KeyDB remains fully compatible with Redis modules API and protocol. As such a migration from Redis to KeyDB is very simple and would be similar to what you would expect migrating in a Redis to Redis scenario.
KeyDB is compatible with all Redis clients as listed here so this should not be a concern. Simply use your client as you would with Redis.
This document will discuss migration from Redis to KeyDB or KeyDB Enterprise and vice versa. In each scenario the methodology is similar. We will look at both an offline migration and a live migration for each scenario.
Using SAVE or BGSAVE you can create an RDB backup file of the database. If you are saving in production where you don't want any downtime it is recommended to use BGSAVE to prevent blocking clients as SAVE performs synchronously.
The dump.rdb file is saved in your redis/keydb working directory.
If you were using Redis, you can now launch KeyDB Open Source or KeyDB Enterprise and point to the .rdb file you created (specified 'dir' in .conf). You can also reuse your previous redis.conf file and append any new config options you wish to use from keydb.conf.
If you are migrating on the same machine with the same .conf file you may want to use the SHUTDOWN command as you will need to shutdown your old node if using identical configuration/same port.
This method may result in brief downtime depending on how you swap over and if you are using the same machine or a different server. If you require zero downtime or data-loss during your swapover, you can use a replica to do a live swapover.
On a live system, if you want a seamless swapover you can simply create a replica node of the server you wish to migrate, then promote the replica to master. See replicaof command reference, or further explanation of replicas here
After the replica is synced you can promote it to master with the REPLICAOF NO ONE command via keydb-cli or redis-cli. This is the simple version, for more details on creating and promoting replica nodes see this document on replication.
The methodology above is the exact same when migrating a single node from KeyDB to KeyDB Enterprise, or from Redis to KeyDB Enterprise.
If you are introducing a KeyDB Enterprise node into a Redis or KeyDB cluster you can create replicas and promote them to master nodes, but this will not necessarily work the other way around with failover. It is not recommended to operate a mix of KeyDB Enterprise, KeyDB Open Source, or Redis nodes together in a cluster other than to do an initial migration.
The process is the same above, however if you have enabled any configuration parameters specific to KeyDB or KeyDB Enterprise, you should disable them prior to migrating back to Redis as the configuration parameters will not be recognized. If you have used commands such as EXPIREMEMBER that is exclusive to KeyDB you may want to remove these prior to migration.
Also keep in mind you may require a larger machine(s) or cluster when migrating back to Redis due to potential performance drops. It is recommended to do some benchmarking to make sure the new instance can handle the load as Redis is single threaded and you may be using 2-16 threads with KeyDB.
If you were using KeyDB Enterprise, Enhanced FLASH may not have been using an rdb file, so ensure there is space to save.