com.bigdata.bop.joinGraph.rto

Class Vertex

java.lang.Object

com.bigdata.bop.joinGraph.rto.Vertex

All Implemented Interfaces:

Serializable

public class Vertex
extends Object
implements Serializable

A vertex of the join graph is an annotated relation (this corresponds to an IPredicate with additional annotations to support the adaptive query optimization algorithm).

The unique identifier for a Vertex (within a given join graph) is the BOp.Annotations#BOP_ID decorating its IPredicate. hashCode() is defined in terms of this unique identifier so we can readily detect when a Set already contains a given Vertex.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
IPredicate<?>	pred The IPredicate associated with the Vertex.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object o) Equals is based on a reference test.
int	hashCode() The hash code is just the BOp.Annotations#BOP_ID of the associated IPredicate.
void	sample(QueryEngine queryEngine, int limit, SampleIndex.SampleType sampleType) Take a sample of the vertex, updating sample as a side-effect.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

pred

public final IPredicate<?> pred

The IPredicate associated with the Vertex. This basically provides the information necessary to select an appropriate access path.

Method Detail

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object o)

Equals is based on a reference test.

Overrides:

equals in class Object

hashCode

public int hashCode()

The hash code is just the BOp.Annotations#BOP_ID of the associated IPredicate.

Overrides:

hashCode in class Object

sample

public void sample(QueryEngine queryEngine,
          int limit,
          SampleIndex.SampleType sampleType)

Take a sample of the vertex, updating sample as a side-effect. If the sample is already exact, then this is a NOP. If the vertex was already sampled to that limit, then this is a NOP (you have to raise the limit to re-sample the vertex).

Parameters:

limit - The sample cutoff.