org.apache.pig.piggybank.storage
Class FixedWidthStorer

java.lang.Object
  extended by org.apache.pig.StoreFunc
      extended by 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
FixedWidthStorer()
           
FixedWidthStorer(String columnSpec)
           
FixedWidthStorer(String columnSpec, String headerStr)
           
 
Method Summary
 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, 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


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