接口 org.apache.hadoop.mapred.join.ResetableIterator
的使用

使用ResetableIterator的程序包

程序包	说明
org.apache.hadoop.mapred.join	Given a set of sorted datasets keyed with the same class and yielding equal partitions, it is possible to effect a join of those datasets prior to the map.

org.apache.hadoop.mapred.join中ResetableIterator的使用

实现ResetableIterator的org.apache.hadoop.mapred.join中的类

限定符和类型	类和说明
class	ArrayListBackedIterator<X extends Writable> This class provides an implementation of ResetableIterator.
protected class	JoinRecordReader.JoinDelegationIterator Since the JoinCollector is effecting our operation, we need only provide an iterator proxy wrapping its operation.
protected class	MultiFilterRecordReader.MultiFilterDelegationIterator Proxy the JoinCollector, but include callback to emit.
static class	ResetableIterator.EMPTY<U extends Writable>
class	StreamBackedIterator<X extends Writable> This class provides an implementation of ResetableIterator.

返回ResetableIterator的org.apache.hadoop.mapred.join中的方法

限定符和类型	方法和说明
protected ResetableIterator<V>	MultiFilterRecordReader.getDelegate() Return an iterator returning a single value from the tuple.
protected ResetableIterator<TupleWritable>	JoinRecordReader.getDelegate() Return an iterator wrapping the JoinCollector.
protected abstract ResetableIterator<X>	CompositeRecordReader.getDelegate() Obtain an iterator over the child RRs apropos of the value type ultimately emitted from this join.