docs: the default selector changed

docs/contributor-guide/metasrv/selector.md

@@ -10,30 +10,33 @@ There is a specific scenario in `Metasrv` service. When a request to create a ta
 
 ## Selector Type
 
-Currently, there are two types of `Selector` available in the `Metasrv` service: `LeasebasedSelector` and `LoadBasedSelector`.
+The `Metasrv` service currently offers the following types of `Selectors`:
 
-### LeasebasedSelector [not recommended]
+### LeasebasedSelector
 
-`LeasebasedSelector` is just a simple implementation of `Selector`, but **it is not recommended**.
-
-It shuffles available `Datanode`s, and returns the list.
+`LeasebasedSelector` randomly selects from all available (in lease) `Datanode`s, its characteristic is simplicity and fast.
 
 ### LoadBasedSelector
 
-`LoadBasedSelector` is another implementation of the `Selector`.
+The `LoadBasedSelector` load value is determined by the number of regions on each `Datanode`, fewer regions indicate lower load, and `LoadBasedSelector` prioritizes selecting low-load `Datanodes`.
 
-It sorts available `Datanode`s according to the load, and returns a sorted list of these `Datanode`s.
+### RoundRobinSelector [default]
+`RoundRobinSelector` selects `Datanode`s in a round-robin fashion. It is recommended and the default option in most cases. If you're unsure which to choose, it's usually the right choice.
 
 ## Configuration
 
-You can configure the `Selector` when starting the `Metasrv` service, with the default being `LoadBasedSelector`.
+You can configure the `Selector` by its name when starting the `Metasrv` service.
+
+- LeasebasedSelector: `lease_based` or `LeaseBased`
+- LoadBasedSelector: `load_based` or `LoadBased`
+- RoundRobinSelector: `round_robin` or `RoundRobin`
 
 For example:
 
 ```shell
-cargo run -- metasrv start --selector load_based
+cargo run -- metasrv start --selector round_robin
 ```
 
 ```shell
-cargo run -- metasrv start --selector lease_based
+cargo run -- metasrv start --selector RoundRobin
 ```

i18n/zh/docusaurus-plugin-content-docs/current/contributor-guide/metasrv/selector.md

@@ -10,30 +10,33 @@
 
 ## Selector 类型
 
-目前，在 `Metasrv` 中有两种类型的 `Selector` 可用：`LeasebasedSelector` 和 `LoadBasedSelector`。
+`Metasrv` 目前提供以下几种类型的 `Selectors`:
 
-### LeasebasedSelector [不推荐]
+### LeasebasedSelector
 
-`LeasebasedSelector` 只是 `Selector` 的一个简单实现，但并不推荐。
-
-它会对可用的 `Datanode`s 进行随机排序，然后返回列表。
+`LeasebasedSelector` 从所有可用的（也就是在租约期间内）`Datanode` 中随机选择，其特点是简单和快速。
 
 ### LoadBasedSelector
 
-`LoadBasedSelector` 是 `Selector` 的另一种实现。
+`LoadBasedSelector` 按照负载来选择，负载值则由每个 `Datanode` 上的 region 数量决定，较少的 region 表示较低的负载，`LoadBasedSelector` 优先选择低负载的 `Datanode`。
 
-它根据负载对可用的 `Datanode`s 进行排序，然后返回一个已排序的 `Datanode` 列表。
+### RoundRobinSelector [默认选项]
+`RoundRobinSelector` 以轮询的方式选择 `Datanode`。在大多数情况下，这是默认的且推荐的选项。如果你不确定选择哪个，通常它就是正确的选择。
 
 ## 配置
 
-在启动 `Metasrv` 服务时，您可以配置 `Selector`，默认值是 `LoadBasedSelector`。
+您可以在启动 `Metasrv` 服务时通过名称配置 `Selector`。
+
+- LeasebasedSelector: `lease_based` 或 `LeaseBased`
+- LoadBasedSelector: `load_based` 或 `LoadBased`
+- RoundRobinSelector: `round_robin` 或 `RoundRobin`
 
 例如：
 
 ```shell
-cargo run -- metasrv start --selector load_based
+cargo run -- metasrv start --selector round_robin
 ```
 
 ```shell
-cargo run -- metasrv start --selector lease_based
+cargo run -- metasrv start --selector RoundRobin
 ```