datafu.pig.util
Class Coalesce

java.lang.Object
  org.apache.pig.EvalFunc<T>
      datafu.pig.util.ContextualEvalFunc<T>
          datafu.pig.util.AliasableEvalFunc<java.lang.Object>
              datafu.pig.util.Coalesce

public class Coalesce
extends AliasableEvalFunc<java.lang.Object>

Returns the first non-null value from a tuple, just like COALESCE in SQL.

Example:

 define COALESCE datafu.pig.util.COALESCE();

 -- input: 1,2,3,NULL,4,NULL,5
 input = LOAD 'input' AS (val:int);

 -- produces: 1,2,3,99,4,99,5
 coalesced = FOREACH input GENERATE COALESCE(val,99);

 
 

Author:

"Matthew Hayes "

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Coalesce()

Coalesce(java.lang.String option)

Method Summary

java.lang.Object	exec(org.apache.pig.data.Tuple input)
org.apache.pig.impl.logicalLayer.schema.Schema	getOutputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) Specify the output schema as in {link EvalFunc#outputSchema(Schema)}.

Methods inherited from class datafu.pig.util.AliasableEvalFunc

getBag, getBoolean, getDouble, getDouble, getFieldAliases, getFloat, getFloat, getInteger, getInteger, getLong, getLong, getObject, getPosition, getPosition, getPrefixedAliasName, getString, getString, outputSchema

Methods inherited from class datafu.pig.util.ContextualEvalFunc

getContextProperties, getInstanceName, getInstanceProperties, setUDFContextSignature

Methods inherited from class org.apache.pig.EvalFunc

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

Methods inherited from class java.lang.Object

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

Constructor Detail

Coalesce

public Coalesce()

Coalesce

public Coalesce(java.lang.String option)

Method Detail

exec

public java.lang.Object exec(org.apache.pig.data.Tuple input)
                      throws java.io.IOException

Specified by:

exec in class org.apache.pig.EvalFunc<java.lang.Object>

Throws:

java.io.IOException

getOutputSchema

public org.apache.pig.impl.logicalLayer.schema.Schema getOutputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Description copied from class: AliasableEvalFunc

Specify the output schema as in {link EvalFunc#outputSchema(Schema)}.

Specified by:

getOutputSchema in class AliasableEvalFunc<java.lang.Object>

Returns:

outputSchema