session vars used to control scanner

docs/query/query-variables/variables.md

@@ -699,6 +699,15 @@ Note that the comment must start with /*+ and can only follow the SELECT.
 
   Controls whether to extend variant column in desc table_name. The default value is false.
 
+* `enable_adaptive_pipeline_task_serial_read_on_limit`
+
+    When enabled, the pipeline task concurrency will be adjusted automatically. When the scan node has no filter conditions and the limit parameter is less than the number of rows specified in `adaptive_pipeline_task_serial_read_on_limit`, the parallelism of the scan will be set to 1.
+
+* `adaptive_pipeline_task_serial_read_on_limit`
+
+    When `enable_adaptive_pipeline_task_serial_read_on_limit` is enabled, the number of rows at which the parallelism of the scan will be set to 1. 
+    Default value is `10000`
+
 ***
 
 #### Supplementary instructions on statement execution timeout control

i18n/zh-CN/docusaurus-plugin-content-docs/current/query/query-variables/variables.md

@@ -687,6 +687,14 @@ try (Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:9030/
 
   是否展示 variant 的拆解列。默认为 false。
 
+* `enable_adaptive_pipeline_task_serial_read_on_limit`
+
+  开启后将会允许自动调整 pipeline task 的并发数。当 scan 节点没有过滤条件，且 limit 参数小于 `adaptive_pipeline_task_serial_read_on_limit` 中指定的行数时，scan 的并行度将会被设置为 1。
+
+* `adaptive_pipeline_task_serial_read_on_limit`
+
+  当 enable_adaptive_pipeline_task_serial_read_on_limit 开启时，scan 的并行度将会被设置为 1 的行数阈值。默认值是 `10000`。
+
 ***
 
 #### 关于语句执行超时控制的补充说明

i18n/zh-CN/docusaurus-plugin-content-docs/version-2.1/query/query-variables/variables.md

@@ -703,6 +703,14 @@ try (Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:9030/
 
   是否展示 variant 的拆解列。默认为 false。
 
+* `enable_adaptive_pipeline_task_serial_read_on_limit`
+
+  开启后将会允许自动调整 pipeline task 的并发数。当 scan 节点没有过滤条件，且 limit 参数小于 `adaptive_pipeline_task_serial_read_on_limit` 中指定的行数时，scan 的并行度将会被设置为 1。
+
+* `adaptive_pipeline_task_serial_read_on_limit`
+
+  当 enable_adaptive_pipeline_task_serial_read_on_limit 开启时，scan 的并行度将会被设置为 1 的行数阈值。默认值是 `10000`。
+
 ***
 
 #### 关于语句执行超时控制的补充说明

i18n/zh-CN/docusaurus-plugin-content-docs/version-3.0/query/query-variables/variables.md

@@ -687,6 +687,14 @@ try (Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:9030/
 
   是否展示 variant 的拆解列。默认为 false。
 
+* `enable_adaptive_pipeline_task_serial_read_on_limit`
+
+  开启后将会允许自动调整 pipeline task 的并发数。当 scan 节点没有过滤条件，且 limit 参数小于 `adaptive_pipeline_task_serial_read_on_limit` 中指定的行数时，scan 的并行度将会被设置为 1。
+
+* `adaptive_pipeline_task_serial_read_on_limit`
+
+  当 enable_adaptive_pipeline_task_serial_read_on_limit 开启时，scan 的并行度将会被设置为 1 的行数阈值。默认值是 `10000`。
+
 ***
 
 #### 关于语句执行超时控制的补充说明

versioned_docs/version-2.1/query/query-variables/variables.md

@@ -717,6 +717,15 @@ This feature is supported since the Apache Doris 2.0.2 version
 
   Controls whether to extend variant column in desc table_name. The default value is false.
 
+* `enable_adaptive_pipeline_task_serial_read_on_limit`
+
+    When enabled, the pipeline task concurrency will be adjusted automatically. When the scan node has no filter conditions and the limit parameter is less than the number of rows specified in `adaptive_pipeline_task_serial_read_on_limit`, the parallelism of the scan will be set to 1.
+
+* `adaptive_pipeline_task_serial_read_on_limit`
+
+    When `enable_adaptive_pipeline_task_serial_read_on_limit` is enabled, the number of rows at which the parallelism of the scan will be set to 1.
+    Default value is `10000`
+
 ***
 
 #### Supplementary instructions on statement execution timeout control

versioned_docs/version-3.0/query/query-variables/variables.md

@@ -699,6 +699,15 @@ Note that the comment must start with /*+ and can only follow the SELECT.
 
   Controls whether to extend variant column in desc table_name. The default value is false.
 
+* `enable_adaptive_pipeline_task_serial_read_on_limit`
+
+    When enabled, the pipeline task concurrency will be adjusted automatically. When the scan node has no filter conditions and the limit parameter is less than the number of rows specified in `adaptive_pipeline_task_serial_read_on_limit`, the parallelism of the scan will be set to 1.
+
+* `adaptive_pipeline_task_serial_read_on_limit`
+
+    When `enable_adaptive_pipeline_task_serial_read_on_limit` is enabled, the number of rows at which the parallelism of the scan will be set to 1.
+    Default value is `10000`
+
 ***
 
 #### Supplementary instructions on statement execution timeout control