Copying all keys in Redis database using MIGRATE - redis

Question

Is it possible to copy all keys from one Redis instance to another remote instance using MIGRATE? I've tried COPY, REPLACE and KEYS without any luck. Each time I get a NOKEY response. If I use any of the MIGRATE commands with a single key it works.
Examples:
MIGRATE my.redis 6379 "*" 0 5000 REPLACE // NOKEY
MIGRATE my.redis 6379 "*" 0 5000 COPY // NOKEY
MIGRATE my.redis 6379 "" 0 5000 KEYS * // NOKEY
MIGRATE my.redis 6379 "" 0 5000 KEYS test // OK

Answer 1

This is an improvement on the answer provided by #ezain since I am unable to post comments. The command uses the correct redis syntax for processing batches of keys, but the arguments to xargs result in the command being called once for every key instead of just once with all the keys included (which means it'll take much more time to complete than is necessary). The following will be much faster in all cases:
redis-cli --raw KEYS '*' | xargs redis-cli MIGRATE my.redis 6379 "" 0 5000 KEYS
If the destination is password protected:
redis-cli --raw KEYS '*' | xargs redis-cli MIGRATE my.redis 6379 "" 0 5000 AUTH password-here KEYS

Answer 2

try run in your shell
redis-cli keys '*' | xargs -I '{}' redis-cli migrate my.redis 6379 "" 0 5000 KEYS '{}'

Answer 3

For a big DBs with a lot of keys it's better to use --scan instead of keys, to avoid Redis lock on KEYS command:
redis-cli --scan | xargs redis-cli MIGRATE my.redis 6379 "" 0 5000 KEYS
Not really related to the question, but in case someone will need it: Redis does not support MIGRATE with a password before 3.0. After 3.0, you can add AUTH parameter to check the permission:
MIGRATE 192.168.0.33 6379 "" 0 5000 AUTH mypassword KEYS user:{info}:age

Answer 4

If you are running on non-managed¹ redis instances, the most ideal way would probably to run the target instance as a replica temporarly and then disable (after all data is copied) the replication.
see the REPLICAOF command in redis. how to apply it (all commands on the target instance):
initiate the replication: $ replicaof source_hostname_or_ip source_port
after everything is done: $ replicaof no one
If you can't use this command¹ then you can try this script on the digital ocean blog: https://www.digitalocean.com/community/tutorials/how-to-migrate-redis-data-to-a-digitalocean-managed-database#step-3-%E2%80%94-building-the-migration-script
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¹ - managed services often restrict the usage of this command see here or here.

Answer 5

I'm not advocating using this, but I tried all of these examples, and many others and did not work. I ended up doing it myself in PHP, so maybe this will help someone else who is stuck.
<?php
$redisSource = new Redis();
$redisSource->connect('1.2.3.4', 6379);
$redisSource->auth('password');
$redisTarget = new Redis();
$redisTarget->connect('127.0.0.1', 6379);
foreach($redisSource->keys('*') as $key) {
$redisTarget->set($key, $redisSource->get($key));
}