org.apache.hadoop.zebra.pig
Class TableStorer

java.lang.Object
  org.apache.pig.StoreFunc
      org.apache.hadoop.zebra.pig.TableStorer

All Implemented Interfaces:

StoreFuncInterface, StoreMetadata

public class TableStorer
extends StoreFunc
implements StoreMetadata

Pig LoadFunc implementation for Zebra Table

Constructor Summary

TableStorer()

TableStorer(String storageHintString)

TableStorer(String storageHintString, String partitionClassString)

TableStorer(String storageHintString, String partitionClassString, String partitionClassArgumentsString)

Method Summary

void	checkSchema(ResourceSchema schema) Set the schema for data to be stored.
org.apache.hadoop.mapreduce.OutputFormat	getOutputFormat() Return the OutputFormat associated with StoreFunc.
void	prepareToWrite(org.apache.hadoop.mapreduce.RecordWriter writer) Initialize StoreFunc to write data.
void	putNext(Tuple tuple) Write a tuple to the data store.
String	relToAbsPathForStoreLocation(String location, org.apache.hadoop.fs.Path curDir) This method is called by the Pig runtime in the front end to convert the output location to an absolute path if the location is relative.
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	storeSchema(ResourceSchema schema, String location, org.apache.hadoop.mapreduce.Job job) Store schema of the data being written
void	storeStatistics(ResourceStatistics stats, String location, org.apache.hadoop.mapreduce.Job job) Store statistics about the data being written.

Methods inherited from class org.apache.pig.StoreFunc

cleanupOnFailure, cleanupOnFailureImpl

Methods inherited from class java.lang.Object

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

Constructor Detail

TableStorer

public TableStorer()

TableStorer

public TableStorer(String storageHintString)

TableStorer

public TableStorer(String storageHintString,
                   String partitionClassString)

TableStorer

public TableStorer(String storageHintString,
                   String partitionClassString,
                   String partitionClassArgumentsString)

Method Detail

putNext

public void putNext(Tuple tuple)
             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:

tuple - the tuple to store.

Throws:

IOException - if an exception occurs during the write

checkSchema

public void checkSchema(ResourceSchema schema)
                 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:

schema - 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.

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

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

relToAbsPathForStoreLocation

public String relToAbsPathForStoreLocation(String location,
                                           org.apache.hadoop.fs.Path curDir)
                                    throws IOException

Description copied from class: StoreFunc

This method is called by the Pig runtime in the front end to convert the output location to an absolute path if the location is relative. The StoreFunc implementation is free to choose how it converts a relative location to an absolute location since this may depend on what the location string represent (hdfs path or some other data source).

Specified by:

relToAbsPathForStoreLocation in interface StoreFuncInterface

Overrides:

relToAbsPathForStoreLocation in class StoreFunc

Parameters:

location - location as provided in the "store" statement of the script

curDir - the current working direction based on any "cd" statements in the script before the "store" statement. If there are no "cd" statements in the script, this would be the home directory -

/user/ 

Returns:

the absolute location based on the arguments passed

Throws:

IOException - if the conversion is not possible

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.

storeSchema

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

Description copied from interface: StoreMetadata

Store schema of the data being written

Specified by:

storeSchema in interface StoreMetadata

Parameters:

schema - Schema to be recorded

location - Location as returned by LoadFunc.relativeToAbsolutePath(String, org.apache.hadoop.fs.Path)

job - The Job object - this should be used only to obtain cluster properties through JobContext.getConfiguration() and not to set/query any runtime job information.

Throws:

IOException

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

storeStatistics

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

Description copied from interface: StoreMetadata

Store statistics about the data being written.

Specified by:

storeStatistics in interface StoreMetadata

Parameters:

stats - statistics to be recorded

location - Location as returned by LoadFunc.relativeToAbsolutePath(String, org.apache.hadoop.fs.Path)

job - The Job object - this should be used only to obtain cluster properties through JobContext.getConfiguration() and not to set/query any runtime job information.

Throws:

IOException