ARLEN - Upstash Documentation

Use ARLEN to get the length of an array, meaning the highest occupied index plus one.

Because arrays are sparse, this is a measure of extent rather than of contents: writing a single value at index 1000 makes ARLEN report 1001 while ARCOUNT still reports 1. Read it as the exclusive upper bound for any full scan of the array.

A key that does not exist has length 0.

See the array command overview for the data model these commands share.

Syntax#

ARLEN <key>

Arguments#

Argument	Required	Repeatable	Description
`<key>`	Yes	No	Array key targeted by the command.

Important points#

A length above the signed 64-bit range is returned as a big number reply rather than an integer.

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	Integer, or bulk string when the length exceeds the signed 64-bit range
RESP3	Integer, or Big number when the length exceeds the signed 64-bit range

Note

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

Examples#

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

Redis CLI

ARLEN my-array

@upstash/redis

Note

This command is not supported yet in @upstash/redis.

upstash_redis

Note

This command is not supported yet in upstash_redis.

ioredis

import Redis from "ioredis";const redis = new Redis(process.env.REDIS_URL!);const result = await redis.arlen("my-array");console.log(result);

node-redis

import { createClient } from "redis";const client = await createClient({ url: process.env.REDIS_URL })  .on("error", console.error)  .connect();const result = await client.arLen("my-array");console.log(result);

redis-py

import osimport redisclient = redis.from_url(os.environ["REDIS_URL"])result = client.arlen("my-array")print(result)

go-redis

package mainimport (    "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.ARLen(context.Background(), "my-array").Result()    if err != nil {        panic(err)    }    fmt.Println(result)}

jedis

import java.net.URI;import redis.clients.jedis.Jedis;try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {  Object result = jedis.arlen("my-array");  System.out.println(result);}

redis-rs

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("ARLEN");    command.arg("my-array");    let result: redis::Value = command.query(&mut connection)?;    println!("{result:?}");    Ok(())}