`INFO memory` doesn't work in Redis - redis

I tried INFO memory in redis-cli
but empty result came back.
Am I missing any configuration for this?
Redis version is 2.8.17.

I did the command to the Sentinel instance.
It works fine with the Redis instance.

Related

How to delete all keys from redis cluster

I want to delete all keys from redis cluster by using fast process. I know how to delete the keys by using "redis-cli FLUSHALL". But this command can be slow when the data set is large. I heard that all keys can be cleared from redis cache by re-starting the redis service. I am testing this process on my local mac laptop. I am performing following steps:-
Setting many number of keys on my local redis server by using example command redis-cli SET mykey1 "Hello"
Then Re-starting the redis service "brew services restart redis" in the hope that all keys will be deleted when the service will be back up
Then getting the keys by giving "redis-cli KEYS '*'" command
I still see the keys after step-3
The keys are gone only when I give this command--> redis-cli FLUSHALL? How I can clear the keys by re-starting the redis service locally on my mac laptop first then I will try on QA servers?
You see the keys after restart because there is either RDB or AOF persistence enabled. See https://redis.io/topics/persistence.
RDB is enabled by default. To disable persistence, you need to edit your redis.conf or start as redis-server --save "" --appendonly no
See Is there a way to flushall on a cluster so all keys from master and slaves are deleted from the db on how to use redis-cli to send the command to all cluster nodes.
As dizzyf indicates, use FLUSHALL ASYNC to have the deletion performed in the background. This will create fresh hash maps for each database, while the old ones are deleted (memory reclaimed) progressively by a background thread.
In redis 4.0 and greater, the FLUSHALL ASYNC command was introduced, as a way to delete all the keys in a non-blocking manner. Would this solve your issue?
https://redis.io/commands/flushall
Thank you for links. These were very helpful. I was able to achieve the result by making changes to my redis.conf file with--> redis-server --save "" and --appendonly no. So after these changes, when I now re-start redis service nothing is saved.

Is it safe to run SCRIPT FLUSH on Redis cluster?

Recently, I started to have some trouble with one of me Redis cluster. used_memroy and used_memory_rss increasing constantly.
According to some Googling, I found following discussion:
https://github.com/antirez/redis/issues/4570
Now I am wandering if it is safe to run SCRIPT FLUSH command on my production Redis cluster?
Yes - you can run the SCRIPT FLUSH command safely in a production cluster. The only potential side effect is blocking the server while it executes. Note, however, that you'll want to call it in each of your nodes.

Run redis-cli when redis is running like a service

I have a problem with Redis and redis-cli.
I have running Redis like a service in windows, like you can see in the picture
but when I try to run "redis-cli" it doesn't anything, the console is frozen
I need to monitoring all messages with MONITORING command.
Can you help me please!?
Regards.

Redis Cluster Support in Redis 2.8.19

I just started evaluating Redis. I am using Redis 2.8.19 which the most latest stable release. Redis 2.9 is still unstable and Redis 3.0 is just available for developer's preview (not recommended for production). I was tryin to setus a cluster of Redis and when I changed my redis.conf and appended
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
and started my Redis server by
src/redis-server ./redis.conf
it gave me an error as follows
* FATAL CONFIG FILE ERROR *
Reading the configuration file, at line 2
'cluster-enabled yes'
Bad directive or wrong number of arguments
I googled the error and got to know that my version (2.8.19) does not support cluster. I was still unable to fine any such specification in Redis Docs. My question is simple. Does Redis 2.8.19 supports redis cluster configuration? Or I have to upgrade to Redis 2.9 or Redis 3.0. I am evaluating Redis because I need to deploy it in production. Please guide.
Redis Cluster support is only for versions >= 3.0.0. Redis 3.0.0 will be released as a stable version in a matter of days, it's a good idea to use it if you want to use Cluster. The cluster support is considered to be stable, however for it to be considered mature we want to see adoption. Btw there is already at least a very large site using it in production. Currently the most sane thing to do if you need Redis Cluster is to test it for your use case, and if it looks great, use it.
Redis cluster is supported only in Redis 3.0+ (which is now stable). I have written a simple API called "Simple Redis Cluster Client" which can be used in redis's sub 3.0 versions for running in a cluster like mode (Not precisely a cluster, it just distributes keys among redis nodes based on the key's hashcode, You can have a look # https://github.com/prash-mi/simple-redis-cluster-client
Cluster support for Redis is only from v3 - v2.8.19 doesn't do clustering.

Redis data replication

I am trying to do data replication using redis server and jedis client. What I am asking may be completely wrong. I just started exploring the things today.
I have configured 2 laptops in my network.
Config on node1 is default the config.
Config on node2:
updated redis.conf file to have this line:
slaveof <node1 ip> <port on which redis server is running>
I have a stand-alone java program on both of the nodes.
Case 1:
I did jedis.set("key1", "value1"); from node1 (master). I am able to retrieve key-value from node2.
Case 2:
I did jedis.set("key2", "value2"); from node2 (slave). But I'm not able to see that replicated on the master node.
Question is, is it expected behavior? My requirement is to keep the data in sync on all the nodes.
Thanks.
That is the expected behavior. Writes to the master will propagate to the slave(s), writes to the slave(s) will not propagate to the master. If you want to use Redis, you will have to write to the master and read from the slave(s). See Redis replication documentation.