![]() To change the number of partitions for a distribute cache service, edit the cache configuration file and add a element, within the element, that includes the number of partitions to use for the service. However, larger clusters require more partitions to ensure optimal performance. The default partition count is typically acceptable for clusters containing up to 16 cache servers. For example, each cache server in a cluster of four cache servers manages 64 partitions. Each cache server in the cluster that hosts a distributed cache service manages a balanced number of the partitions. The default partition count for a distributed cache service is 257 partitions. ![]() Also, note that while the Order is co-located with the child LineItems, Coherence does not currently support composite operations that span multiple caches (for example, updating the Order and the collection of LineItems within a single invocation request .EntryProcessor). Note that association is based on the cache key, not the value (otherwise updating a cache entry could cause it to change partitions). There are two ways to ensure that a set of cache entries are co-located. Note that making the association too general (having too many keys associated with the same "group id") can cause a "lumpy" distribution (if all child keys return the same association key regardless of what the parent key is, the child keys are all assigned to a single partition, and are not spread across the cluster). This fact may help minimize the size impact on the child key classes that do not contain the parent key information (as it is derived data, the size of the data may be decided explicitly, and it also does not affect the behavior of the key). All that matters is that all child keys return the same associated key it does not matter whether the associated key is an actual key (it is simply a "group id"). It could be a single field of the parent key (even if it is non-unique), or an integer hash of the parent key. The association does not have to be directly tied to the actual parent key - it only must be a functional mapping of the parent key. In the Order- LineItem example above, the Order objects would be partitioned normally, and the LineItem objects would be associated with the appropriate Order object. Similarly, the association logic applies to the key class, not the value class.Īffinity is specified in terms of a relationship to a partitioned key. As a result, the association information must be present in the key class. Data affinity is specified in terms of entry keys (not values).
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