EXISTS
Syntax
EXISTS key [key ...]
- Available since:
- Redis Open Source 1.0.0
- Time complexity:
- O(N) where N is the number of keys to check.
- ACL categories:
-
@keyspace,@read,@fast,
Returns if key exists.
The user should be aware that if the same existing key is mentioned in the arguments multiple times, it will be counted multiple times. So if somekey exists, EXISTS somekey somekey will return 2.
Examples
SET key1 "Hello"
EXISTS key1
EXISTS nosuchkey
SET key2 "World"
EXISTS key1 key2 nosuchkeyimport redis
r = redis.Redis(decode_responses=True)
res = r.set("key1", "Hello")
print(res)
# >>> True
res = r.set("key2", "World")
print(res)
# >>> True
res = r.delete("key1", "key2", "key3")
print(res)
# >>> 2
res = r.set("key1", "Hello")
print(res)
# >>> True
res = r.exists("key1")
print(res)
# >>> 1
res = r.exists("nosuchkey")
print(res)
# >>> 0
res = r.set("key2", "World")
print(res)
# >>> True
res = r.exists("key1", "key2", "nosuchkey")
print(res)
# >>> 2
res = r.set("mykey", "Hello")
print(res)
# >>> True
res = r.expire("mykey", 10)
print(res)
# >>> True
res = r.ttl("mykey")
print(res)
# >>> 10
res = r.set("mykey", "Hello World")
print(res)
# >>> True
res = r.ttl("mykey")
print(res)
# >>> -1
res = r.expire("mykey", 10, xx=True)
print(res)
# >>> False
res = r.ttl("mykey")
print(res)
# >>> -1
res = r.expire("mykey", 10, nx=True)
print(res)
# >>> True
res = r.ttl("mykey")
print(res)
# >>> 10
res = r.set("mykey", "Hello")
print(res)
# >>> True
res = r.expire("mykey", 10)
print(res)
# >>> True
res = r.ttl("mykey")
print(res)
# >>> 10
res = r.sadd("myset", *set([1, 2, 3, "foo", "foobar", "feelsgood"]))
print(res)
# >>> 6
res = list(r.sscan_iter("myset", match="f*"))
print(res)
# >>> ['foobar', 'foo', 'feelsgood']
cursor, key = r.scan(cursor=0, match='*11*')
print(cursor, key)
cursor, key = r.scan(cursor, match='*11*')
print(cursor, key)
cursor, key = r.scan(cursor, match='*11*')
print(cursor, key)
cursor, key = r.scan(cursor, match='*11*')
print(cursor, key)
cursor, keys = r.scan(cursor, match='*11*', count=1000)
print(cursor, keys)
res = r.geoadd("geokey", (0, 0, "value"))
print(res)
# >>> 1
res = r.zadd("zkey", {"value": 1000})
print(res)
# >>> 1
res = r.type("geokey")
print(res)
# >>> zset
res = r.type("zkey")
print(res)
# >>> zset
cursor, keys = r.scan(cursor=0, _type="zset")
print(keys)
# >>> ['zkey', 'geokey']
res = r.hset("myhash", mapping={"a": 1, "b": 2})
print(res)
# >>> 2
cursor, keys = r.hscan("myhash", 0)
print(keys)
# >>> {'a': '1', 'b': '2'}
cursor, keys = r.hscan("myhash", 0, no_values=True)
print(keys)
# >>> ['a', 'b']
import { createClient } from 'redis';
const client = createClient();
await client.connect().catch(console.error);
const delRes1 = await client.set('key1', 'Hello');
console.log(delRes1); // OK
const delRes2 = await client.set('key2', 'World');
console.log(delRes2); // OK
const delRes3 = await client.del(['key1', 'key2', 'key3']);
console.log(delRes3); // 2
const existsRes1 = await client.set('key1', 'Hello');
console.log(existsRes1); // OK
const existsRes2 = await client.exists('key1');
console.log(existsRes2); // 1
const existsRes3 = await client.exists('nosuchkey');
console.log(existsRes3); // 0
const existsRes4 = await client.set('key2', 'World');
console.log(existsRes4); // OK
const existsRes5 = await client.exists(['key1', 'key2', 'nosuchkey']);
console.log(existsRes5); // 2
const expireRes1 = await client.set('mykey', 'Hello');
console.log(expireRes1); // OK
const expireRes2 = await client.expire('mykey', 10);
console.log(expireRes2); // 1
const expireRes3 = await client.ttl('mykey');
console.log(expireRes3); // 10
const expireRes4 = await client.set('mykey', 'Hello World');
console.log(expireRes4); // OK
const expireRes5 = await client.ttl('mykey');
console.log(expireRes5); // -1
const expireRes6 = await client.expire('mykey', 10, "XX");
console.log(expireRes6); // 0
const expireRes7 = await client.ttl('mykey');
console.log(expireRes7); // -1
const expireRes8 = await client.expire('mykey', 10, "NX");
console.log(expireRes8); // 1
const expireRes9 = await client.ttl('mykey');
console.log(expireRes9); // 10
const ttlRes1 = await client.set('mykey', 'Hello');
console.log(ttlRes1); // OK
const ttlRes2 = await client.expire('mykey', 10);
console.log(ttlRes2); // 1
const ttlRes3 = await client.ttl('mykey');
console.log(ttlRes3); // 10
const scan1Res1 = await client.sAdd('myset', ['1', '2', '3', 'foo', 'foobar', 'feelsgood']);
console.log(scan1Res1); // 6
let scan1Res2 = [];
for await (const values of client.sScanIterator('myset', { MATCH: 'f*' })) {
scan1Res2 = scan1Res2.concat(values);
}
console.log(scan1Res2); // ['foo', 'foobar', 'feelsgood']
let cursor = '0';
let scanResult;
scanResult = await client.scan(cursor, { MATCH: '*11*' });
console.log(scanResult.cursor, scanResult.keys);
scanResult = await client.scan(scanResult.cursor, { MATCH: '*11*' });
console.log(scanResult.cursor, scanResult.keys);
scanResult = await client.scan(scanResult.cursor, { MATCH: '*11*' });
console.log(scanResult.cursor, scanResult.keys);
scanResult = await client.scan(scanResult.cursor, { MATCH: '*11*' });
console.log(scanResult.cursor, scanResult.keys);
scanResult = await client.scan(scanResult.cursor, { MATCH: '*11*', COUNT: 1000 });
console.log(scanResult.cursor, scanResult.keys);
const scan3Res1 = await client.geoAdd('geokey', { longitude: 0, latitude: 0, member: 'value' });
console.log(scan3Res1); // 1
const scan3Res2 = await client.zAdd('zkey', [{ score: 1000, value: 'value' }]);
console.log(scan3Res2); // 1
const scan3Res3 = await client.type('geokey');
console.log(scan3Res3); // zset
const scan3Res4 = await client.type('zkey');
console.log(scan3Res4); // zset
const scan3Res5 = await client.scan('0', { TYPE: 'zset' });
console.log(scan3Res5.keys); // ['zkey', 'geokey']
const scan4Res1 = await client.hSet('myhash', { a: 1, b: 2 });
console.log(scan4Res1); // 2
const scan4Res2 = await client.hScan('myhash', '0');
console.log(scan4Res2.entries); // [{field: 'a', value: '1'}, {field: 'b', value: '2'}]
const scan4Res3 = await client.hScan('myhash', '0', { COUNT: 10 });
const items = scan4Res3.entries.map((item) => item.field)
console.log(items); // ['a', 'b']
await client.close();
import redis.clients.jedis.UnifiedJedis;
import redis.clients.jedis.args.ExpiryOption;
import static org.junit.jupiter.api.Assertions.assertEquals;
public class CmdsGenericExample {
public void run() {
UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379");
String delResult1 = jedis.set("key1", "Hello");
System.out.println(delResult1); // >>> OK
String delResult2 = jedis.set("key2", "World");
System.out.println(delResult2); // >>> OK
long delResult3 = jedis.del("key1", "key2", "key3");
System.out.println(delResult3); // >>> 2
// Tests for 'del' step.
String existsResult1 = jedis.set("key1", "Hello");
System.out.println(existsResult1); // >>> OK
boolean existsResult2 = jedis.exists("key1");
System.out.println(existsResult2); // >>> true
boolean existsResult3 = jedis.exists("nosuchkey");
System.out.println(existsResult3); // >>> false
String existsResult4 = jedis.set("key2", "World");
System.out.println(existsResult4); // >>> OK
long existsResult5 = jedis.exists("key1", "key2", "nosuchkey");
System.out.println(existsResult5); // >>> 2
// Tests for 'exists' step.
String expireResult1 = jedis.set("mykey", "Hello");
System.out.println(expireResult1); // >>> OK
long expireResult2 = jedis.expire("mykey", 10);
System.out.println(expireResult2); // >>> 1
long expireResult3 = jedis.ttl("mykey");
System.out.println(expireResult3); // >>> 10
String expireResult4 = jedis.set("mykey", "Hello World");
System.out.println(expireResult4); // >>> OK
long expireResult5 = jedis.ttl("mykey");
System.out.println(expireResult5); // >>> -1
long expireResult6 = jedis.expire("mykey", 10, ExpiryOption.XX);
System.out.println(expireResult6); // >>> 0
long expireResult7 = jedis.ttl("mykey");
System.out.println(expireResult7); // >>> -1
long expireResult8 = jedis.expire("mykey", 10, ExpiryOption.NX);
System.out.println(expireResult8); // >>> 1
long expireResult9 = jedis.ttl("mykey");
System.out.println(expireResult9); // >>> 10
// Tests for 'expire' step.
String ttlResult1 = jedis.set("mykey", "Hello");
System.out.println(ttlResult1); // >>> OK
long ttlResult2 = jedis.expire("mykey", 10);
System.out.println(ttlResult2); // >>> 1
long ttlResult3 = jedis.ttl("mykey");
System.out.println(ttlResult3); // >>> 10
// Tests for 'ttl' step.
jedis.close();
}
}
package io.redis.examples.async;
import io.lettuce.core.*;
import io.lettuce.core.api.async.RedisAsyncCommands;
import io.lettuce.core.api.StatefulRedisConnection;
import java.util.concurrent.CompletableFuture;
public class CmdsGenericExample {
public void run() {
CompletableFuture<Void> existsExample = asyncCommands.set("key1", "Hello").thenCompose(res1 -> {
System.out.println(res1); // >>> OK
return asyncCommands.exists("key1");
}).thenCompose(res2 -> {
System.out.println(res2); // >>> 1
return asyncCommands.exists("nosuchkey");
}).thenCompose(res3 -> {
System.out.println(res3); // >>> 0
return asyncCommands.set("key2", "World");
}).thenCompose(res4 -> {
System.out.println(res4); // >>> OK
return asyncCommands.exists("key1", "key2", "nosuchkey");
}).thenAccept(res5 -> {
System.out.println(res5); // >>> 2
}).toCompletableFuture();
existsExample.join();
} finally {
redisClient.shutdown();
}
}
}
package io.redis.examples.reactive;
import io.lettuce.core.*;
import io.lettuce.core.api.reactive.RedisReactiveCommands;
import io.lettuce.core.api.StatefulRedisConnection;
import reactor.core.publisher.Mono;
public class CmdsGenericExample {
public void run() {
RedisClient redisClient = RedisClient.create("redis://localhost:6379");
try (StatefulRedisConnection<String, String> connection = redisClient.connect()) {
RedisReactiveCommands<String, String> reactiveCommands = connection.reactive();
Mono<Void> existsExample = reactiveCommands.set("key1", "Hello").doOnNext(res1 -> {
System.out.println(res1); // >>> OK
}).then(reactiveCommands.exists("key1")).doOnNext(res2 -> {
System.out.println(res2); // >>> 1
}).then(reactiveCommands.exists("nosuchkey")).doOnNext(res3 -> {
System.out.println(res3); // >>> 0
}).then(reactiveCommands.set("key2", "World")).doOnNext(res4 -> {
System.out.println(res4); // >>> OK
}).then(reactiveCommands.exists("key1", "key2", "nosuchkey")).doOnNext(res5 -> {
System.out.println(res5); // >>> 2
}).then();
Mono.when(existsExample).block();
} finally {
redisClient.shutdown();
}
}
}
package example_commands_test
import (
"context"
"fmt"
"math"
"time"
"github.com/redis/go-redis/v9"
)
func ExampleClient_del_cmd() {
ctx := context.Background()
rdb := redis.NewClient(&redis.Options{
Addr: "localhost:6379",
Password: "", // no password docs
DB: 0, // use default DB
})
delResult1, err := rdb.Set(ctx, "key1", "Hello", 0).Result()
if err != nil {
panic(err)
}
fmt.Println(delResult1) // >>> OK
delResult2, err := rdb.Set(ctx, "key2", "World", 0).Result()
if err != nil {
panic(err)
}
fmt.Println(delResult2) // >>> OK
delResult3, err := rdb.Del(ctx, "key1", "key2", "key3").Result()
if err != nil {
panic(err)
}
fmt.Println(delResult3) // >>> 2
}
func ExampleClient_exists_cmd() {
ctx := context.Background()
rdb := redis.NewClient(&redis.Options{
Addr: "localhost:6379",
Password: "", // no password docs
DB: 0, // use default DB
})
existsResult1, err := rdb.Set(ctx, "key1", "Hello", 0).Result()
if err != nil {
panic(err)
}
fmt.Println(existsResult1) // >>> OK
existsResult2, err := rdb.Exists(ctx, "key1").Result()
if err != nil {
panic(err)
}
fmt.Println(existsResult2) // >>> 1
existsResult3, err := rdb.Exists(ctx, "nosuchkey").Result()
if err != nil {
panic(err)
}
fmt.Println(existsResult3) // >>> 0
existsResult4, err := rdb.Set(ctx, "key2", "World", 0).Result()
if err != nil {
panic(err)
}
fmt.Println(existsResult4) // >>> OK
existsResult5, err := rdb.Exists(ctx, "key1", "key2", "nosuchkey").Result()
if err != nil {
panic(err)
}
fmt.Println(existsResult5) // >>> 2
}
func ExampleClient_expire_cmd() {
ctx := context.Background()
rdb := redis.NewClient(&redis.Options{
Addr: "localhost:6379",
Password: "", // no password docs
DB: 0, // use default DB
})
expireResult1, err := rdb.Set(ctx, "mykey", "Hello", 0).Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult1) // >>> OK
expireResult2, err := rdb.Expire(ctx, "mykey", 10*time.Second).Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult2) // >>> true
expireResult3, err := rdb.TTL(ctx, "mykey").Result()
if err != nil {
panic(err)
}
fmt.Println(math.Round(expireResult3.Seconds())) // >>> 10
expireResult4, err := rdb.Set(ctx, "mykey", "Hello World", 0).Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult4) // >>> OK
expireResult5, err := rdb.TTL(ctx, "mykey").Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult5) // >>> -1ns
expireResult6, err := rdb.ExpireXX(ctx, "mykey", 10*time.Second).Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult6) // >>> false
expireResult7, err := rdb.TTL(ctx, "mykey").Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult7) // >>> -1ns
expireResult8, err := rdb.ExpireNX(ctx, "mykey", 10*time.Second).Result()
if err != nil {
panic(err)
}
fmt.Println(expireResult8) // >>> true
expireResult9, err := rdb.TTL(ctx, "mykey").Result()
if err != nil {
panic(err)
}
fmt.Println(math.Round(expireResult9.Seconds())) // >>> 10
}
func ExampleClient_ttl_cmd() {
ctx := context.Background()
rdb := redis.NewClient(&redis.Options{
Addr: "localhost:6379",
Password: "", // no password docs
DB: 0, // use default DB
})
ttlResult1, err := rdb.Set(ctx, "mykey", "Hello", 10*time.Second).Result()
if err != nil {
panic(err)
}
fmt.Println(ttlResult1) // >>> OK
ttlResult2, err := rdb.TTL(ctx, "mykey").Result()
if err != nil {
panic(err)
}
fmt.Println(math.Round(ttlResult2.Seconds())) // >>> 10
}
using NRedisStack.Tests;
using StackExchange.Redis;
public class CmdsGenericExample
{
public void Run()
{
var muxer = ConnectionMultiplexer.Connect("localhost:6379");
var db = muxer.GetDatabase();
// Tests for 'copy' step.
bool delResult1 = db.StringSet("key1", "Hello");
Console.WriteLine(delResult1); // >>> true
bool delResult2 = db.StringSet("key2", "World");
Console.WriteLine(delResult2); // >>> true
long delResult3 = db.KeyDelete(["key1", "key2", "key3"]);
Console.WriteLine(delResult3); // >>> 2
// Tests for 'del' step.
// Tests for 'dump' step.
bool existsResult1 = db.StringSet("key1", "Hello");
Console.WriteLine(existsResult1); // >>> true
bool existsResult2 = db.KeyExists("key1");
Console.WriteLine(existsResult2); // >>> true
bool existsResult3 = db.KeyExists("nosuchkey");
Console.WriteLine(existsResult3); // >>> false
bool existsResult4 = db.StringSet("key2", "World");
Console.WriteLine(existsResult4); // >>> true
long existsResult5 = db.KeyExists(["key1", "key2", "nosuchkey"]);
Console.WriteLine(existsResult5); // >>> 2
// Tests for 'exists' step.
bool expireResult1 = db.StringSet("mykey", "Hello");
Console.WriteLine(expireResult1); // >>> true
bool expireResult2 = db.KeyExpire("mykey", new TimeSpan(0, 0, 10));
Console.WriteLine(expireResult2); // >>> true
TimeSpan expireResult3 = db.KeyTimeToLive("mykey") ?? TimeSpan.Zero;
Console.WriteLine(Math.Round(expireResult3.TotalSeconds)); // >>> 10
bool expireResult4 = db.StringSet("mykey", "Hello World");
Console.WriteLine(expireResult4); // >>> true
TimeSpan expireResult5 = db.KeyTimeToLive("mykey") ?? TimeSpan.Zero;
Console.WriteLine(Math.Round(expireResult5.TotalSeconds).ToString()); // >>> 0
bool expireResult6 = db.KeyExpire("mykey", new TimeSpan(0, 0, 10), ExpireWhen.HasExpiry);
Console.WriteLine(expireResult6); // >>> false
TimeSpan expireResult7 = db.KeyTimeToLive("mykey") ?? TimeSpan.Zero;
Console.WriteLine(Math.Round(expireResult7.TotalSeconds)); // >>> 0
bool expireResult8 = db.KeyExpire("mykey", new TimeSpan(0, 0, 10), ExpireWhen.HasNoExpiry);
Console.WriteLine(expireResult8); // >>> true
TimeSpan expireResult9 = db.KeyTimeToLive("mykey") ?? TimeSpan.Zero;
Console.WriteLine(Math.Round(expireResult9.TotalSeconds)); // >>> 10
// Tests for 'expire' step.
// Tests for 'expireat' step.
// Tests for 'expiretime' step.
// Tests for 'keys' step.
// Tests for 'migrate' step.
// Tests for 'move' step.
// Tests for 'object_encoding' step.
// Tests for 'object_freq' step.
// Tests for 'object_idletime' step.
// Tests for 'object_refcount' step.
// Tests for 'persist' step.
// Tests for 'pexpire' step.
// Tests for 'pexpireat' step.
// Tests for 'pexpiretime' step.
// Tests for 'pttl' step.
// Tests for 'randomkey' step.
// Tests for 'rename' step.
// Tests for 'renamenx' step.
// Tests for 'restore' step.
// Tests for 'scan1' step.
// Tests for 'scan2' step.
// Tests for 'scan3' step.
// Tests for 'scan4' step.
// Tests for 'sort' step.
// Tests for 'sort_ro' step.
// Tests for 'touch' step.
bool ttlResult1 = db.StringSet("mykey", "Hello");
Console.WriteLine(ttlResult1); // >>> true
bool ttlResult2 = db.KeyExpire("mykey", new TimeSpan(0, 0, 10));
Console.WriteLine(ttlResult2);
TimeSpan ttlResult3 = db.KeyTimeToLive("mykey") ?? TimeSpan.Zero;
string ttlRes = Math.Round(ttlResult3.TotalSeconds).ToString();
Console.WriteLine(Math.Round(ttlResult3.TotalSeconds)); // >>> 10
// Tests for 'ttl' step.
// Tests for 'type' step.
// Tests for 'unlink' step.
// Tests for 'wait' step.
// Tests for 'waitaof' step.
}
}
<?php
require_once 'vendor/autoload.php';
use Predis\Client as PredisClient;
class CmdsGenericTest
{
public function testCmdsGeneric() {
$r = new PredisClient([
'scheme' => 'tcp',
'host' => '127.0.0.1',
'port' => 6379,
'password' => '',
'database' => 0,
]);
$existsResult1 = $r->set('key1', 'Hello');
echo $existsResult1 . PHP_EOL; // >>> OK
$existsResult2 = $r->exists('key1');
echo $existsResult2 . PHP_EOL; // >>> 1
$existsResult3 = $r->exists('nosuchkey');
echo $existsResult3 . PHP_EOL; // >>> 0
$existsResult4 = $r->set('key2', 'World');
echo $existsResult4 . PHP_EOL; // >>> OK
$existsResult5 = $r->exists('key1', 'key2', 'nosuchkey');
echo $existsResult5 . PHP_EOL; // >>> 2
}
}
Give these commands a try in the interactive console:
Return information
Integer reply: the number of keys that exist from those specified as arguments.
History
- Starting with Redis version 3.0.3: Accepts multiple
keyarguments.