org.apache.pig.piggybank.storage

Class FixedWidthStorer

java.lang.Object

org.apache.pig.StoreFunc

org.apache.pig.piggybank.storage.FixedWidthStorer

All Implemented Interfaces:

StoreFuncInterface

public class FixedWidthStorer
extends StoreFunc

Stores Pig records in a fixed-width file format. Takes a string argument specifying the ranges of each column in a unix 'cut'-like format. Ex: '-5, 10-12, 14, 20-' Ranges are comma-separated, 1-indexed (for ease of use with 1-indexed text editors), and inclusive. A single-column field at position n may be specified as either 'n-n' or simply 'n'. A second optional argument specifies whether to write a header record with the names of each field. 'WRITE_HEADER' writes a header record; 'NO_HEADER' and the default does not write one. All datetimes are stored in UTC. Column spec idea and syntax parser borrowed from Russ Lankenau's FixedWidthLoader implementation at https://github.com/rlankenau/fixed-width-pig-loader

Constructor Summary

Constructors

Constructor and Description
FixedWidthStorer()
FixedWidthStorer(String columnSpec)
FixedWidthStorer(String columnSpec, String headerStr)

Method Summary

Modifier and Type	Method and Description
void	checkSchema(ResourceSchema s) Set the schema for data to be stored.
org.apache.hadoop.mapreduce.OutputFormat	getOutputFormat() Return the OutputFormat associated with StoreFunc.
String[]	getPartitionKeys(String location, org.apache.hadoop.mapreduce.Job job)
ResourceStatistics	getStatistics(String location, org.apache.hadoop.mapreduce.Job job)
void	prepareToWrite(org.apache.hadoop.mapreduce.RecordWriter writer) Initialize StoreFunc to write data.
void	putNext(Tuple t) Write a tuple to the data store.
void	setPartitionFilter(Expression partitionFilter)
void	setStoreFuncUDFContextSignature(String signature) This method will be called by Pig both in the front end and back end to pass a unique signature to the StoreFunc which it can use to store information in the UDFContext which it needs to store between various method invocations in the front end and back end.
void	setStoreLocation(String location, org.apache.hadoop.mapreduce.Job job) Communicate to the storer the location where the data needs to be stored.
void	storeStatistics(ResourceStatistics stats, String location, org.apache.hadoop.mapreduce.Job job)

Methods inherited from class org.apache.pig.StoreFunc

cleanupOnFailure, cleanupOnFailureImpl, cleanupOnSuccess, relToAbsPathForStoreLocation, supportsParallelWriteToStoreLocation, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

FixedWidthStorer

public FixedWidthStorer()

FixedWidthStorer

public FixedWidthStorer(String columnSpec)

FixedWidthStorer

public FixedWidthStorer(String columnSpec,
                        String headerStr)

Method Detail

getOutputFormat

public org.apache.hadoop.mapreduce.OutputFormat getOutputFormat()
                                                         throws IOException

Description copied from class: StoreFunc

Return the OutputFormat associated with StoreFunc. This will be called on the front end during planning and on the backend during execution.

Specified by:

getOutputFormat in interface StoreFuncInterface

Specified by:

getOutputFormat in class StoreFunc

Returns:

the OutputFormat associated with StoreFunc

Throws:

IOException - if an exception occurs while constructing the OutputFormat

setStoreLocation

public void setStoreLocation(String location,
                             org.apache.hadoop.mapreduce.Job job)
                      throws IOException

Description copied from class: StoreFunc

Communicate to the storer the location where the data needs to be stored. The location string passed to the StoreFunc here is the return value of StoreFunc.relToAbsPathForStoreLocation(String, Path) This method will be called in the frontend and backend multiple times. Implementations should bear in mind that this method is called multiple times and should ensure there are no inconsistent side effects due to the multiple calls. StoreFunc.checkSchema(ResourceSchema) will be called before any call to StoreFunc.setStoreLocation(String, Job).

Specified by:

setStoreLocation in interface StoreFuncInterface

Specified by:

setStoreLocation in class StoreFunc

Parameters:

location - Location returned by StoreFunc.relToAbsPathForStoreLocation(String, Path)

job - The Job object

Throws:

IOException - if the location is not valid.

setStoreFuncUDFContextSignature

public void setStoreFuncUDFContextSignature(String signature)

Description copied from class: StoreFunc

This method will be called by Pig both in the front end and back end to pass a unique signature to the StoreFunc which it can use to store information in the UDFContext which it needs to store between various method invocations in the front end and back end. This method will be called before other methods in StoreFunc. This is necessary because in a Pig Latin script with multiple stores, the different instances of store functions need to be able to find their (and only their) data in the UDFContext object. The default implementation is a no-op.

Specified by:

setStoreFuncUDFContextSignature in interface StoreFuncInterface

Overrides:

setStoreFuncUDFContextSignature in class StoreFunc

Parameters:

signature - a unique signature to identify this StoreFunc

checkSchema

public void checkSchema(ResourceSchema s)
                 throws IOException

Description copied from class: StoreFunc

Set the schema for data to be stored. This will be called on the front end during planning if the store is associated with a schema. A Store function should implement this function to check that a given schema is acceptable to it. For example, it can check that the correct partition keys are included; a storage function to be written directly to an OutputFormat can make sure the schema will translate in a well defined way. Default implementation is a no-op.

Specified by:

checkSchema in interface StoreFuncInterface

Overrides:

checkSchema in class StoreFunc

Parameters:

s - to be checked

Throws:

IOException - if this schema is not acceptable. It should include a detailed error message indicating what is wrong with the schema.

prepareToWrite

public void prepareToWrite(org.apache.hadoop.mapreduce.RecordWriter writer)
                    throws IOException

Description copied from class: StoreFunc

Initialize StoreFunc to write data. This will be called during execution on the backend before the call to putNext.

Specified by:

prepareToWrite in interface StoreFuncInterface

Specified by:

prepareToWrite in class StoreFunc

Parameters:

writer - RecordWriter to use.

Throws:

IOException - if an exception occurs during initialization

putNext

public void putNext(Tuple t)
             throws IOException

Description copied from class: StoreFunc

Write a tuple to the data store.

Specified by:

putNext in interface StoreFuncInterface

Specified by:

putNext in class StoreFunc

Parameters:

t - the tuple to store.

Throws:

IOException - if an exception occurs during the write

getStatistics

public ResourceStatistics getStatistics(String location,
                                        org.apache.hadoop.mapreduce.Job job)
                                 throws IOException

Throws:

IOException

storeStatistics

public void storeStatistics(ResourceStatistics stats,
                            String location,
                            org.apache.hadoop.mapreduce.Job job)
                     throws IOException

Throws:

IOException

getPartitionKeys

public String[] getPartitionKeys(String location,
                                 org.apache.hadoop.mapreduce.Job job)
                          throws IOException

Throws:

IOException

setPartitionFilter

public void setPartitionFilter(Expression partitionFilter)
                        throws IOException

Throws:

IOException