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

## Syntax

```redis
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
ZUNION 1 my-key
```

</Accordion>

<Accordion title="@upstash/redis" icon="node-js" iconType="brands">

```ts
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
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
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
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
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
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
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
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>