org.apache.pig.builtin

Class ParquetLoader

java.lang.Object

org.apache.pig.LoadFunc

org.apache.pig.LoadFuncWrapper

org.apache.pig.LoadFuncMetadataWrapper

org.apache.pig.builtin.ParquetLoader

All Implemented Interfaces:

LoadMetadata, LoadPredicatePushdown, LoadPushDown

public class ParquetLoader
extends LoadFuncMetadataWrapper
implements LoadPushDown, LoadPredicatePushdown

Wrapper class which will delegate calls to parquet.pig.ParquetLoader

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.pig.LoadPushDown

LoadPushDown.OperatorSet, LoadPushDown.RequiredField, LoadPushDown.RequiredFieldList, LoadPushDown.RequiredFieldResponse

Constructor Summary

Constructors

Constructor and Description
ParquetLoader()
ParquetLoader(java.lang.String requestedSchemaStr)

Method Summary

Modifier and Type	Method and Description
java.util.List<LoadPushDown.OperatorSet>	getFeatures() Determine the operators that can be pushed to the loader.
java.util.List<java.lang.String>	getPredicateFields(java.lang.String location, org.apache.hadoop.mapreduce.Job job) Find what fields of the data can support predicate pushdown.
java.util.List<Expression.OpType>	getSupportedExpressionTypes() Indicate operations on fields supported by the loader for predicate pushdown
LoadPushDown.RequiredFieldResponse	pushProjection(LoadPushDown.RequiredFieldList requiredFieldList) Indicate to the loader fields that will be needed.
void	setLocation(java.lang.String location, org.apache.hadoop.mapreduce.Job job) Communicate to the loader the location of the object(s) being loaded.
void	setPushdownPredicate(Expression predicate) Push down expression to the loader

Methods inherited from class org.apache.pig.LoadFuncMetadataWrapper

getPartitionKeys, getSchema, getStatistics, setLoadFunc, setPartitionFilter

Methods inherited from class org.apache.pig.LoadFuncWrapper

getInputFormat, getLoadCaster, getMethodName, getNext, loadFunc, prepareToRead, relativeToAbsolutePath, setLoadFunc, setUDFContextSignature

Methods inherited from class org.apache.pig.LoadFunc

addCredentials, getAbsolutePath, getCacheFiles, getGlobPaths, getPathStrings, getShipFiles, join, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

ParquetLoader

public ParquetLoader()
              throws FrontendException

Throws:

FrontendException

ParquetLoader

public ParquetLoader(java.lang.String requestedSchemaStr)
              throws FrontendException

Throws:

FrontendException

Method Detail

setLocation

public void setLocation(java.lang.String location,
                        org.apache.hadoop.mapreduce.Job job)
                 throws java.io.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 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.

Overrides:

setLocation in class LoadFuncWrapper

Parameters:

location - Location as returned by LoadFunc.relativeToAbsolutePath(String, Path)

job - the Job object store or retrieve earlier stored information from the UDFContext

Throws:

java.io.IOException - if the location is not valid.

getFeatures

public java.util.List<LoadPushDown.OperatorSet> getFeatures()

Description copied from interface: LoadPushDown

Determine the operators that can be pushed to the loader. Note that by indicating a loader can accept a certain operator (such as selection) the loader is not promising that it can handle all selections. When it is passed the actual operators to push down it will still have a chance to reject them.

Specified by:

getFeatures in interface LoadPushDown

Returns:

list of all features that the loader can support

pushProjection

public LoadPushDown.RequiredFieldResponse pushProjection(LoadPushDown.RequiredFieldList requiredFieldList)
                                                  throws FrontendException

Description copied from interface: LoadPushDown

Indicate to the loader fields that will be needed. This can be useful for loaders that access data that is stored in a columnar format where indicating columns to be accessed a head of time will save scans. This method will not be invoked by the Pig runtime if all fields are required. So implementations should assume that if this method is not invoked, then all fields from the input are required. If the loader function cannot make use of this information, it is free to ignore it by returning an appropriate Response

Specified by:

pushProjection in interface LoadPushDown

Parameters:

requiredFieldList - RequiredFieldList indicating which columns will be needed. This structure is read only. User cannot make change to it inside pushProjection.

Returns:

Indicates which fields will be returned

Throws:

FrontendException

getPredicateFields

public java.util.List<java.lang.String> getPredicateFields(java.lang.String location,
                                                           org.apache.hadoop.mapreduce.Job job)
                                                    throws java.io.IOException

Description copied from interface: LoadPredicatePushdown

Find what fields of the data can support predicate pushdown.

Specified by:

getPredicateFields in interface LoadPredicatePushdown

Parameters:

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 JobContextImpl.getConfiguration() and not to set/query any runtime job information.

Returns:

list of field names that can be pushed down. Implementations should return null to indicate that there are no fields that support predicate pushdown

Throws:

java.io.IOException - if an exception occurs while retrieving predicate fields

getSupportedExpressionTypes

public java.util.List<Expression.OpType> getSupportedExpressionTypes()

Description copied from interface: LoadPredicatePushdown

Indicate operations on fields supported by the loader for predicate pushdown

Specified by:

getSupportedExpressionTypes in interface LoadPredicatePushdown

Returns:

List of operations supported by the predicate pushdown loader

setPushdownPredicate

public void setPushdownPredicate(Expression predicate)
                          throws java.io.IOException

Description copied from interface: LoadPredicatePushdown

Push down expression to the loader

Specified by:

setPushdownPredicate in interface LoadPredicatePushdown

Parameters:

predicate - expression to be filtered by the loader.

Throws:

java.io.IOException