com.yahoo.sketches.theta

Class CompactSketch

java.lang.Object

com.yahoo.sketches.theta.Sketch

com.yahoo.sketches.theta.CompactSketch

public abstract class CompactSketch
extends Sketch

The parent class of all the CompactSketches. CompactSketches are never created directly. They are created as a result of the compact() method of an UpdateSketch or as a result of a getResult() of a SetOperation.

A CompactSketch is the simplist form of a Theta Sketch. It consists of a compact list (i.e., no intervening spaces) of hash values, which may be ordered or not, a value for theta and a seed hash. A CompactSketch is read-only, and the space required when stored is only the space required for the hash values and 8 to 24 bytes of preamble. An empty CompactSketch consumes only 8 bytes.

Author:

Lee Rhodes

Method Summary

Modifier and Type	Method and Description
Family	getFamily() Returns the Family that this sketch belongs to
int	getRetainedEntries(boolean valid) Returns the number of entries that have been retained by the sketch.
boolean	isCompact() Returns true if this sketch is in compact form.
boolean	isEmpty() See Empty

Methods inherited from class com.yahoo.sketches.theta.Sketch

getCountLessThanTheta, getCurrentBytes, getEstimate, getLowerBound, getMaxCompactSketchBytes, getMaxUpdateSketchBytes, getRetainedEntries, getSerializationVersion, getTheta, getUpperBound, heapify, heapify, isDirect, isEstimationMode, isOrdered, toByteArray, toString, toString, wrap, wrap

Methods inherited from class java.lang.Object

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

Method Detail

getRetainedEntries

public int getRetainedEntries(boolean valid)

Description copied from class: Sketch

Returns the number of entries that have been retained by the sketch.

Specified by:

getRetainedEntries in class Sketch

Parameters:

valid - if true, returns the number of valid entries, which are less than theta and used for estimation. Otherwise, return the number of all entries, valid or not, that are currently in the internal sketch cache.

Returns:

the number of retained entries

isEmpty

public boolean isEmpty()

Description copied from class: Sketch

See Empty

Specified by:

isEmpty in class Sketch

Returns:

true if empty.

getFamily

public Family getFamily()

Description copied from class: Sketch

Returns the Family that this sketch belongs to

Specified by:

getFamily in class Sketch

Returns:

the Family that this sketch belongs to

isCompact

public boolean isCompact()

Description copied from class: Sketch

Returns true if this sketch is in compact form.

Specified by:

isCompact in class Sketch

Returns:

true if this sketch is in compact form.