> ## Documentation Index
> Fetch the complete documentation index at: https://upstash-redis-1-18.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# ARSCAN

> Scan the populated slots of an array.

Use `ARSCAN` to list the occupied slots of an array in an index range.

Unlike [`ARGETRANGE`](/redis/commands/array/argetrange), which returns a null for every hole, `ARSCAN` skips empty slots and pairs each value with its index, so the cost of the reply tracks the data actually stored rather than the width of the range. That is what makes it usable over a sparse array whose indexes are, for instance, timestamps.

Results come back in ascending index order. `LIMIT` caps how many slots are returned, so a scan over a wide range can be walked in pages by using the last index of one page as the start of the next.

See the [array command overview](/redis/commands/array/overview) for the data model these commands share.

## Syntax

```redis theme={null}
ARSCAN <key> <start> <end> [LIMIT <limit>]
```

## Arguments

| Argument        | Required | Repeatable | Description                                                  |
| --------------- | -------- | ---------- | ------------------------------------------------------------ |
| `<key>`         | Yes      | No         | Array key targeted by the command.                           |
| `<start>`       | Yes      | No         | First index of the range, inclusive.                         |
| `<end>`         | Yes      | No         | Last index of the range, inclusive.                          |
| `LIMIT <limit>` | No       | No         | Maximum number of slots to return. Must be greater than `0`. |

## Important points

* Only occupied slots are returned, in ascending index order.
* `<start>` must not be greater than `<end>`; unlike [`ARGETRANGE`](/redis/commands/array/argetrange), `ARSCAN` does not reverse the range.

## Response

The reply reports the result of the operation. Error replies have the same shape in RESP2 and RESP3 and are surfaced as exceptions by the SDKs below.

| Protocol | Reply                                                    |
| -------- | -------------------------------------------------------- |
| RESP2    | Array of two-element arrays, each an index and its value |
| RESP3    | Array of two-element arrays, each an index and its value |

<Note>
  Client libraries often decode bulk strings, maps, sets, and numeric strings into language-native values. The table describes the Redis wire reply.
</Note>

## Examples

TCP examples use the TLS `REDIS_URL` from the Upstash console. REST examples use `UPSTASH_REDIS_REST_URL` and `UPSTASH_REDIS_REST_TOKEN`.

<AccordionGroup>
  <Accordion title="Redis CLI" icon="terminal">
    ```bash theme={null}
    ARSCAN my-array 0 1000 LIMIT 10
    ```
  </Accordion>

  <Accordion title="@upstash/redis" icon="node-js" iconType="brands">
    <Note>
      This command is not supported yet in `@upstash/redis`.
    </Note>
  </Accordion>

  <Accordion title="upstash_redis" icon="python" iconType="brands">
    <Note>
      This command is not supported yet in `upstash_redis`.
    </Note>
  </Accordion>

  <Accordion title="ioredis" icon="node-js" iconType="brands">
    ```ts theme={null}
    import Redis from "ioredis";

    const redis = new Redis(process.env.REDIS_URL!);
    const result = await redis.arscan("my-array", 0, 1000, "LIMIT", 10);
    console.log(result);
    ```
  </Accordion>

  <Accordion title="node-redis" icon="node-js" iconType="brands">
    ```ts theme={null}
    import { createClient } from "redis";

    const client = await createClient({ url: process.env.REDIS_URL })
      .on("error", console.error)
      .connect();
    const result = await client.arScan("my-array", 0, 1000, { LIMIT: 10 });
    console.log(result);
    ```
  </Accordion>

  <Accordion title="redis-py" icon="python" iconType="brands">
    ```python theme={null}
    import os
    import redis

    client = redis.from_url(os.environ["REDIS_URL"])
    result = client.arscan("my-array", 0, 1000, limit=10)
    print(result)
    ```
  </Accordion>

  <Accordion title="go-redis" icon="golang" iconType="brands">
    ```go theme={null}
    package main

    import (
        "context"
        "fmt"
        "os"

        "github.com/redis/go-redis/v9"
    )

    func main() {
        opts, err := redis.ParseURL(os.Getenv("REDIS_URL"))
        if err != nil {
            panic(err)
        }
        client := redis.NewClient(opts)
        result, err := client.ARScan(context.Background(), "my-array", 0, 1000, &redis.ARScanArgs{Limit: 10}).Result()
        if err != nil {
            panic(err)
        }
        fmt.Println(result)
    }
    ```
  </Accordion>

  <Accordion title="jedis" icon="java" iconType="brands">
    ```java theme={null}
    import java.net.URI;

    import redis.clients.jedis.Jedis;

    try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {
      Object result = jedis.arscan("my-array", 0, 1000, 10);
      System.out.println(result);
    }
    ```
  </Accordion>

  <Accordion title="redis-rs" icon="rust" iconType="brands">
    ```rust theme={null}
    fn main() -> redis::RedisResult<()> {
        let url = std::env::var("REDIS_URL").expect("REDIS_URL is not set");
        let client = redis::Client::open(url)?;
        let mut connection = client.get_connection()?;

        let mut command = redis::cmd("ARSCAN");
        command.arg("my-array");
        command.arg("0");
        command.arg("1000");
        command.arg("LIMIT");
        command.arg("10");
        let result: redis::Value = command.query(&mut connection)?;
        println!("{result:?}");
        Ok(())
    }
    ```
  </Accordion>
</AccordionGroup>