org.apache.hawq.pxf.plugins.hbase

Class HBaseAccessor

java.lang.Object

org.apache.hawq.pxf.api.utilities.Plugin

org.apache.hawq.pxf.plugins.hbase.HBaseAccessor

All Implemented Interfaces:

ReadAccessor

public class HBaseAccessor
extends Plugin
implements ReadAccessor

Accessor for HBase. This class is responsible for opening the HBase table requested and for iterating over its relevant fragments (regions) to return the relevant table's rows.

The table is divided into several splits. Each accessor instance is assigned a single split. For each region, a Scan object is used to describe the requested rows.

The class supports filters using the HBaseFilterBuilder. Regions can be filtered out according to input from HBaseFilterBuilder.

Field Summary

Fields inherited from class org.apache.hawq.pxf.api.utilities.Plugin

inputData

Constructor Summary

Constructors

Constructor and Description
HBaseAccessor(InputData input) Constructs HBaseTupleDescription based on HAWQ table description and initializes the scan start and end keys of the HBase table to default values.

Method Summary

Modifier and Type	Method and Description
void	closeForRead() Closes the HBase table.
boolean	openForRead() Opens the HBase table.
OneRow	readNextObject() Returns the next row in the HBase table, null if end of fragment.

Methods inherited from class org.apache.hawq.pxf.api.utilities.Plugin

isThreadSafe

Methods inherited from class java.lang.Object

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

Constructor Detail

HBaseAccessor

public HBaseAccessor(InputData input)

Constructs HBaseTupleDescription based on HAWQ table description and initializes the scan start and end keys of the HBase table to default values.

Parameters:

input - query information, contains HBase table name and filter

Method Detail

openForRead

public boolean openForRead()
                    throws java.lang.Exception

Opens the HBase table.

Specified by:

openForRead in interface ReadAccessor

Returns:

true if the current fragment (split) is available for reading and includes in the filter

Throws:

java.lang.Exception - if opening the resource failed

closeForRead

public void closeForRead()
                  throws java.lang.Exception

Closes the HBase table.

Specified by:

closeForRead in interface ReadAccessor

Throws:

java.lang.Exception - if closing the resource failed

readNextObject

public OneRow readNextObject()
                      throws java.io.IOException

Returns the next row in the HBase table, null if end of fragment.

Specified by:

readNextObject in interface ReadAccessor

Returns:

the object which was read

Throws:

java.io.IOException