com.yahoo.bullet.querying.aggregations.sketches

Class DualSketch

java.lang.Object

com.yahoo.bullet.querying.aggregations.sketches.Sketch

com.yahoo.bullet.querying.aggregations.sketches.DualSketch

Direct Known Subclasses:

KMVSketch, QuantileSketch

public abstract class DualSketch
extends Sketch

This class wraps sketches that need a separate sketch for update and union operations. It manages the metadata relating to managing the common operations relating to managing dual sketches. All sketches inheriting this must call update(), union() and reset() when performing the respective operations. It must also call merge() before performing any operations that change data in the sketch such as getting metadata or results or resetting.

Field Summary

Fields inherited from class com.yahoo.bullet.querying.aggregations.sketches.Sketch

provider

Constructor Summary

Constructors

Constructor and Description
DualSketch()

Method Summary

Modifier and Type	Method and Description
protected void	merge() This method must be called before getting any kind of data out of the sketch.
protected abstract void	mergeBothSketches() Merge and reset both the update sketch and the union sketch into the result.
protected abstract void	mergeUnionSketch() Merge and reset just the union sketch into the result.
protected abstract void	mergeUpdateSketch() Merge and reset just the update sketch into the result.
void	reset() Resets the Sketch to the original state.
protected void	union() This method must be called after a Sketch.union(byte[]).
protected abstract boolean	unionedExistingResults() Merge the existing result into the union sketch if needed and return a boolean if the union was done.
protected void	update() This method must be called after an update operation.

Methods inherited from class com.yahoo.bullet.querying.aggregations.sketches.Sketch

addMetadata, getFamily, getMetadata, getRecords, getResult, getSize, isEstimationMode, serialize, union

Methods inherited from class java.lang.Object

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

Constructor Detail

DualSketch

public DualSketch()

Method Detail

update

protected void update()

This method must be called after an update operation.

union

protected void union()

This method must be called after a Sketch.union(byte[]).

merge

protected void merge()

This method must be called before getting any kind of data out of the sketch. This calls the appropriate driver methods to tell a subclass whether it needs to merge its two sketches (mergeBothSketches(), or merge its union sketch (mergeUnionSketch() or just the update sketch (mergeUpdateSketch(). It will also ask to add any existing merged results back into the union sketch (unionedExistingResults()). _ This method is idempotent and will not recollect till a data changing operation has been performed, such as an update, union or a reset. This is why you must call the appropriate methods (update(), union(), reset()) defined in this class when performing those operations.

mergeBothSketches

protected abstract void mergeBothSketches()

Merge and reset both the update sketch and the union sketch into the result.

mergeUpdateSketch

protected abstract void mergeUpdateSketch()

Merge and reset just the update sketch into the result.

mergeUnionSketch

protected abstract void mergeUnionSketch()

Merge and reset just the union sketch into the result.

unionedExistingResults

protected abstract boolean unionedExistingResults()

Merge the existing result into the union sketch if needed and return a boolean if the union was done.

Returns:

A boolean denoting whether the union was done.

reset

public void reset()

Resets the Sketch to the original state. The old results are lost. You should call this after you call Sketch.serialize() or Sketch.getResult(String, Map) if you want to add more data to the sketch. Call this after your reset operations to reset the metadata relating to storing two sketches. You should reset or remove all your sketches here.

Specified by:

reset in class Sketch