org.apache.drill.exec.physical.resultSet.impl

Class SingleVectorState

java.lang.Object

org.apache.drill.exec.physical.resultSet.impl.SingleVectorState

All Implemented Interfaces:

VectorState

Direct Known Subclasses:

SingleVectorState.OffsetVectorState, SingleVectorState.SimpleVectorState

public abstract class SingleVectorState
extends Object
implements VectorState

Base class for a single vector. Handles the bulk of work for that vector. Subclasses are specialized for offset vectors or values vectors. (The "single vector" name contrasts with classes that manage compound vectors, such as a data and offsets vector.)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SingleVectorState.FixedWidthVectorState State for a scalar value vector.
static class	SingleVectorState.IsSetVectorState
static class	SingleVectorState.OffsetVectorState Special case for an offset vector.
static class	SingleVectorState.SimpleVectorState
static class	SingleVectorState.VariableWidthVectorState State for a scalar value vector.

Field Summary

Fields

Modifier and Type	Field and Description
protected ValueVector	backupVector
protected ValueVector	mainVector
protected WriterEvents	writer

Constructor Summary

Constructors

Constructor and Description
SingleVectorState(WriterEvents writer, ValueVector mainVector)

Method Summary

Modifier and Type	Method and Description
int	allocate(int cardinality) Allocate a new vector with the number of elements given.
protected abstract int	allocateVector(ValueVector vector, int cardinality)
void	close() Clear the vector(s) associated with this state.
protected abstract void	copyOverflow(int sourceStartIndex, int sourceEndIndex)
void	dump(HierarchicalFormatter format)
void	harvestWithLookAhead() Exchange the data from the backup vector and the main vector, putting the completed buffers back into the main vectors, and stashing the overflow buffers away in the backup vector.
boolean	isProjected() Report whether this column is projected (has materialized vectors), or is unprojected (has no materialized backing.)
protected static TypeProtos.MajorType	parseVectorType(ValueVector vector) The vector mechanism here relies on the vector metadata.
void	rollover(int cardinality) A column within the row batch overflowed.
void	startBatchWithLookAhead() The previous full batch has been sent downstream and the client is now ready to start writing to the next batch.
<T extends ValueVector> T	vector() Underlying vector: the one presented to the consumer of the result set loader.
static SingleVectorState.SimpleVectorState	vectorState(ColumnMetadata schema, WriterEvents writer, ValueVector mainVector)

Methods inherited from class java.lang.Object

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

Field Detail

writer

protected final WriterEvents writer

mainVector

protected final ValueVector mainVector

backupVector

protected ValueVector backupVector

Constructor Detail

SingleVectorState

public SingleVectorState(WriterEvents writer,
                         ValueVector mainVector)

Method Detail

vector

public <T extends ValueVector> T vector()

Description copied from interface: VectorState

Underlying vector: the one presented to the consumer of the result set loader.

Specified by:

vector in interface VectorState

allocate

public int allocate(int cardinality)

Description copied from interface: VectorState

Allocate a new vector with the number of elements given. If the vector is an array, then the cardinality given is the number of arrays.

Specified by:

allocate in interface VectorState

Parameters:

cardinality - number of elements desired in the allocated vector

Returns:

the number of bytes allocated

allocateVector

protected abstract int allocateVector(ValueVector vector,
                                      int cardinality)

rollover

public void rollover(int cardinality)

A column within the row batch overflowed. Prepare to absorb the rest of the in-flight row by rolling values over to a new vector, saving the complete vector for later. This column could have a value for the overflow row, or for some previous row, depending on exactly when and where the overflow occurs.

Specified by:

rollover in interface VectorState

Parameters:

sourceStartIndex - the index of the row that caused the overflow, the values of which should be copied to a new "look-ahead" vector. If the vector is an array, then the overflowIndex is the position of the first element to be moved, and multiple elements may need to move

parseVectorType

protected static TypeProtos.MajorType parseVectorType(ValueVector vector)

The vector mechanism here relies on the vector metadata. However, if the main vector is nullable, it will contain a values vector which is required. But the values vector will carry metadata that declares it to be nullable. While this is clearly a bug, it is a bug that has become a "feature" and cannot be changed. This code works around this feature by parsing out the actual type of the vector.

Parameters:

vector - the vector to clone, the type of which may not match the metadata declared within that vector

Returns:

the actual major type of the vector

copyOverflow

protected abstract void copyOverflow(int sourceStartIndex,
                                     int sourceEndIndex)

harvestWithLookAhead

public void harvestWithLookAhead()

Exchange the data from the backup vector and the main vector, putting the completed buffers back into the main vectors, and stashing the overflow buffers away in the backup vector. Restore the main vector's last write position.

Specified by:

harvestWithLookAhead in interface VectorState

startBatchWithLookAhead

public void startBatchWithLookAhead()

The previous full batch has been sent downstream and the client is now ready to start writing to the next batch. Initialize that new batch with the look-ahead values saved during overflow of the previous batch.

Specified by:

startBatchWithLookAhead in interface VectorState

close

public void close()

Description copied from interface: VectorState

Clear the vector(s) associated with this state.

Specified by:

close in interface VectorState

isProjected

public boolean isProjected()

Description copied from interface: VectorState

Report whether this column is projected (has materialized vectors), or is unprojected (has no materialized backing.)

Specified by:

isProjected in interface VectorState

Returns:

true if the column is projected to the output, false if not

vectorState

public static SingleVectorState.SimpleVectorState vectorState(ColumnMetadata schema,
                                                              WriterEvents writer,
                                                              ValueVector mainVector)

dump

public void dump(HierarchicalFormatter format)

Specified by:

dump in interface VectorState