com.bigdata.rdf.sparql.ast

Class SolutionSetStatserator

java.lang.Object

com.bigdata.rdf.sparql.ast.SolutionSetStatserator

All Implemented Interfaces:

ICloseable, ICloseableIterator<IBindingSet[]>, Iterator<IBindingSet[]>

public class SolutionSetStatserator
extends Object
implements ICloseableIterator<IBindingSet[]>

Class populates an ISolutionSetStats object from a stream of solutions. The summary is available from getStats() once the source solutions have been fully consumed. TODO Compute the distinct values for each variable for which we have a binding, or at least the #of such values and offer a method to obtain the distinct values which could cache them. We can do the exact #of distinct values trivially for small solution sets. For very large solution sets this is more expensive and approximate techniques for obtaining the distinct set only when it is likely to be small would be appropriate.

Note that this must correctly handle TermId.mockIV(VTE)s.

Or compute a bloom filter for a statistical summary.

See Also:

Mock IV / TermId hashCode()/equals() problems

Field Summary

Fields

Modifier and Type	Field and Description
protected Set<IVariable<?>>	currentVars
protected Map<IVariable<?>,IConstant<?>>	firstBoundValue A map from the variable to the first bound value for that variable.
protected Set<IVariable<?>>	notAlwaysBound The set of variables which are NOT bound in at least one solution (e.g., MAYBE bound semantics).
protected Set<IVariable<?>>	notBoundThisSolution
protected Set<IVariable<?>>	notConstant The set of variables which have been proven to not be effective constants.
protected Set<IVariable<?>>	notMaterialized The set of variables whose IVCache association is NOT set is at least one solution in which the variable is bound.
protected long	nsolutions The #of solutions.
protected Set<IVariable<?>>	usedVars The set of variables observed across all solutions.

Constructor Summary

Constructors

Constructor and Description
SolutionSetStatserator(Iterator<IBindingSet[]> src)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the iterator, releasing any associated resources.
protected ISolutionSetStats	compile() Compile the statistics collected from the observed solutions.
protected void	filter(IBindingSet[] a) Compute incremental statistics from an observed chunk of solutions.
static ISolutionSetStats	get(IBindingSet[] bindingSets) Convenience method.
ISolutionSetStats	getStats() Return the compiled statistics.
boolean	hasNext()
IBindingSet[]	next()
void	remove()

Methods inherited from class java.lang.Object

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

Field Detail

nsolutions

protected long nsolutions

The #of solutions.

usedVars

protected final Set<IVariable<?>> usedVars

The set of variables observed across all solutions.

notAlwaysBound

protected final Set<IVariable<?>> notAlwaysBound

The set of variables which are NOT bound in at least one solution (e.g., MAYBE bound semantics).

notMaterialized

protected final Set<IVariable<?>> notMaterialized

The set of variables whose IVCache association is NOT set is at least one solution in which the variable is bound.

firstBoundValue

protected final Map<IVariable<?>,IConstant<?>> firstBoundValue

A map from the variable to the first bound value for that variable. This is used to identify variables which are effective constants (they are bound in the first solution and in each solution thereafter and always to the same value).

notConstant

protected final Set<IVariable<?>> notConstant

The set of variables which have been proven to not be effective constants. In order to be an effective constant, the variable must be bound in all solutions and it must be bound to the same value in each solution.

currentVars

protected final Set<IVariable<?>> currentVars

notBoundThisSolution

protected final Set<IVariable<?>> notBoundThisSolution

Constructor Detail

SolutionSetStatserator

public SolutionSetStatserator(Iterator<IBindingSet[]> src)

Method Detail

get

public static ISolutionSetStats get(IBindingSet[] bindingSets)

Convenience method.

Parameters:

bindingSets - The source solutions.

Returns:

The computed statistics.

filter

protected void filter(IBindingSet[] a)

Compute incremental statistics from an observed chunk of solutions.

compile

protected ISolutionSetStats compile()

Compile the statistics collected from the observed solutions.

Returns:

The compiled statistics.

getStats

public ISolutionSetStats getStats()

Return the compiled statistics.

Returns:

The compiled statistics.

Throws:

{@link - IllegalStateException} if the statistics have not yet been compiled (they are automatically compiled when the source iterator has been fully consumed).

close

public void close()

Description copied from interface: ICloseableIterator

Closes the iterator, releasing any associated resources. This method MAY be invoked safely if the iterator is already closed. Implementations of this interface MUST invoke ICloseableIterator.close() if Iterator.hasNext() method returns false to ensure that the iterator is closed (and its resources release) as soon as it is exhausted.

Note: Implementations that support Iterator.remove() MUST NOT eagerly close the iterator when it is exhausted since that would make it impossible to remove the last visited statement. Instead they MUST wait for an explicit ICloseableIterator.close() by the application.

Specified by:

close in interface ICloseable

Specified by:

close in interface ICloseableIterator<IBindingSet[]>

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<IBindingSet[]>

next

public IBindingSet[] next()

Specified by:

next in interface Iterator<IBindingSet[]>

remove

public void remove()

Specified by:

remove in interface Iterator<IBindingSet[]>