org.apache.drill.exec.physical.impl.TopN

Interface PriorityQueue

All Known Implementing Classes:

PriorityQueueTemplate

public interface PriorityQueue

Field Summary

Fields

Modifier and Type	Field and Description
static TemplateClassDefinition<PriorityQueue>	TEMPLATE_DEFINITION

Method Summary

Methods

Modifier and Type	Method and Description
void	add(RecordBatchData batch) The elements in the given batch are added to the priority queue.
void	cleanup() Releases all the memory consumed by the priority queue.
void	generate() This method must be called before fetching the final priority queue hyper batch and final Sv4 vector.
SelectionVector4	getFinalSv4() Retrieves the selection vector used to select the elements in the priority queue from the hyper batch provided by the getHyperBatch() method.
VectorContainer	getHyperBatch() Retrieves the final priority queue HyperBatch containing the results.
SelectionVector4	getSv4()
void	init(int limit, BufferAllocator allocator, boolean hasSv2) Initializes the priority queue.
void	resetQueue(VectorContainer container, SelectionVector4 vector4)

Field Detail

TEMPLATE_DEFINITION

static final TemplateClassDefinition<PriorityQueue> TEMPLATE_DEFINITION

Method Detail

add

void add(RecordBatchData batch)
         throws SchemaChangeException

The elements in the given batch are added to the priority queue. Note that the priority queue only retains the top elements that fit within the size specified by the init(int, BufferAllocator, boolean) method.

Parameters:

batch - The batch containing elements we want to add.

Throws:

SchemaChangeException

init

void init(int limit,
        BufferAllocator allocator,
        boolean hasSv2)
          throws SchemaChangeException

Initializes the priority queue. This method must be called before any other methods on the priority queue are called.

Parameters:

limit - The size of the priority queue.

allocator - The BufferAllocator to use when creating the priority queue.

hasSv2 - True when incoming batches have 2 byte selection vectors. False otherwise.

Throws:

SchemaChangeException

generate

void generate()
              throws SchemaChangeException

This method must be called before fetching the final priority queue hyper batch and final Sv4 vector.

Throws:

SchemaChangeException

getHyperBatch

VectorContainer getHyperBatch()

Retrieves the final priority queue HyperBatch containing the results. Note: this should be called after generate().

Returns:

The final priority queue HyperBatch containing the results.

getSv4

SelectionVector4 getSv4()

getFinalSv4

SelectionVector4 getFinalSv4()

Retrieves the selection vector used to select the elements in the priority queue from the hyper batch provided by the getHyperBatch() method. Note: this should be called after generate().

Returns:

The selection vector used to select the elements in the priority queue.

resetQueue

void resetQueue(VectorContainer container,
              SelectionVector4 vector4)
                throws SchemaChangeException

Throws:

SchemaChangeException

cleanup

void cleanup()

Releases all the memory consumed by the priority queue.