org.apache.drill.exec.store.pojo

Class AbstractPojoRecordReader<T>

java.lang.Object

org.apache.drill.exec.store.AbstractRecordReader

org.apache.drill.exec.store.pojo.AbstractPojoRecordReader<T>

All Implemented Interfaces:

AutoCloseable, Iterable<T>, RecordReader

Direct Known Subclasses:

DynamicPojoRecordReader, PojoRecordReader

public abstract class AbstractPojoRecordReader<T>
extends AbstractRecordReader
implements Iterable<T>

Parent class for all pojo readers. Pojo readers can be based on java class (field list is predefined) or dynamic. Contains general logic for initiating writers and reading values from each row fields.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_RECORDS_PER_BATCH
protected List<T>	records
protected List<PojoWriter>	writers

Fields inherited from class org.apache.drill.exec.store.AbstractRecordReader

DEFAULT_TEXT_COLS_TO_READ

Fields inherited from interface org.apache.drill.exec.store.RecordReader

ALLOCATOR_INITIAL_RESERVATION, ALLOCATOR_MAX_RESERVATION

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractPojoRecordReader(List<T> records)
protected	AbstractPojoRecordReader(List<T> records, int recordsPerBatch)

Method Summary

Modifier and Type	Method and Description
void	allocate(Map<String,ValueVector> vectorMap)
void	close()
protected abstract Object	getFieldValue(T row, int fieldPosition) Retrieves field value to be written based for given row and field position.
protected PojoWriter	initWriter(Class<?> type, String fieldName, OutputMutator output) Creates writer based input class type and then initiates it.
Iterator<T>	iterator()
int	next() Increments this record reader forward, writing via the provided output mutator into the output batch.
void	setup(OperatorContext context, OutputMutator output) Configure the RecordReader with the provided schema and the record batch that should be written to.
protected abstract List<PojoWriter>	setupWriters(OutputMutator output) Setups writers for each field in the row.

Methods inherited from class org.apache.drill.exec.store.AbstractRecordReader

getColumns, getDefaultColumnsToRead, hasNext, isSkipQuery, isStarQuery, setColumns, toString, transformColumns

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

DEFAULT_RECORDS_PER_BATCH

public static final int DEFAULT_RECORDS_PER_BATCH

See Also:

Constant Field Values

records

protected final List<T> records

writers

protected List<PojoWriter> writers

Constructor Detail

AbstractPojoRecordReader

protected AbstractPojoRecordReader(List<T> records)

AbstractPojoRecordReader

protected AbstractPojoRecordReader(List<T> records,
                                   int recordsPerBatch)

Method Detail

setup

public void setup(OperatorContext context,
                  OutputMutator output)
           throws ExecutionSetupException

Description copied from interface: RecordReader

Configure the RecordReader with the provided schema and the record batch that should be written to.

Specified by:

setup in interface RecordReader

Parameters:

context - operator context for the reader

output - The place where output for a particular scan should be written. The record reader is responsible for mutating the set of schema values for that particular record.

Throws:

ExecutionSetupException

next

public int next()

Description copied from interface: RecordReader

Increments this record reader forward, writing via the provided output mutator into the output batch.

Specified by:

next in interface RecordReader

Returns:

The number of additional records added to the output.

allocate

public void allocate(Map<String,ValueVector> vectorMap)
              throws OutOfMemoryException

Specified by:

allocate in interface RecordReader

Overrides:

allocate in class AbstractRecordReader

Throws:

OutOfMemoryException

close

public void close()

Specified by:

close in interface AutoCloseable

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T>

initWriter

protected PojoWriter initWriter(Class<?> type,
                                String fieldName,
                                OutputMutator output)
                         throws ExecutionSetupException

Creates writer based input class type and then initiates it.

Parameters:

type - class type

fieldName - field name

output - output mutator

Returns:

pojo writer

Throws:

ExecutionSetupException

setupWriters

protected abstract List<PojoWriter> setupWriters(OutputMutator output)
                                          throws ExecutionSetupException

Setups writers for each field in the row.

Parameters:

output - output mutator

Returns:

list of pojo writers

Throws:

ExecutionSetupException

getFieldValue

protected abstract Object getFieldValue(T row,
                                        int fieldPosition)

Retrieves field value to be written based for given row and field position.

Parameters:

row - current row

fieldPosition - current field position

Returns:

field value to be written for given row