Examples of com.cloudera.cdk.data.FieldPartitioner

com.cloudera.cdk.data.FieldPartitioner

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 PartitionStrategy


    PartitionStrategy strategy = expression.evaluate();
    List<FieldPartitioner> fieldPartitioners = strategy.getFieldPartitioners();
    Assert.assertEquals(2, fieldPartitioners.size());


    FieldPartitioner fp0 = fieldPartitioners.get(0);
    Assert.assertEquals(YearFieldPartitioner.class, fp0.getClass());
    Assert.assertEquals("timestamp", fp0.getSourceName());
    Assert.assertEquals("year", fp0.getName());


    FieldPartitioner fp1 = fieldPartitioners.get(1);
    Assert.assertEquals(MinuteFieldPartitioner.class, fp1.getClass());
    Assert.assertEquals("timestamp", fp1.getSourceName());
    Assert.assertEquals("minute", fp1.getName());


    Assert.assertEquals(expr, PartitionExpression.toExpression(strategy));
  }

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Examples of com.cloudera.cdk.data.FieldPartitioner

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