ZUNION - Upstash Documentation

Use ZUNION to get every member that appears in at least one of the given sorted sets. <numkeys> states how many keys follow. A member present in several inputs gets the sum of its scores by default, which is how scores from different sources are combined; WEIGHTS scales each input before that, and AGGREGATE replaces the sum with MIN or MAX. WITHSCORES returns the computed scores. The result is computed on each call and not stored; use ZUNIONSTORE to keep it.

Syntax

ZUNION <numkeys> <key> [<key> ...]
  [WEIGHTS <weight> [<weight> ...]]
  [AGGREGATE SUM | MIN | MAX]
  [WITHSCORES]

Arguments

Argument	Required	Repeatable	Description
`<numkeys>`	Yes	No	Number of key arguments that follow.
`<key>`	Yes	Yes	Redis key targeted by the command.
`WEIGHTS <weight>`	No	Yes	Multiplier applied to each input key’s scores, in the order the keys were given.
`(AGGREGATE SUM \| MIN \| MAX)`	No	No	Under `AGGREGATE`, choose one form: `SUM`; `MIN`; `MAX`.
`WITHSCORES`	No	No	Include sorted-set scores.

Important points

numkeys must equal the number of key arguments that immediately follow it.
RESP2 represents floating-point reply values as bulk strings; RESP3 may use native double replies. Client libraries commonly decode either form to a language number.

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 members, or flat member/score array with `WITHSCORES`
RESP3	Array of members, or array of member/score pairs with `WITHSCORES`

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

ZUNION 1 my-key

@upstash/redis

import { Redis } from "@upstash/redis";

const redis = Redis.fromEnv();
const result = await redis.zunion(1, "my-key");
console.log(result);

upstash_redis

from upstash_redis import Redis

redis = Redis.from_env()
result = redis.zunion(["my-key"])
print(result)

ioredis

import Redis from "ioredis";

const redis = new Redis(process.env.REDIS_URL!);
const result = await redis.zunion("1", "my-key");
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.zUnion("my-key");
console.log(result);

redis-py

import os
import redis

client = redis.from_url(os.environ["REDIS_URL"])
result = client.zunion(["my-key"])
print(result)

go-redis

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.ZUnion(context.Background(), redis.ZStore{Keys: []string{"my-key"}}).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.zunion(new redis.clients.jedis.params.ZParams(), "my-key");
  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("ZUNION");
    command.arg("1");
    command.arg("my-key");
    let result: redis::Value = command.query(&mut connection)?;
    println!("{result:?}");
    Ok(())
}

​Syntax

​Arguments

​Important points

​Response

​Examples

Syntax

Arguments

Important points

Response

Examples