What is Oracle Coherence?
Oracle Coherence is nothing but concept of clustered data management through Caching. Coherence provides database caching, HTTP session management, grid agent invocation and distributed queries. Coherence supports many topologies for clustered data management. Each of these topologies helps in improving performance, fault-tolerance etc.,
With clustering mechanism, Oracle Coherence ensures there is no single point of failure or single point of bottleneck for the applications. It provides automatic scale out of servers, at any point of time, we can add new servers to the cluster and the data will be evenly re-distributed with the new members. Every data object in the memory has a back-up on another server of the cluster which helps in automatic high availability of the data.
Coherence provides several cache implementations like Local Cache which is Local on-heap caching for non-clustered caching. Replicated Cache for small, read-heavy caches, Distributed Cache for linear scalability for both read and write access. Data is automatically, dynamically and transparently partitioned across nodes. The distribution algorithm minimizes network traffic and avoids service pauses by incrementally shifting data. Near Cache to Provide the performance of local caching with the scalability of distributed caching.
Coherence has several options for data storage like On-heap for fastest option, though it can affect JVM garbage collection times, NIO RAM--No impact on garbage collection, though it does require serialization/ De-Serialization, File-based--Uses a special disk-optimized storage system to optimize speed.
Coherence supports various types of caching like Read-Through, Write-Through, Refresh-Ahead and Write-Behind caching.
With this we come to an end of a short glimpse of Oracle Coherence Introduction.
