> ## 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.

# SET

> Set string value.

Use `SET` to store a string value at a key, replacing whatever was there before, whatever its type.

By default the value is written unconditionally and the key's previous time to live is discarded. `KEEPTTL` preserves it, while `EX`, `PX`, `EXAT`, and `PXAT` attach a new lifetime in seconds or milliseconds, or an absolute deadline as a Unix timestamp. Setting the value and its expiration in one command is what keeps a key from ever existing without one.

The condition decides whether the write happens at all. `NX` writes only when the key does not exist, which combined with an expiration is the standard way to acquire a lock, and `XX` writes only when it already exists, which refreshes a value without creating it. `IFEQ` and `IFNE` compare the current value with the one you supply, and `IFDEQ` and `IFDNE` compare its digest as returned by [`DIGEST`](/docs/redis/commands/string/digest), so a large value can be checked without sending it; these conditional forms are implemented by this Upstash deployment and give you compare-and-set semantics in a single command. `IFEQ` and `IFDEQ` require the key to exist, while `IFNE` and `IFDNE` also write when it does not.

`GET` makes the reply the previous value instead of `OK`, which is how you swap a value and read what it replaced in one atomic step. When a condition prevents the write, the reply is null.

## Syntax

```redis theme={"system"}
SET <key> <value>
  [NX | XX | IFEQ <ifeq-value> | IFNE <ifne-value> |
    IFDEQ <ifdeq-digest> | IFDNE <ifdne-digest>]
  [GET]
  [EX <seconds> | PX <milliseconds> | EXAT <unix-time-seconds> |
    PXAT <unix-time-milliseconds> | KEEPTTL]
```

## Arguments

| Argument                                                                                                      | Required | Repeatable | Description                                                                                                                                                                                                                                                                                      |
| ------------------------------------------------------------------------------------------------------------- | -------- | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `<key>`                                                                                                       | Yes      | No         | Redis key targeted by the command.                                                                                                                                                                                                                                                               |
| `<value>`                                                                                                     | Yes      | No         | String value to store.                                                                                                                                                                                                                                                                           |
| `(NX \| XX \| IFEQ <ifeq-value> \| IFNE <ifne-value> \| IFDEQ <ifdeq-digest> \| IFDNE <ifdne-digest>)`        | No       | No         | Choose one form: `NX` (only when the key does not exist); `XX` (only when it already exists); `IFEQ` (only when the current value equals `<ifeq-value>`); `IFNE` (only when it differs); `IFDEQ` (only when the current value's digest equals `<ifdeq-digest>`); `IFDNE` (only when it differs). |
| `GET`                                                                                                         | No       | No         | Also return the previous value.                                                                                                                                                                                                                                                                  |
| `(EX <seconds> \| PX <milliseconds> \| EXAT <unix-time-seconds> \| PXAT <unix-time-milliseconds> \| KEEPTTL)` | No       | No         | Choose one form: `EX` (set a lifetime in seconds); `PX` (set a lifetime in milliseconds); `EXAT` (expire at a Unix timestamp in seconds); `PXAT` (expire at a Unix timestamp in milliseconds); `KEEPTTL` (preserve the existing key lifetime).                                                   |

## Important points

* `NX` and `XX` are mutually exclusive.
* Choose at most one expiration form and at most one condition. `GET` changes a successful reply from `OK` to the previous value.
* `IFEQ`/`IFNE` compare the current value; `IFDEQ`/`IFDNE` compare its digest. These conditional forms are implemented by this Upstash deployment.

## 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    | Simple string `OK`; with `GET`, the previous value as a bulk string, or Null bulk string or null array when the key did not exist or a condition failed |
| RESP3    | Simple string `OK`; with `GET`, the previous value as a bulk string, or Null when the key did not exist or a condition failed                           |

<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"}
    SET my-key value
    ```
  </Accordion>

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

    const redis = Redis.fromEnv();

    await redis.set("my-key", {my: "value"});
    ```
  </Accordion>

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

    redis = Redis.from_env()
    result = redis.set("my-key", "value")
    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.set("my-key", "value");
    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.set("my-key", "value");
    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.set("my-key", "value")
    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.Set(context.Background(), "my-key", "value", 0).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.set("my-key", "value");
      System.out.println(result);
    }
    ```
  </Accordion>

  <Accordion title="redis-rs" icon="rust" iconType="brands">
    ```rust theme={"system"}
    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.set("my-key", "value")?;
        println!("{result:?}");
        Ok(())
    }
    ```
  </Accordion>
</AccordionGroup>


## Related topics

- [SET](/docs/redis/sdks/ts/commands/string/set.md)
- [Set commands](/docs/redis/commands/set/overview.md)
- [JSON.SET](/docs/redis/commands/json/json-set.md)