org.apache.hive.hcatalog.data.transfer

Class HCatReader

java.lang.Object

org.apache.hive.hcatalog.data.transfer.HCatReader

Direct Known Subclasses:

HCatInputFormatReader

@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class HCatReader
extends Object

This abstract class is internal to HCatalog and abstracts away the notion of underlying system from which reads will be done.

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.hadoop.conf.Configuration	conf
protected ReaderContext	info
protected ReadEntity	re
protected StateProvider	sp

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HCatReader(org.apache.hadoop.conf.Configuration config, StateProvider sp) This constructor will be invoked by DataTransferFactory at slave nodes.
protected	HCatReader(ReadEntity re, Map<String,String> config) This constructor will be invoked by DataTransferFactory at master node.

Method Summary

Methods

Modifier and Type	Method and Description
abstract ReaderContext	prepareRead() This should be called at master node to obtain ReaderContext which then should be serialized and sent to slave nodes.
abstract Iterator<HCatRecord>	read() This should be called at slave nodes to read HCatRecords

Methods inherited from class java.lang.Object

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

Field Detail

re

protected ReadEntity re

conf

protected org.apache.hadoop.conf.Configuration conf

info

protected ReaderContext info

sp

protected StateProvider sp

Constructor Detail

HCatReader

protected HCatReader(ReadEntity re,
          Map<String,String> config)

This constructor will be invoked by DataTransferFactory at master node. Don't use this constructor. Instead, use DataTransferFactory

Parameters:

re -

config -

HCatReader

protected HCatReader(org.apache.hadoop.conf.Configuration config,
          StateProvider sp)

This constructor will be invoked by DataTransferFactory at slave nodes. Don't use this constructor. Instead, use DataTransferFactory

Parameters:

config -

sp -

Method Detail

prepareRead

public abstract ReaderContext prepareRead()
                                   throws HCatException

This should be called at master node to obtain ReaderContext which then should be serialized and sent to slave nodes.

Returns:

ReaderContext

Throws:

HCatException

read

public abstract Iterator<HCatRecord> read()
                                   throws HCatException

This should be called at slave nodes to read HCatRecords

Returns:

Iterator of HCatRecord

Throws:

HCatException