docs: document arrow endpoint api

docs/user-guide/protocols/http.md

@@ -151,6 +151,44 @@ The response contains the following fields:
     - `rows`: The rows of the query result, where each row is an array containing the corresponding values of the columns in the schema.
 - `execution_time_ms`: The execution time of the statement in milliseconds.
 
+### Alternative formats
+
+In addition to the default JSON format, the HTTP API also allows you to
+customize output format by providing the `format` query parameter with following
+values:
+
+- `influxdb_v1`: [influxdb query
+  API](https://docs.influxdata.com/influxdb/v1/tools/api/#query-http-endpoint)
+  compatible format. Additional parameters:
+  - `epoch`: `[ns,u,µ,ms,s,m,h]`, returns epoch timestamps with the specified
+    precision
+- `csv`: output in comma separated values
+- `arrow`: [Arrow IPC
+  format](https://arrow.apache.org/docs/python/feather.html). Additional
+  parameters:
+  - `compression`: `zstd` or `lz4`, default: no compression
+- `table`: ASCII table format for console output
+
+Call the SQL API with `table` format as an example:
+
+```shell
+curl -X POST \
+  -H 'Authorization: Basic {{authorization if exists}}' \
+  -H 'Content-Type: application/x-www-form-urlencoded' \
+  -d "sql=SELECT * FROM monitor" \
+  http://localhost:4000/v1/sql?db=public&format=table
+```
+
+Output
+
+```
+┌─host────────┬─ts────────────┬─cpu─┬─memory─┐
+│ "127.0.0.1" │ 1667446797450 │ 0.1 │ 0.4    │
+│ "127.0.0.1" │ 1667446798450 │ 0.5 │ 0.2    │
+│ "127.0.0.2" │ 1667446798450 │ 0.2 │ 0.3    │
+└─────────────┴───────────────┴─────┴────────┘
+```
+
 ## POST PromQL Queries
 
 GreptimeDB also exposes an custom HTTP API for querying with PromQL, and returning

i18n/zh/docusaurus-plugin-content-docs/current/user-guide/protocols/http.md

@@ -152,6 +152,43 @@ curl -X POST \
     - `rows`：查询结果的行数据，每行是一个数组，包含 schema 中对应列的值。
 - `execution_time_ms`：该语句的执行时间，以毫秒为单位。
 
+### 其他输出格式
+
+
+除了默认的 JSON 格式外，通过指定 `format` 参数，HTTP API 还支持自定义以下输出格
+式：
+
+- `influxdb_v1`: [influxdb 查询接
+  口](https://docs.influxdata.com/influxdb/v1/tools/api/#query-http-endpoint)兼
+  容格式，支持额外参数：
+  - `epoch`: `[ns,u,µ,ms,s,m,h]`, 控制输出时间戳精度
+- `csv`: CSV 格式
+- `arrow`: [Arrow IPC 格式](https://arrow.apache.org/docs/python/feather.html).
+  支持额外的参数：
+  - `compression`: `zstd` or `lz4`, 默认不设置压缩
+- `table`: 用于终端数据的 ASCII 表格格式
+
+以输出 `table` 格式为例：
+
+```shell
+curl -X POST \
+  -H 'Authorization: Basic {{authorization if exists}}' \
+  -H 'Content-Type: application/x-www-form-urlencoded' \
+  -d "sql=SELECT * FROM monitor" \
+  http://localhost:4000/v1/sql?db=public&format=table
+```
+
+Output
+
+```
+┌─host────────┬─ts────────────┬─cpu─┬─memory─┐
+│ "127.0.0.1" │ 1667446797450 │ 0.1 │ 0.4    │
+│ "127.0.0.1" │ 1667446798450 │ 0.5 │ 0.2    │
+│ "127.0.0.2" │ 1667446798450 │ 0.2 │ 0.3    │
+└─────────────┴───────────────┴─────┴────────┘
+```
+
+
 ## POST PromQL 查询
 
 GreptimeDB 同样暴露了一个自己的 HTTP API 用于 PromQL 查询，即在当前的 API 路径 `/v1` 的后方拼接 `/promql`，如下示例：