org.apache.pig.builtin
Class SUBTRACT

java.lang.Object
  org.apache.pig.EvalFunc<DataBag>
      org.apache.pig.builtin.SUBTRACT

public class SUBTRACT
extends EvalFunc<DataBag>

SUBTRACT takes two bags as arguments and returns a new bag composed of tuples of first bag not in the second bag.
If null, bag arguments are replaced by empty bags.

The implementation assumes that both bags being passed to this function will fit entirely into memory simultaneously.
If that is not the case the UDF will still function, but it will be very slow.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

SUBTRACT()

Method Summary

DataBag

exec(Tuple input) Compares the two bag fields from input Tuple and returns a new bag composed of elements of first bag not in the second bag.

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, isAsynchronous, outputSchema, progress, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

SUBTRACT

public SUBTRACT()

Method Detail

exec

public DataBag exec(Tuple input)
             throws IOException

Compares the two bag fields from input Tuple and returns a new bag composed of elements of first bag not in the second bag.

Specified by:

exec in class EvalFunc<DataBag>

Parameters:

input - a tuple with exactly two bag fields.

Returns:

result, of type T.

Throws:

IOException - if there are not exactly two fields in a tuple or if they are not DataBag.