org.apache.pig.piggybank.evaluation.datetime
Class DiffDate

java.lang.Object
  extended by org.apache.pig.EvalFunc<Integer>
      extended by org.apache.pig.piggybank.evaluation.datetime.DiffDate

public class DiffDate
extends EvalFunc<Integer>

Syntax:
int DiffDate(String yyyymmdd1, String yyyymmdd2).
Input:
date string in "yyyymmdd" format.
Output:
(date1-date2) in days, can be negative.


Field Summary
 
Fields inherited from class org.apache.pig.EvalFunc
log, pigLogger, reporter, returnType
 
Constructor Summary
DiffDate()
           
 
Method Summary
 Integer exec(Tuple input)
          This callback method must be implemented by all subclasses.
 List<FuncSpec> getArgToFuncMapping()
          Allow a UDF to specify type specific implementations of itself.
 Schema outputSchema(Schema input)
          Report the schema of the output of this UDF.
 
Methods inherited from class org.apache.pig.EvalFunc
finish, 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

DiffDate

public DiffDate()
Method Detail

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<Integer>
Parameters:
input - Schema of the input
Returns:
Schema of the output

exec

public Integer exec(Tuple input)
             throws IOException
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<Integer>
Parameters:
input - the Tuple to be processed.
Returns:
result, of type T.
Throws:
IOException

getArgToFuncMapping

public List<FuncSpec> getArgToFuncMapping()
                                   throws FrontendException
Description copied from class: EvalFunc
Allow a UDF to specify type specific implementations of itself. For example, an implementation of arithmetic sum might have int and float implementations, since integer arithmetic performs much better than floating point arithmetic. Pig's typechecker will call this method and using the returned list plus the schema of the function's input data, decide which implementation of the UDF to use.

Overrides:
getArgToFuncMapping in class EvalFunc<Integer>
Returns:
A List containing FuncSpec objects representing the EvalFunc class which can handle the inputs corresponding to the schema in the objects. Each FuncSpec should be constructed with a schema that describes the input for that implementation. For example, the sum function above would return two elements in its list:
  1. FuncSpec(this.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.DOUBLE)))
  2. FuncSpec(IntSum.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.INTEGER)))
This would indicate that the main implementation is used for doubles, and the special implementation IntSum is used for ints.
Throws:
FrontendException


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