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

Class RepeatedVectorState

java.lang.Object

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

All Implemented Interfaces:

VectorState

public class RepeatedVectorState
extends Object
implements VectorState

Vector state for a scalar array (repeated scalar) vector. Manages both the offsets vector and data vector during overflow and other operations.

Constructor Summary

Constructors

Constructor and Description
RepeatedVectorState(ArrayWriter writer, RepeatedValueVector vector)

Method Summary

Modifier and Type	Method and Description
int	allocate(int cardinality) Allocate a new vector with the number of elements given.
void	close() Clear the vector(s) associated with this state.
void	dump(HierarchicalFormatter format)
void	harvestWithLookAhead() A batch is being harvested after an overflow.
boolean	isProjected() Report whether this column is projected (has materialized vectors), or is unprojected (has no materialized backing.)
void	rollover(int newCardinality) The column is a scalar or an array of scalars.
void	startBatchWithLookAhead() A new batch is starting while an look-ahead vector exists.
<T extends ValueVector> T	vector() Underlying vector: the one presented to the consumer of the result set loader.

Methods inherited from class java.lang.Object

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

Constructor Detail

RepeatedVectorState

public RepeatedVectorState(ArrayWriter writer,
                           RepeatedValueVector vector)

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

rollover

public void rollover(int newCardinality)

The column is a scalar or an array of scalars. We need to roll over both the column values and the offsets that point to those values. The index provided is the index into the offset vector. We use that to obtain the index of the values to roll-over.

Data structure:

 RepeatedVectorState (this class)
 +- OffsetVectorState
 .  +- OffsetVectorWriter (A)
 .  +- Offset vector (B)
 .  +- Backup (e.g. look-ahead) offset vector
 +- ValuesVectorState
 .  +- Scalar (element) writer (C)
 .  +- Data (elements) vector (D)
 .  +- Backup elements vector
 +- Array Writer
 .  +- ColumnWriterIndex (for array as a whole)
 .  +- OffsetVectorWriter (A)
 .  .  +- Offset vector (B)
 .  +- ArrayElementWriterIndex
 .  +- ScalarWriter (D)
 .  .  +- ArrayElementWriterIndex
 .  .  +- Scalar vector (D)
 

The top group of objects point into the writer objects in the second group. Letters in parens show the connections.

To perform the roll-over, we must:

• Copy values from the current vectors to a set of new, look-ahead vectors.
• Swap buffers between the main and "backup" vectors, effectively moving the "full" batch to the sidelines, putting the look-ahead vectors into play in order to finish writing the current row.
• Update the writers to point to the look-ahead buffers, including the initial set of data copied into those vectors.
• Update the vector indexes to point to the next write positions after the values copied during roll-over.

Specified by:

rollover in interface VectorState

Parameters:

newCardinality - the number of outer elements to create in the look-ahead vector

harvestWithLookAhead

public void harvestWithLookAhead()

Description copied from interface: VectorState

A batch is being harvested after an overflow. Put the full batch back into the main vector so it can be harvested.

Specified by:

harvestWithLookAhead in interface VectorState

startBatchWithLookAhead

public void startBatchWithLookAhead()

Description copied from interface: VectorState

A new batch is starting while an look-ahead vector exists. Move the look-ahead buffers into the main vector to prepare for writing the rest of the 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

dump

public void dump(HierarchicalFormatter format)

Specified by:

dump in interface VectorState