Partitions values for a named field.
Used by a {@link PartitionStrategy} to calculate which partition an entitybelongs in, based on the value of a given field, called the source field. A field partitioner can, in some cases, provide meaningful cardinality hints to query systems. A good example of this is a hash partitioner which always knows the number of buckets produced by the function.
Implementations of {@link FieldPartitioner} are immutable.
@param < S> The type of the source field in the entity. The partition function mustaccept values of this type. @param < T> The type of the target field, which is the type of the return value of thepartition function. @see PartitionStrategyPartitions values for a named field.
Used by a {@link org.kitesdk.data.PartitionStrategy} to calculate which partition an entitybelongs in, based on the value of a given field, called the source field. A field partitioner can, in some cases, provide meaningful cardinality hints to query systems. A good example of this is a hash partitioner which always knows the number of buckets produced by the function.
Implementations of {@link FieldPartitioner} are immutable.
@param < S> The type of the source field in the entity. The partition function mustaccept values of this type. @param < T> The type of the target field, which is the type of the return value of thepartition function. @see org.kitesdk.data.PartitionStrategy
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