pt 两种工具的自动处理
 online-ddl-scheme: "gh-ost"     # `online-ddl-scheme` 在未来将被弃用，建议使用 `online-ddl`

zh/key-features.md

@@ -449,7 +449,7 @@ DM 支持将上游 MySQL/MariaDB 各分库分表中的 DML、DDL 数据合并后
 在 task 的配置文件中设置：
 
 ```
-shard-mode: "pessimistic" # 如果为分库分表合并任务则需要配置该项。默认使用悲观协调模式 "pessimistic"，在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
+shard-mode: "pessimistic" # 默认值为 "" 即无需协调。如果为分库分表合并任务，请设置为悲观协调模式 "pessimistic"。在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
 ```
 
 ### 手动处理 Sharding DDL Lock

zh/task-configuration-file-full.md

@@ -24,7 +24,8 @@ aliases: ['/docs-cn/tidb-data-migration/dev/task-configuration-file-full/','/zh/
 ## ********* 基本信息配置 *********
 name: test                      # 任务名称，需要全局唯一
 task-mode: all                  # 任务模式，可设为 "full" - "只进行全量数据迁移"、"incremental" - "Binlog 实时同步"、"all" - "全量 + Binlog 实时同步"
-shard-mode: "pessimistic"       # 任务协调模式，可选的模式有 ""、"pessimistic、"optimistic"。默认使用 "" 即无需协调。如果是分库分表合并任务，请设置为悲观协调模式 "pessimistic"。
+is-sharding: true               # 该配置项从 DM v2.0.0 起弃用，其功能被 `shard-mode` 取代，建议使用 `shard-mode` 代替 `is-sharding`
+shard-mode: "pessimistic"       # 任务协调模式，可选的模式有 ""、"pessimistic、"optimistic"。默认值为 "" 即无需协调。如果是分库分表合并任务，请设置为悲观协调模式 "pessimistic"。
                                 # 在 v2.0.6 版本后乐观模式逐渐成熟，深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
 meta-schema: "dm_meta"          # 下游储存 `meta` 信息的数据库
 timezone: "Asia/Shanghai"       # 时区
@@ -39,10 +40,10 @@ target-database:                # 下游数据库实例配置
   user: "root"
   password: "/Q7B9DizNLLTTfiZHv9WoEAKamfpIUs="  # 推荐使用经 `dmctl encrypt` 加密后的密码
   max-allowed-packet: 67108864                  # 设置 DM 内部连接 TiDB 服务器时，TiDB 客户端的 "max_allowed_packet" 限制（即接受的最大数据包限制），单位为字节，默认 67108864 (64 MB)
-                                                # 该配置项从 DM v2.0.0 版本起弃用，DM 会自动获取连接 TiDB 的 "max_allowed_packet"
+                                                # 该配置项从 DM v2.0.0 起弃用，DM 会自动获取连接 TiDB 的 "max_allowed_packet"
   session:                                      # 设置 TiDB 的 session 变量，在 v1.0.6 版本引入。更多变量及解释参见 `https://docs.pingcap.com/zh/tidb/stable/system-variables`
-    sql_mode: "ANSI_QUOTES,NO_ZERO_IN_DATE,NO_ZERO_DATE" # 从 DM v2.0.0 版本起，如果配置文件中没有出现该项，DM 会自动从下游 TiDB 中获得适合用于 "sql_mode" 的值。手动配置该项具有更高优先级
-    tidb_skip_utf8_check: 1                              # 从 DM v2.0.0 版本起，如果配置文件中没有出现该项，DM 会自动从下游 TiDB 中获得适合用于 "tidb_skip_utf8_check" 的值。手动配置该项具有更高优先级
+    sql_mode: "ANSI_QUOTES,NO_ZERO_IN_DATE,NO_ZERO_DATE" # 从 DM v2.0.0 起，如果配置文件中没有出现该项，DM 会自动从下游 TiDB 中获得适合用于 "sql_mode" 的值。手动配置该项具有更高优先级
+    tidb_skip_utf8_check: 1                              # 从 DM v2.0.0 起，如果配置文件中没有出现该项，DM 会自动从下游 TiDB 中获得适合用于 "tidb_skip_utf8_check" 的值。手动配置该项具有更高优先级
     tidb_constraint_check_in_place: 0
   security:                       # 下游 TiDB TLS 相关配置
     ssl-ca: "/path/to/ca.pem"

zh/task-configuration-guide.md

@@ -162,7 +162,7 @@ target-database:       # 目标 TiDB 配置
 
 ## ********* 任务信息配置 *********
 name: test                      # 任务名称，需要全局唯一
-shard-mode: "pessimistic"       # 如果为分库分表合并任务则需要配置该项。默认使用悲观协调模式 "pessimistic"，在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
+shard-mode: "pessimistic"       # 默认值为 "" 即无需协调。如果为分库分表合并任务，请设置为悲观协调模式 "pessimistic"。在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
 ```
 
 ## 其他配置
@@ -174,7 +174,7 @@ shard-mode: "pessimistic"       # 如果为分库分表合并任务则需要配
 
 ## ********* 任务信息配置 *********
 name: test                      # 任务名称，需要全局唯一
-shard-mode: "pessimistic"       # 如果为分库分表合并任务则需要配置该项。默认使用悲观协调模式 "pessimistic"，在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
+shard-mode: "pessimistic"       # 默认值为 "" 即无需协调。如果为分库分表合并任务，请设置为悲观协调模式 "pessimistic"。在深入了解乐观协调模式的原理和使用限制后，也可以设置为乐观协调模式 "optimistic"
 task-mode: all                  # 任务模式，可设为 "full" - "只进行全量数据迁移"、"incremental" - "Binlog 实时同步"、"all" - "全量 + Binlog 迁移"
 
 ## ******** 数据源配置 **********