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org.apache.crunch
Interface Target

All Known Subinterfaces:

MapReduceTarget, PathTarget, ReadableSourceTarget<T>, SourceTarget<T>, TableSourceTarget<K,V>

public interface Target

A Target represents the output destination of a Crunch PCollection in the context of a Crunch job.

Nested Class Summary

static class

Target.WriteMode An enum to represent different options the client may specify for handling the case where the output path, table, etc.

Method Summary

boolean	accept(OutputHandler handler, PType<?> ptype) Checks to see if this Target instance is compatible with the given PType.
<T> SourceTarget<T>	asSourceTarget(PType<T> ptype) Attempt to create the SourceTarget type that corresponds to this Target for the given PType, if possible.
Converter<?,?,?,?>	getConverter(PType<?> ptype) Returns the Converter to use for mapping from the output PCollection into the output values expected by this instance.
boolean	handleExisting(Target.WriteMode writeMode, long lastModifiedAt, org.apache.hadoop.conf.Configuration conf) Apply the given WriteMode to this Target instance.

Method Detail

handleExisting

boolean handleExisting(Target.WriteMode writeMode,
                       long lastModifiedAt,
                       org.apache.hadoop.conf.Configuration conf)

Apply the given WriteMode to this Target instance.

Parameters:

writeMode - The strategy for handling existing outputs

conf - The ever-useful Configuration instance

Returns:

true if the target did exist

accept

boolean accept(OutputHandler handler,
               PType<?> ptype)

Checks to see if this Target instance is compatible with the given PType.

Parameters:

handler - The OutputHandler that is managing the output for the job

ptype - The PType to check

Returns:

True if this Target can write data in the form of the given PType, false otherwise

getConverter

Converter<?,?,?,?> getConverter(PType<?> ptype)

Returns the Converter to use for mapping from the output PCollection into the output values expected by this instance.

Parameters:

ptype - The PType of the data that is being written to this instance

Returns:

A valid Converter for the output represented by this instance

asSourceTarget

<T> SourceTarget<T> asSourceTarget(PType<T> ptype)

Attempt to create the SourceTarget type that corresponds to this Target for the given PType, if possible. If it is not possible, return null.

Parameters:

ptype - The PType to use in constructing the SourceTarget

Returns:

A new SourceTarget or null if such a SourceTarget does not exist