org.apache.pig.impl.builtin
Class IdentityColumn

java.lang.Object
  org.apache.pig.EvalFunc<Object>
      org.apache.pig.impl.builtin.IdentityColumn

public class IdentityColumn
extends EvalFunc<Object>

Returns the input, used by DuplicateForEachColumnRewrite to rewrite duplicate columns in ForEach. Not intended for external use

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

IdentityColumn()

Method Summary

Object	exec(Tuple input) This callback method must be implemented by all subclasses.
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, isAsynchronous, progress, setPigLogger, setReporter, warn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IdentityColumn

public IdentityColumn()

Method Detail

exec

public Object exec(Tuple input)
            throws ExecException

Description copied from class: EvalFunc

This callback method must be implemented by all subclasses. This is the method that will be invoked on every Tuple of a given dataset. Since the dataset may be divided up in a variety of ways the programmer should not make assumptions about state that is maintained between invocations of this method.

Specified by:

exec in class EvalFunc<Object>

Parameters:

input - the Tuple to be processed.

Returns:

result, of type T.

Throws:

ExecException

outputSchema

public Schema outputSchema(Schema input)

Description copied from class: EvalFunc

Report the schema of the output of this UDF. Pig will make use of this in error checking, optimization, and planning. The schema of input data to this UDF is provided.

Overrides:

outputSchema in class EvalFunc<Object>

Parameters:

input - Schema of the input

Returns:

Schema of the output