org.apache.drill.exec.store

Interface RecordReader

All Superinterfaces:

AutoCloseable

All Known Implementing Classes:

AbstractPojoRecordReader, AbstractRecordReader, CommonParquetRecordReader, DrillParquetReader, DruidRecordReader, DynamicPojoRecordReader, FindLimit0Visitor.RelDataTypeReader, HBaseRecordReader, HiveDefaultRecordReader, HiveTextRecordReader, JSONRecordReader, KuduRecordReader, LTSVRecordReader, MaprDBJsonRecordReader, MockRecordReader, MongoRecordReader, OpenTSDBRecordReader, ParquetRecordReader, PojoRecordReader, RestrictedJsonRecordReader

public interface RecordReader
extends AutoCloseable

Field Summary

Fields

Modifier and Type	Field and Description
static long	ALLOCATOR_INITIAL_RESERVATION
static long	ALLOCATOR_MAX_RESERVATION

Method Summary

Modifier and Type	Method and Description
void	allocate(Map<String,ValueVector> vectorMap)
boolean	hasNext() Check if the reader may have potentially more data to be read in subsequent iterations.
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.

Methods inherited from interface java.lang.AutoCloseable

close

Field Detail

ALLOCATOR_INITIAL_RESERVATION

static final long ALLOCATOR_INITIAL_RESERVATION

See Also:

Constant Field Values

ALLOCATOR_MAX_RESERVATION

static final long ALLOCATOR_MAX_RESERVATION

See Also:

Constant Field Values

Method Detail

setup

void setup(OperatorContext context,
           OutputMutator output)
    throws ExecutionSetupException

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

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

allocate

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

Throws:

OutOfMemoryException

hasNext

boolean hasNext()

Check if the reader may have potentially more data to be read in subsequent iterations. Certain types of readers such as repeatable readers can be invoked multiple times, so this method will allow ScanBatch to check with the reader before closing it.

Returns:

return true if there could potentially be more reads, false otherwise

next

int next()

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

Returns:

The number of additional records added to the output.