How to get all Keys from Redis using redis template

Question

I have been stuck with this problem with quite some time.I want to get keys from redis using redis template. I tried this.redistemplate.keys(\"*\"); but this doesn\'t fetch

Answer 1

It did work, but seems not recommended? Because we can't use Keys command in production. I assume RedisTemplate.getConnectionFactory().getConnection().keys is calling redis Keys command. What are the alternatives?

Answer 2

Avoid to use keys command. It may ruin performance when it is executed against large databases.

You should use scan command instead. Here is how you can do it:

RedisConnection redisConnection = null;
try {
    redisConnection = redisTemplate.getConnectionFactory().getConnection();
    ScanOptions options = ScanOptions.scanOptions().match("myKey*").count(100).build();

    Cursor c = redisConnection.scan(options);
    while (c.hasNext()) {
        logger.info(new String((byte[]) c.next()));
    }
} finally {
    redisConnection.close(); //Ensure closing this connection.
}

or do it much simplier with Redisson Redis Java client:

Iterable<String> keysIterator = redisson.getKeys().getKeysByPattern("test*", 100);
for (String key : keysIterator) {
    logger.info(key);
}

Answer 3

I was using redisTemplate.keys(), but it was not working. So I used jedis, it worked. The following is the code that I used.

    Jedis jedis = new Jedis("localhost", 6379);
    Set<String> keys = jedis.keys("*".getBytes());
    for (String key : keys) {
        // do something
    } // for

Answer 4

Solution can be like this

String pattern = "abc"+"*";
Set<String> keys = jedis.keys(pattern);
for (String key : keys) {
    jedis.keys(key);
} 

Or you can use jedis.hscan() and ScanParams instead.

Answer 5

I just consolidated the answers, we have seen here.

Here are the two ways of getting keys from Redis, when we use RedisTemplate.

1. Directly from RedisTemplate

Set<String> redisKeys = template.keys("samplekey*"));
// Store the keys in a List
List<String> keysList = new ArrayList<>();
Iterator<String> it = redisKeys.iterator();
while (it.hasNext()) {
       String data = it.next();
       keysList.add(data);
}

Note: You should have configured redisTemplate with StringRedisSerializer in your bean

If you use java based bean configuration

redisTemplate.setDefaultSerializer(new StringRedisSerializer());

If you use spring.xml based bean configuration

<bean id="stringRedisSerializer" class="org.springframework.data.redis.serializer.StringRedisSerializer"/>

<!-- redis template definition -->
<bean
    id="redisTemplate"
    class="org.springframework.data.redis.core.RedisTemplate"
    p:connection-factory-ref="jedisConnectionFactory"
    p:keySerializer-ref="stringRedisSerializer"
    />

2. From JedisConnectionFactory

RedisConnection redisConnection = template.getConnectionFactory().getConnection();
Set<byte[]> redisKeys = redisConnection.keys("samplekey*".getBytes());
List<String> keysList = new ArrayList<>();
Iterator<byte[]> it = redisKeys.iterator();
while (it.hasNext()) {
       byte[] data = (byte[]) it.next();
       keysList.add(new String(data, 0, data.length));
}
redisConnection.close();

If you don't close this connection explicitly, you will run into an exhaustion of the underlying jedis connection pool as said in https://stackoverflow.com/a/36641934/3884173.

Answer 6

Try redisTemplate.setKeySerializer(new StringRedisSerializer());