org.apache.pig.backend.hadoop.hbase
Class HBaseStorage

java.lang.Object
  extended by org.apache.pig.LoadFunc
      extended by org.apache.pig.backend.hadoop.hbase.HBaseStorage

public class HBaseStorage
extends LoadFunc

A Hbase Loader


Constructor Summary
HBaseStorage(String columnList)
          Constructor.
 
Method Summary
 org.apache.hadoop.mapreduce.InputFormat getInputFormat()
          This will be called during planning on the front end.
 Tuple getNext()
          Retrieves the next tuple to be processed.
 void prepareToRead(org.apache.hadoop.mapreduce.RecordReader reader, PigSplit split)
          Initializes LoadFunc for reading data.
 String relativeToAbsolutePath(String location, org.apache.hadoop.fs.Path curDir)
          This method is called by the Pig runtime in the front end to convert the input location to an absolute path if the location is relative.
 void setLocation(String location, org.apache.hadoop.mapreduce.Job job)
          Communicate to the loader the location of the object(s) being loaded.
 
Methods inherited from class org.apache.pig.LoadFunc
getAbsolutePath, getLoadCaster, getPathStrings, join, setUDFContextSignature
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

HBaseStorage

public HBaseStorage(String columnList)
Constructor. Construct a HBase Table loader to load the cells of the provided columns.

Parameters:
columnList - columnlist that is a presented string delimited by space.
Method Detail

getNext

public Tuple getNext()
              throws IOException
Description copied from class: LoadFunc
Retrieves the next tuple to be processed. Implementations should NOT reuse tuple objects (or inner member objects) they return across calls and should return a different tuple object in each call.

Specified by:
getNext in class LoadFunc
Returns:
the next tuple to be processed or null if there are no more tuples to be processed.
Throws:
IOException - if there is an exception while retrieving the next tuple

getInputFormat

public org.apache.hadoop.mapreduce.InputFormat getInputFormat()
Description copied from class: LoadFunc
This will be called during planning on the front end. This is the instance of InputFormat (rather than the class name) because the load function may need to instantiate the InputFormat in order to control how it is constructed.

Specified by:
getInputFormat in class LoadFunc
Returns:
the InputFormat associated with this loader.

prepareToRead

public void prepareToRead(org.apache.hadoop.mapreduce.RecordReader reader,
                          PigSplit split)
Description copied from class: LoadFunc
Initializes LoadFunc for reading data. This will be called during execution before any calls to getNext. The RecordReader needs to be passed here because it has been instantiated for a particular InputSplit.

Specified by:
prepareToRead in class LoadFunc
Parameters:
reader - RecordReader to be used by this instance of the LoadFunc
split - The input PigSplit to process

setLocation

public void setLocation(String location,
                        org.apache.hadoop.mapreduce.Job job)
                 throws IOException
Description copied from class: LoadFunc
Communicate to the loader the location of the object(s) being loaded. The location string passed to the LoadFunc here is the return value of LoadFunc.relativeToAbsolutePath(String, Path). Implementations should use this method to communicate the location (and any other information) to its underlying InputFormat through the Job object. This method will be called in the 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.

Specified by:
setLocation in class LoadFunc
Parameters:
location - Location as returned by LoadFunc.relativeToAbsolutePath(String, Path)
job - the Job object store or retrieve earlier stored information from the UDFContext
Throws:
IOException - if the location is not valid.

relativeToAbsolutePath

public String relativeToAbsolutePath(String location,
                                     org.apache.hadoop.fs.Path curDir)
                              throws IOException
Description copied from class: LoadFunc
This method is called by the Pig runtime in the front end to convert the input location to an absolute path if the location is relative. The loadFunc 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)

Overrides:
relativeToAbsolutePath in class LoadFunc
Parameters:
location - location as provided in the "load" statement of the script
curDir - the current working direction based on any "cd" statements in the script before the "load" 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


Copyright © ${year} The Apache Software Foundation