ZUNIONSTORE - Upstash Documentation

Use ZUNIONSTORE to compute the union of sorted sets and store it in another key.

Members present in several inputs are scored by the sum of their scores by default, or by MIN or MAX when AGGREGATE is given, with WEIGHTS scaling each input first. The destination is overwritten if it exists and deleted when the union is empty, and the reply is the number of members stored.

Merging per-day or per-source rankings into a combined one, weighting them as you go, is the typical use: the destination is an ordinary sorted set that can then be paged with ZRANGE.

Syntax#

ZUNIONSTORE <destination> <numkeys> <key> [<key> ...]  [WEIGHTS <weight> [<weight> ...]]  [AGGREGATE SUM | MIN | MAX]

Arguments#

Argument	Required	Repeatable	Description
`<destination>`	Yes	No	Redis key used as destination.
`<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`.

Important points#

numkeys must equal the number of key arguments that immediately follow it.

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
RESP3	Integer

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

ZUNIONSTORE destination-key 1 my-key

@upstash/redis

import { Redis } from "@upstash/redis";const redis = Redis.fromEnv();await redis.zadd(    "key1",    { score: 1, member: "member1" },)await redis.zadd(    "key2",    { score: 1, member: "member1" },    { score: 2, member: "member2" },)const res = await redis.zunionstore("destination", 2, ["key1", "key2"]);console.log(res) // 2

upstash_redis

from upstash_redis import Redisredis = Redis.from_env()result = redis.zunionstore("destination-key", ["my-key"])print(result)

ioredis

import Redis from "ioredis";const redis = new Redis(process.env.REDIS_URL!);const result = await redis.zunionstore("destination-key", "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.zUnionStore("destination-key", "my-key");console.log(result);

redis-py

import osimport redisclient = redis.from_url(os.environ["REDIS_URL"])result = client.zunionstore("destination-key", ["my-key"])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.ZUnionStore(context.Background(), "destination-key", &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.zunionstore("destination-key", "my-key");  System.out.println(result);}

redis-rs

use redis::TypedCommands;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 result = connection.zunionstore("destination-key", &["my-key"])?;    println!("{result:?}");    Ok(())}