# SUNION

```json metadata
{
  "schema_version": 2,
  "title": "SUNION",
  "description": "Returns the union of multiple sets.",
  "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"],
  "arguments": [{"display_text":"key","key_spec_index":0,"multiple":true,"name":"key","type":"key"}],
  "syntax_fmt": "SUNION key [key ...]",
  "complexity": "O(N) where N is the total number of elements in all given sets.",
  "group": "set",
  "command_flags": ["readonly"],
  "acl_categories": ["@read","@set","@slow"],
  "since": "1.0.0",
  "arity": -2,
  "key_specs": [{"RO":true,"access":true,"begin_search":{"spec":{"index":1},"type":"index"},"find_keys":{"spec":{"keystep":1,"lastkey":-1,"limit":0},"type":"range"}}],
  "tableOfContents": {"sections":[{"id":"required-arguments","title":"Required arguments"},{"id":"examples","title":"Examples"},{"id":"redis-software-and-redis-cloud-compatibility","title":"Redis Software and Redis Cloud compatibility"},{"id":"return-information","title":"Return information"},{"id":"see-also","title":"See also"}]}

,
  "codeExamples": []
}
```

> [!NOTE]
> This command's behavior varies in clustered Redis environments. See the [multi-key operations](https://redis.io/docs/latest/develop/using-commands/multi-key-operations) page for more information.


Returns the members of the set resulting from the union of all the given sets.

For example:

```
key1 = {a,b,c,d}
key2 = {c}
key3 = {a,c,e}
SUNION key1 key2 key3 = {a,b,c,d,e}
```

Keys that do not exist are considered to be empty sets.

## Required arguments

<details open><summary><code>key [key ...]</code></summary>

One or more set keys to union.

</details>

## Examples


redis> SADD key1 "a"
(integer) 1
redis> SADD key1 "b"
(integer) 1
redis> SADD key1 "c"
(integer) 1
redis> SADD key2 "c"
(integer) 1
redis> SADD key2 "d"
(integer) 1
redis> SADD key2 "e"
(integer) 1
redis> SUNION key1 key2
1) "a"
2) "c"
3) "d"
4) "e"
5) "b"


## Redis Software and Redis Cloud compatibility

| Redis<br />Software | Redis<br />Cloud | <span style="min-width: 9em; display: table-cell">Notes</span> |
|:----------------------|:-----------------|:------|
| <span title="Supported">&#x2705; Standard</span><br /><span title="Supported"><nobr>&#x2705; Active-Active</nobr></span> | <span title="Supported">&#x2705; Standard</span><br /><span title="Supported"><nobr>&#x2705; Active-Active</nobr></span> |  |

## Return information

**RESP2:**

[Array reply](../../develop/reference/protocol-spec#arrays): a list with members of the resulting set.

**RESP3:**

[Set reply](../../develop/reference/protocol-spec#sets): a set with the members of the resulting set.



## See also

[`SUNIONCARD`](https://redis.io/docs/latest/commands/sunioncard) | [`SUNIONSTORE`](https://redis.io/docs/latest/commands/sunionstore)