Package org.apache.drill.exec.store

Class AbstractRecordReader

java.lang.Object

org.apache.drill.exec.store.AbstractRecordReader

All Implemented Interfaces:

AutoCloseable, RecordReader

Direct Known Subclasses:

AbstractPojoRecordReader, CommonParquetRecordReader, DruidRecordReader, FindLimit0Visitor.RelDataTypeReader, HBaseRecordReader, HiveDefaultRecordReader, JSONRecordReader, KuduRecordReader, MockRecordReader, MongoRecordReader, OpenTSDBRecordReader

public abstract class AbstractRecordReader
extends Object
implements RecordReader

Field Summary

Fields

Modifier and Type	Field	Description
protected static final List<SchemaPath>	DEFAULT_TEXT_COLS_TO_READ

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

ALLOCATOR_INITIAL_RESERVATION, ALLOCATOR_MAX_RESERVATION

Constructor Summary

Constructors

Constructor	Description
AbstractRecordReader()

Method Summary

Modifier and Type	Method	Description
void	allocate(Map<String,ValueVector> vectorMap)
protected Collection<SchemaPath>	getColumns()
protected List<SchemaPath>	getDefaultColumnsToRead()
boolean	hasNext()	Check if the reader may have potentially more data to be read in subsequent iterations.
protected boolean	isSkipQuery()	Returns true if reader should skip all of the columns, reporting number of records only.
protected boolean	isStarQuery()
protected final void	setColumns(Collection<SchemaPath> projected)
String	toString()
protected Collection<SchemaPath>	transformColumns(Collection<SchemaPath> projected)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.AutoCloseable

close

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

next, setup

Field Details

DEFAULT_TEXT_COLS_TO_READ

protected static final List<SchemaPath> DEFAULT_TEXT_COLS_TO_READ

Constructor Details

AbstractRecordReader

public AbstractRecordReader()

Method Details

toString

public String toString()

Overrides:

toString in class Object

setColumns

protected final void setColumns(Collection<SchemaPath> projected)

Parameters:

projected - : The column list to be returned from this RecordReader. 1) empty column list: this is for skipAll query. It's up to each storage-plugin to choose different policy of handling skipAll query. By default, it will use * column. 2) NULL : is NOT allowed. It requires the planner's rule, or GroupScan or ScanBatchCreator to handle NULL.

getColumns

protected Collection<SchemaPath> getColumns()

transformColumns

protected Collection<SchemaPath> transformColumns(Collection<SchemaPath> projected)

isStarQuery

protected boolean isStarQuery()

isSkipQuery

protected boolean isSkipQuery()

Returns true if reader should skip all of the columns, reporting number of records only. Handling of a skip query is storage plugin-specific.

allocate

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

Specified by:

allocate in interface RecordReader

Throws:

OutOfMemoryException

hasNext

public boolean hasNext()

Description copied from interface: RecordReader

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.

Specified by:

hasNext in interface RecordReader

Returns:

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

getDefaultColumnsToRead

protected List<SchemaPath> getDefaultColumnsToRead()