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Merge pull request #23735 from taosdata/mark/doc 

docs:add description for tmq
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docs/en/07-develop/07-tmq.mdx
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@ -23,7 +23,7 @@ By subscribing to a topic, a consumer can obtain the latest data in that topic i
To implement these features, TDengine indexes its write-ahead log (WAL) file for fast random access and provides configurable methods for replacing and retaining this file. You can define a retention period and size for this file. For information, see the CREATE DATABASE statement. In this way, the WAL file is transformed into a persistent storage engine that remembers the order in which events occur. However, note that configuring an overly long retention period for your WAL files makes database compression inefficient. TDengine then uses the WAL file instead of the time-series database as its storage engine for queries in the form of topics. TDengine reads the data from the WAL file; uses a unified query engine instance to perform filtering, transformations, and other operations; and finally pushes the data to consumers. To implement these features, TDengine indexes its write-ahead log (WAL) file for fast random access and provides configurable methods for replacing and retaining this file. You can define a retention period and size for this file. For information, see the CREATE DATABASE statement. In this way, the WAL file is transformed into a persistent storage engine that remembers the order in which events occur. However, note that configuring an overly long retention period for your WAL files makes database compression inefficient. TDengine then uses the WAL file instead of the time-series database as its storage engine for queries in the form of topics. TDengine reads the data from the WAL file; uses a unified query engine instance to perform filtering, transformations, and other operations; and finally pushes the data to consumers.
The following are some explanations about data subscription, which require some understanding of the architecture of TDengine and the use of various language linker interfaces. The following are some explanations about data subscription, which require some understanding of the architecture of TDengine and the use of various language linker interfaces（you can learn it when you need it）.
- A consumption group consumes all data under the same topic, and different consumption groups are independent of each other; - A consumption group consumes all data under the same topic, and different consumption groups are independent of each other;
- A consumption group consumes all vgroups of the same topic, which can be composed of multiple consumers, but a vgroup is only consumed by one consumer. If the number of consumers exceeds the number of vgroups, the excess consumers do not consume data; - A consumption group consumes all vgroups of the same topic, which can be composed of multiple consumers, but a vgroup is only consumed by one consumer. If the number of consumers exceeds the number of vgroups, the excess consumers do not consume data;
- On the server side, only one offset is saved for each vgroup, and the offsets for each vgroup are monotonically increasing, but not necessarily continuous. There is no correlation between the offsets of various vgroups; - On the server side, only one offset is saved for each vgroup, and the offsets for each vgroup are monotonically increasing, but not necessarily continuous. There is no correlation between the offsets of various vgroups;
@ -45,12 +45,13 @@ The following are some explanations about data subscription, which require some
This document does not provide any further introduction to the knowledge of message queues themselves. If you need to know more, please search for it yourself. This document does not provide any further introduction to the knowledge of message queues themselves. If you need to know more, please search for it yourself.
Note:
Starting from version 3.2.0.0, data subscription supports vnode migration and splitting. Starting from version 3.2.0.0, data subscription supports vnode migration and splitting.
Due to the dependence of data subscription on wal files, wal does not synchronize during vnode migration and splitting. Therefore, after migration or splitting, wal data that has not been consumed before cannot be consumed. So please ensure that all data has been consumed before proceeding with vnode migration or splitting, otherwise data loss may occur during consumption. Due to the dependence of data subscription on wal files, wal does not synchronize during vnode migration and splitting. Therefore, after migration or splitting, wal data that has not been consumed before cannot be consumed. So please ensure that all data has been consumed before proceeding with vnode migration or splitting, otherwise data loss may occur during consumption.
## Data Schema and API ## Data Schema and API
The related schemas and APIs in various languages are described as follows: The related schemas and APIs in various languages are described as follows(Note that the consumer structure is not thread safe. When using a consumer on one thread, do not close the consumer on another thread):
<Tabs defaultValue="java" groupId="lang"> <Tabs defaultValue="java" groupId="lang">
<TabItem value="c" label="C"> <TabItem value="c" label="C">

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docs/zh/07-develop/07-tmq.mdx
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@ -23,7 +23,7 @@ import CDemo from "./_sub_c.mdx";
为了实现上述功能，TDengine 会为 WAL (Write-Ahead-Log) 文件自动创建索引以支持快速随机访问，并提供了灵活可配置的文件切换与保留机制：用户可以按需指定 WAL 文件保留的时间以及大小（详见 create database 语句）。通过以上方式将 WAL 改造成了一个保留事件到达顺序的、可持久化的存储引擎（但由于 TSDB 具有远比 WAL 更高的压缩率，我们不推荐保留太长时间，一般来说，不超过几天）。 对于以 topic 形式创建的查询，TDengine 将对接 WAL 而不是 TSDB 作为其存储引擎。在消费时，TDengine 根据当前消费进度从 WAL 直接读取数据，并使用统一的查询引擎实现过滤、变换等操作，将数据推送给消费者。 为了实现上述功能，TDengine 会为 WAL (Write-Ahead-Log) 文件自动创建索引以支持快速随机访问，并提供了灵活可配置的文件切换与保留机制：用户可以按需指定 WAL 文件保留的时间以及大小（详见 create database 语句）。通过以上方式将 WAL 改造成了一个保留事件到达顺序的、可持久化的存储引擎（但由于 TSDB 具有远比 WAL 更高的压缩率，我们不推荐保留太长时间，一般来说，不超过几天）。 对于以 topic 形式创建的查询，TDengine 将对接 WAL 而不是 TSDB 作为其存储引擎。在消费时，TDengine 根据当前消费进度从 WAL 直接读取数据，并使用统一的查询引擎实现过滤、变换等操作，将数据推送给消费者。
下面为关于数据订阅的一些说明，需要对TDengine的架构有一些了解，结合各个语言链接器的接口使用。 下面为关于数据订阅的一些说明，需要对TDengine的架构有一些了解，结合各个语言链接器的接口使用。(可使用时再了解)
- 一个消费组消费同一个topic下的所有数据，不同消费组之间相互独立； - 一个消费组消费同一个topic下的所有数据，不同消费组之间相互独立；
- 一个消费组消费同一个topic所有的vgroup，消费组可由多个消费者组成，但一个vgroup仅被一个消费者消费，如果消费者数量超过了vgroup数量，多余的消费者不消费数据； - 一个消费组消费同一个topic所有的vgroup，消费组可由多个消费者组成，但一个vgroup仅被一个消费者消费，如果消费者数量超过了vgroup数量，多余的消费者不消费数据；
- 在服务端每个vgroup仅保存一个offset，每个vgroup的offset是单调递增的，但不一定连续。各个vgroup的offset之间没有关联； - 在服务端每个vgroup仅保存一个offset，每个vgroup的offset是单调递增的，但不一定连续。各个vgroup的offset之间没有关联；
@ -45,12 +45,13 @@ import CDemo from "./_sub_c.mdx";
本文档不对消息队列本身的知识做更多的介绍，如果需要了解，请自行搜索。 本文档不对消息队列本身的知识做更多的介绍，如果需要了解，请自行搜索。
说明：
从3.2.0.0版本开始，数据订阅支持vnode迁移和分裂。 从3.2.0.0版本开始，数据订阅支持vnode迁移和分裂。
由于数据订阅依赖wal文件，而在vnode迁移和分裂的过程中，wal并不会同步过去，所以迁移或分裂后，之前没消费完的wal数据后消费不到。所以请保证之前把数据全部消费完后，再进行vnode迁移或分裂，否则，消费会丢失数据。 由于数据订阅依赖wal文件，而在vnode迁移和分裂的过程中，wal并不会同步过去，所以迁移或分裂后，之前没消费完的wal数据后消费不到。所以请保证之前把数据全部消费完后，再进行vnode迁移或分裂，否则，消费会丢失数据。
## 主要数据结构和 API ## 主要数据结构和 API
不同语言下， TMQ 订阅相关的 API 及数据结构如下： 不同语言下， TMQ 订阅相关的 API 及数据结构如下（注意consumer结构不是线程安全的，在一个线程使用consumer时，不要在另一个线程close这个consumer）：
<Tabs defaultValue="java" groupId="lang"> <Tabs defaultValue="java" groupId="lang">
<TabItem value="c" label="C"> <TabItem value="c" label="C">