This section contains all you need to know to maintain Redis Enterprise Software (RS) databases.

    Causal Consistency in an Active-Active Database

    When you enable Causal Consistency in Active-Active databases, the order of operations on a specific key are maintained across all Active-Active database instances. For instance, if operations A and B were applied on the same key and the effect of A was observed by the instance that initiated B before B was applied to the key, then all instances of an Active-Active databases would observe the effect of A before observing the effect of B.

    Database Memory Limits

    When you set a database’s memory limit, you define the maximum size the database can reach in the cluster, across all database replicas and shards, including: Slave shards (if database replication is enabled) Database shards (if database clustering is enabled) If the total size of the database in the cluster reaches the memory limit, the data eviction policy that was defined for the database is applied. The following examples show how different database configurations affect the total database size.

    Delete a Database

    To delete a database in Redis Enterprise Software: Click the relevant database row in the Databases page. The selected database page appears. Select the Configuration tab. Click Delete at the bottom of the page. Confirm the deletion. Deleting an Active-Active database When you delete an Active-Active database (formerly known as CRDB), all instance of the Active-Active database are deleted from all participating clusters. Warning - This action is an immediate, non-reversible, and has no rollback.

    Eviction policies

    The eviction policy defines the methodology that Redis Enterprise Software uses when the database exceeds the memory limit. The eviction policies are: Policy Description  noeviction Returns an error if the memory limit has been reached when trying to insert more data  allkeys-lru Evicts the least recently used keys out of all keys  allkeys-lfu Evicts the least frequently used keys out of all keys  allkeys-random Randomly evicts keys out of all keys  volatile-lru Evicts the least recently used keys out of all keys with an “expire” field set  volatile-lfu Evicts the least frequently used keys out of all keys with an “expire” field set  volatile-random Randomly evicts keys with an “expire” field set  volatile-ttl Evicts the shortest time-to-live keys out of all keys with an “expire” field set.

    High Availability for Slave Shards

    When you enable database replication for your database, Redis Enterprise Software replicates your data to a slave node to make sure that your data is highly available. If the slave node fails or if the master node fails and the slave is promoted to master, the remaining master node is a single point of failure. You can configure high availability for slave shards (slave HA) so that the cluster automatically migrates the slave shards to an available node.

    Updating the Database Configuration

    You can change the configuration of a Redis Enterprise Software (RS) database at any time. To edit the configuration of a database: Go to Database and select the database that you want to edit. Go to Configuration and click Edit at the bottom of the page. The database settings appear. Change the any of the configurable database settings. Note - For Active-Active database instances, most database settings only apply to the instance that you are editing.