SET (original) (raw)

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Syntax

SET key value [NX | XX] [GET] [EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix-time-milliseconds | KEEPTTL]

Available since:

Redis Open Source 1.0.0

Time complexity:

O(1)

ACL categories:

@write, @string, @slow,

Set key to hold the string value. If key already holds a value, it is overwritten, regardless of its type. Any previous time to live associated with the key is discarded on successful SET operation.

Options

The SET command supports a set of options that modify its behavior:

Note: Since the SET command options can replace SETNX, SETEX, PSETEX, GETSET, it is possible that in future versions of Redis these commands will be deprecated and finally removed.

Examples

SET mykey "Hello" GET mykey

SET anotherkey "will expire in a minute" EX 60

Code examples

Python

"""
Code samples for data structure store quickstart pages:
    https://redis.io/docs/latest/develop/get-started/data-store/
"""

import redis

r = redis.Redis(host="localhost", port=6379, db=0, decode_responses=True)

res = r.set("bike:1", "Process 134")
print(res)
# >>> True

res = r.get("bike:1")
print(res)
# >>> "Process 134"

Node.js


import { createClient } from 'redis';

const client = createClient();

client.on('error', err => console.log('Redis Client Error', err));

await client.connect().catch(console.error);

await client.set('bike:1', 'Process 134');
const value = await client.get('bike:1');
console.log(value);
// returns 'Process 134'

await client.quit();

Java-Sync

package io.redis.examples;

import redis.clients.jedis.UnifiedJedis;


public class SetGetExample {

  public void run() {

    UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379");

    String status = jedis.set("bike:1", "Process 134");

    if ("OK".equals(status)) System.out.println("Successfully added a bike.");

    String value = jedis.get("bike:1");

    if (value != null) System.out.println("The name of the bike is: " + value + ".");


    jedis.close();
  }
}

Go

package example_commands_test

import (
    "context"
    "fmt"

    "github.com/redis/go-redis/v9"
)

func ExampleClient_Set_and_get() {
    ctx := context.Background()

    rdb := redis.NewClient(&redis.Options{
        Addr:     "localhost:6379",
        Password: "", // no password docs
        DB:       0,  // use default DB
    })


    err := rdb.Set(ctx, "bike:1", "Process 134", 0).Err()
    if err != nil {
        panic(err)
    }

    fmt.Println("OK")

    value, err := rdb.Get(ctx, "bike:1").Result()
    if err != nil {
        panic(err)
    }
    fmt.Printf("The name of the bike is %s", value)

}

C#


using NRedisStack.Tests;
using StackExchange.Redis;

public class SetGetExample
{
    public void run()
    {
        var muxer = ConnectionMultiplexer.Connect("localhost:6379");
        var db = muxer.GetDatabase();

        bool status = db.StringSet("bike:1", "Process 134");

        if (status)
            Console.WriteLine("Successfully added a bike.");

        var value = db.StringGet("bike:1");

        if (value.HasValue)
            Console.WriteLine("The name of the bike is: " + value + ".");

    }
}

Patterns

Note: The following pattern is discouraged in favor of the Redlock algorithm which is only a bit more complex to implement, but offers better guarantees and is fault tolerant.

The command SET resource-name anystring NX EX max-lock-time is a simple way to implement a locking system with Redis.

A client can acquire the lock if the above command returns OK (or retry after some time if the command returns Nil), and remove the lock just using DEL.

The lock will be auto-released after the expire time is reached.

It is possible to make this system more robust modifying the unlock schema as follows:

This avoids that a client will try to release the lock after the expire time deleting the key created by another client that acquired the lock later.

An example of unlock script would be similar to the following:

if redis.call("get",KEYS[1]) == ARGV[1]
then
    return redis.call("del",KEYS[1])
else
    return 0
end

The script should be called with EVAL ...script... 1 resource-name token-value

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