Package io.trino.operator

Class GroupedTopNRowNumberAccumulator

java.lang.Object

io.trino.operator.GroupedTopNRowNumberAccumulator

public class GroupedTopNRowNumberAccumulator
extends Object

Memory Layout:

          +--------------------+   +--------------+
          |GroupIdToHeapBuffer |   |HeapNodeBuffer|
          +--------------------+   +--------------+
 Group1+->+RootNodeIndex1+-------->+RowID1        |
          |RootNodeIndex2      |   |LeftChild1+-----+
          |...                 |   |RightChild1   | |
          +--------------------+   |RowID2    <-----+
          |HeapSize1           |   |LeftChild2    |
          |HeapSize2           |   |RightChild2   |
          |...                 |   |...           |
          +--------------------+   +--------------+
 

Constructor Summary

Constructors

Constructor	Description
GroupedTopNRowNumberAccumulator(RowIdComparisonStrategy strategy, int topN, LongConsumer rowIdEvictionListener)

Method Summary

Modifier and Type	Method	Description
boolean	add(long groupId, RowReference rowReference)	Add the specified row to this accumulator.
long	drainTo(long groupId, LongBigArray rowIdOutput)	Drain the contents of groupId from this accumulator to the provided output row ID buffer.
long	sizeOf()

Methods inherited from class java.lang.Object

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

Constructor Detail

GroupedTopNRowNumberAccumulator

public GroupedTopNRowNumberAccumulator(RowIdComparisonStrategy strategy,
                                       int topN,
                                       LongConsumer rowIdEvictionListener)

Method Detail

sizeOf

public long sizeOf()

add

public boolean add(long groupId,
                   RowReference rowReference)

Add the specified row to this accumulator.

This may trigger row eviction callbacks if other rows have to be evicted to make space.

Returns:

true if this row was incorporated, false otherwise

drainTo

public long drainTo(long groupId,
                    LongBigArray rowIdOutput)

Drain the contents of groupId from this accumulator to the provided output row ID buffer.

Rows will be presented in increasing rank order. Draining will not trigger any row eviction callbacks. After this method completion, the Accumulator will contain zero rows for the specified groupId.

Returns:

number of rows deposited to the output buffer