> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# ZUNION

> Get sorted set union.

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`](/docs/redis/commands/sorted-set/zunionstore) to keep it.

## Syntax

```redis theme={"system"}
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` |

<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={"system"}
    ZUNION 1 my-key
    ```
  </Accordion>

  <Accordion title="@upstash/redis" icon="node-js" iconType="brands">
    ```ts theme={"system"}
    import { Redis } from "@upstash/redis";

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

  <Accordion title="upstash_redis" icon="python" iconType="brands">
    ```python theme={"system"}
    from upstash_redis import Redis

    redis = Redis.from_env()
    result = redis.zunion(["my-key"])
    print(result)
    ```
  </Accordion>

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

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

  <Accordion title="node-redis" icon="node-js" iconType="brands">
    ```ts theme={"system"}
    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);
    ```
  </Accordion>

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

    client = redis.from_url(os.environ["REDIS_URL"])
    result = client.zunion(["my-key"])
    print(result)
    ```
  </Accordion>

  <Accordion title="go-redis" icon="golang" iconType="brands">
    ```go theme={"system"}
    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)
    }
    ```
  </Accordion>

  <Accordion title="jedis" icon="java" iconType="brands">
    ```java theme={"system"}
    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);
    }
    ```
  </Accordion>

  <Accordion title="redis-rs" icon="rust" iconType="brands">
    ```rust theme={"system"}
    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(())
    }
    ```
  </Accordion>
</AccordionGroup>


## Related topics

- [ZUNIONSTORE](/docs/redis/commands/sorted-set/zunionstore.md)
- [Overview](/docs/redis/sdks/py/commands/overview.md)