doc: remove experimental.enable.snapshot

docs/en/07-develop/07-tmq.mdx

@@ -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.
 
-Tips:The default data subscription is to consume data from the wal. If the wal is deleted, the consumed data will be incomplete. At this time, you can set the parameter experimental.snapshot.enable to true to obtain all data from the tsdb, but in this way, the consumption order of the data cannot be guaranteed. Therefore, it is recommended to set a reasonable retention policy for WAL based on your consumption situation to ensure that you can subscribe all data from WAL.
+Tips: Data subscription is to consume data from the wal. If some wal files are deleted according to WAL retention policy, the deleted data can't be consumed any more. So you need to set a reasonable value for parameter `WAL_RETENTION_PERIOD` or `WAL_RETENTION_SIZE` when creating the database and make sure your application consume the data in a timely way to make sure there is no data loss. This behavior is similar to Kafka and other widely used message queue products.
 
 ## Data Schema and API
 
@@ -294,7 +294,6 @@ You configure the following parameters when creating a consumer:
 |      `auto.offset.reset`       |  enum   | Initial offset for the consumer group                                     | Specify `earliest`, `latest`, or `none`(default) |
 |      `enable.auto.commit`      | boolean | Commit automatically; true: user application doesn't need to explicitly commit; false: user application need to handle commit by itself                                           | Default value is true                  |
 |   `auto.commit.interval.ms`    | integer | Interval for automatic commits, in milliseconds                           |
-| `experimental.snapshot.enable` | boolean | Specify whether to consume data in TSDB; true: both data in WAL and in TSDB can be consumed; false: only data in WAL can be consumed                   |     default value: false                                        |
 |     `msg.with.table.name`      | boolean | Specify whether to deserialize table names from messages                                 | default value: false
 
 The method of specifying these parameters depends on the language used:
@@ -312,7 +311,6 @@ tmq_conf_set(conf, "group.id", "cgrpName");
 tmq_conf_set(conf, "td.connect.user", "root");
 tmq_conf_set(conf, "td.connect.pass", "taosdata");
 tmq_conf_set(conf, "auto.offset.reset", "earliest");
-tmq_conf_set(conf, "experimental.snapshot.enable", "true");
 tmq_conf_set(conf, "msg.with.table.name", "true");
 tmq_conf_set_auto_commit_cb(conf, tmq_commit_cb_print, NULL);
 
@@ -368,7 +366,6 @@ conf := &tmq.ConfigMap{
  "td.connect.port":              "6030",
  "client.id":                    "test_tmq_c",
  "enable.auto.commit":           "false",
- "experimental.snapshot.enable": "true",
  "msg.with.table.name":          "true",
 }
 consumer, err := NewConsumer(conf)
@@ -416,7 +413,6 @@ Python programs use the following parameters:
 | `enable.auto.commit` | string | Commit automatically | pecify `true` or `false` |
 | `auto.commit.interval.ms` | string | Interval for automatic commits, in milliseconds | |
 | `auto.offset.reset` | string | Initial offset for the consumer group | Specify `earliest`, `latest`, or `none`(default) |
-| `experimental.snapshot.enable` | string | Specify whether it's allowed to consume messages from the WAL or from TSDB | Specify `true` or `false` |
 | `enable.heartbeat.background` | string | Backend heartbeat; if enabled, the consumer does not go offline even if it has not polled for a long time | Specify `true` or `false` |
 
 </TabItem>

docs/zh/07-develop/07-tmq.mdx

@@ -25,7 +25,8 @@ import CDemo from "./_sub_c.mdx";
 
 本文档不对消息队列本身的基础知识做介绍，如果需要了解，请自行搜索。
 
-注意：默认是从wal消费数据，如果wal被删除，消费到的数据会不全，此时可以将参数 experimental.snapshot.enable 设置为true，从tsdb获取全部数据，但是这样的话就不能保证数据的消费顺序。所以建议根据自己的消费情况合理的设置wal的保留策略，保证可以从wal里订阅到全部数据。
+注意：数据订阅是从 WAL 消费数据，如果一些 WAL 文件被基于 WAL 保留删除，则已经删除的 WAL 文件中的数据就无法再消费到。需要根据业务需要在创建数据库时合理设置 `WAL_RETENTION_PERIOD` 或 `WAL_RETENTION_SIZE` ，并确保应用及时消费数据，这样才不会产生数据丢失的现象。数据订阅的行为与 Kafka 等广泛使用的消息队列类产品的行为相似。
+
 ## 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：
@@ -293,7 +294,6 @@ CREATE TOPIC topic_name AS DATABASE db_name;
 |      `auto.offset.reset`       |  enum   | 消费组订阅的初始位置                                     | <br />`earliest`: default;从头开始订阅; <br/>`latest`: 仅从最新数据开始订阅; <br/>`none`: 没有提交的 offset 无法订阅 |
 |      `enable.auto.commit`      | boolean | 是否启用消费位点自动提交，true: 自动提交，客户端应用无需commit；false：客户端应用需要自行commit     | 默认值为 true                   |
 |   `auto.commit.interval.ms`    | integer | 消费记录自动提交消费位点时间间隔，单位为毫秒           | 默认值为 5000                                |
-| `experimental.snapshot.enable` | boolean | 是否允许从 TSDB 消费数据。当其关闭时，只能消费依据 WAL 保留策略仍然在WAL中的数据；当其打开时，除WAL中的数据以外，也能够消费已经从WAL中删除但落盘到TSDB中的数据                              | 实验功能，默认关闭                          |
 |     `msg.with.table.name`      | boolean | 是否允许从消息中解析表名, 不适用于列订阅（列订阅时可将 tbname 作为列写入 subquery 语句）               |默认关闭 |
 
 对于不同编程语言，其设置方式如下：
@@ -311,7 +311,6 @@ tmq_conf_set(conf, "group.id", "cgrpName");
 tmq_conf_set(conf, "td.connect.user", "root");
 tmq_conf_set(conf, "td.connect.pass", "taosdata");
 tmq_conf_set(conf, "auto.offset.reset", "earliest");
-tmq_conf_set(conf, "experimental.snapshot.enable", "true");
 tmq_conf_set(conf, "msg.with.table.name", "true");
 tmq_conf_set_auto_commit_cb(conf, tmq_commit_cb_print, NULL);
 
@@ -367,7 +366,6 @@ conf := &tmq.ConfigMap{
  "td.connect.port":              "6030",
  "client.id":                    "test_tmq_c",
  "enable.auto.commit":           "false",
- "experimental.snapshot.enable": "true",
  "msg.with.table.name":          "true",
 }
 consumer, err := NewConsumer(conf)
@@ -417,7 +415,6 @@ consumer = Consumer({"group.id": "local", "td.connect.ip": "127.0.0.1"})
 | `enable.auto.commit` | string | 启用自动提交 | 合法值：`true`, `false` |
 | `auto.commit.interval.ms` | string | 以毫秒为单位的自动提交时间间隔 | 默认值：5000 ms |
 | `auto.offset.reset` | string | 消费组订阅的初始位置 | 可选：`earliest`(default), `latest`, `none` |
-| `experimental.snapshot.enable` | string | 是否允许从 TSDB 消费数据 | 合法值：`true`, `false` |
 
 </TabItem>