I would like to know if it's possible to configure two different Redis database with different persistence options at the same time:
eg:
redis db 0 => appendonly=no
redis db 1 => appendonly=yes
NO, you CANNOT do that. Instead, you should launch two Redis instances, and config each instance with different persistence option.
Related
I have 3 redis instance with redis. One is the master and the other two, are the slaves. I have connected to master node and get info by redis-cli with INFO command. I can see the parameter cluster_enabled:0 and
#Replication
role:master
connected_slaves:2
slave0:ip=xxxxx,port=6379,state=online,offset=15924636776,lag=1
slave1:ip=xxxxx,port=6379,state=online,offset=15924636776,lag=0
And the keyspace, each node has different dbs. I need to migrate all data to a single memorystore in GCP but I don't know how. Anyone can help me?
Since the two nodes are slaves and clustering is not enabled, you only need to replicate the master node. RIOT is a great tool for migrating data in and out of Redis.
However, if you say DB by node do you mean redis DB that you access by select? In that case you'll need to prefix keys as there may be overlap between the keysets of the DBs.
I think setting up another Redis cluster in a single node configuration is the least of your worries.
The real challenge for you would be migrating all your records over to the new setup. This is not a simple question to answer and would depend heavily on multiple factors:
The total size of your data being migrated
Is this is a live Database in production
Do you want to keep the two DB schemas in your new configuration separate?
Ok, I believe currently your Redis Instances are hosted on Google Compute Engine.
And you are looking to migrate to Memorystore for Redis.
As mentioned here, you can leverage Redis snapshots for this. It provides you step-wise instructions on how to achieve this, leveraging GCS buckets as transient storage.
import data into Cloud Memorystore instances using RDB (Redis Database Backup) snapshots, as well as back up data from existing Redis instances.
I have 3 redis servers running in docker containers. From redis-cli I can SET on specific server.
SET myValue 100
How can I do this with StackExchange.Redis client?
I don't see anything in server api that allows to do that. Bear in mind that I don't know much about Redis at all.
var connection = ConnectionMultiplexer.Connect("localhost:6379,localhost:6380,localhost:6381");
var server = connection.GetServer("localhost", 6381);
server.???
SE.Redis expects to be managing a single logical keyspace; the support for multiple nodes is intended either for master/replica setups, or for redis-cluster (although, in the case of cluster, node discovery is achieved via the redis API, so a single node would be fine if it is reachable). With that in place: the selection of servers is implicit from the operation (i.e. writes need to go to a master, and in the case of "cluster", the keyspace shard mapping should be applied).
If you want to write to separate servers as though they are separate databases, you should use a connection per server; not a single connection that spans them all. Right now, SE.Redis is probably detecting 3 master nodes and electing to use one of them arbitrarily. You can see what it thinks by passing a TextWriter to the Connect/ConnectAsync method.
We are using redis. We have two set of data. One set of data(Assume it is using the prefix redis:local: eg: redis:local:key1) is used by the main application and no need of replication.
Another set of data (Prefix redis:replicate: eg: redis:replicate:key2) is used by the main application and should be replicated to slave redis instances.
I have two questions.
Is it possible to configure redis to replicate only keys with prefix redis:replicate:?
If that is not possible, Is it possible to configure redis to replicate only one database? We will store the first set of data in database-0 and the second set of data in database-1. So we have to replicate only database-1.
Currenly, we are running two instances of redis to solve the issue.
Redis only supports replication of whole instances. Limiting replication to a key prefix or database is not possible.
Running two instances of Redis is simplest and reliable option.
Another way would be to write a custom replication program which is difficult and failure prone in comparison.
There is also another question concerning replication of only one database: Replicate a single Redis database from an instance that has multiple databases
Most folks seem to recommend running separate Redis instances on different ports (6379 and 6380). Why is this more commonly recommended over creating a second database? I'm not completely through the documentation yet, but most examples don't really mention 'selection of a Redis database' when connecting. An example from the Ruby client, nrk/predis's README:
$redis = new Predis\Client(array(
'scheme' => 'tcp',
'host' => '10.0.0.1',
'port' => 6379,
));
We currently run Hubot in our office with Campfire, and I'm working on a second one for GTalk since you can only have a single adapter in use for each Hubot instance. So I'm considering creating a second database or instance of Redis so that data between the two hubots is isolated. But before I got much further, I wanted to understand why you would use separate instances instead of just creating a second database.
Two main reasons:
using multiple databases is considered generally bad and to be deprecated some day, and they have some performance penalties, though pretty minor.
the main reason is that redis is single threaded, if you need two different data sources, another redis instance will improve performance since it will utilize another CPU you probably have, whereas one instance will always utilize just one.
Also different redis instances can have distinct persistence settings. For example one instance can use only memory and other can use files as storage
Redis Persistence
Then there are other advantages as having separate auth passwords, LRU strategies, etc - which can only be done at the instance level.
For instance... From the same rails app I would like to be able to queue email to one redis db at "localhost:6379" and imports to another redis db at "10.0.0.5:6379".
This seems to set the redis connection app wide.
Resque.redis = "localhost:6379"
Is there a way to instantiate and use multiple redis connections with Resque?
This project does what im looking for!
https://github.com/redsquirrel/resque_redis_composite