org.aksw.sparqlify.core.algorithms

Class CandidateViewSelectorBase<T extends IViewDef,C>

java.lang.Object

org.aksw.sparqlify.core.algorithms.CandidateViewSelectorBase<T,C>

Type Parameters:

T - The ViewDefinition type. Must inherit from IViewDef

I - Type for result items - i.e. when the recursion reaches its end, it gives the list of found view candidates to a function that can transform it into an object of type I

C - Context type used during recursion when looking for view candidates for quad patterns. Intended to track custom information for unsatisfiability determination.

All Implemented Interfaces:

CandidateViewSelector<T>

Direct Known Subclasses:

CandidateViewSelectorImpl, CandidateViewSelectorRestructify

public abstract class CandidateViewSelectorBase<T extends IViewDef,C>
extends Object
implements CandidateViewSelector<T>

Author:

raven

Constructor Summary

Constructors

Constructor and Description
CandidateViewSelectorBase()

Method Summary

Modifier and Type	Method and Description
com.hp.hpl.jena.sparql.algebra.Op	_getApplicableViews(com.hp.hpl.jena.sparql.algebra.Op op) Given a sparql query in quad form, this method replaces (sub sets of) quad patterns with view instances (view patterns) The method also passes the filter conditions that an op must satisfy.
com.hp.hpl.jena.sparql.algebra.Op	_getApplicableViews(com.hp.hpl.jena.sparql.algebra.Op op, RestrictionManagerImpl restrictions)
void	addView(T viewDef)
C	createContext(C baseContext, ViewInstance<T> viewInstance) Optionally override this method to track custom information during the recursion of candidate selection of quad patterns
abstract com.hp.hpl.jena.sparql.algebra.Op	createOp(OpQuadPattern2 opQuadPattern, List<RecursionResult<T,C>> viewInstances)
static <T extends IViewDef> ViewInstance<T>	createViewInstance(RestrictionManagerImpl subRestrictions, com.hp.hpl.jena.sparql.core.Quad queryQuad, ViewQuad<T> viewQuad) Checks whether the view quad is consistent with the current constraints
static StartsWithConstraint	deriveConstraint(com.hp.hpl.jena.sparql.expr.E_StrConcat expr)
static StartsWithConstraint	deriveConstraint(E_StrConcatPermissive expr)
static Constraint	deriveConstraint(com.hp.hpl.jena.sparql.expr.Expr expr)
static VariableConstraint	deriveIsPrefixOfConstraint(com.hp.hpl.jena.sparql.expr.Expr a, com.hp.hpl.jena.sparql.expr.Expr b) If a variable equals a (uri or string) constant, it means that the view must provide a prefix for that value.
static VariableConstraint	deriveViewLookupConstraint(com.hp.hpl.jena.sparql.expr.Expr expr) Returns IsPrefixOf Constraints for equality expressions between variables and constants.
static RestrictionManagerImpl	filterRestrictionsBound(RestrictionManagerImpl restrictions) Create a new retrictions manager, where "bound" retrictions are removed
Set<ViewQuad<T>>	findCandidates(com.hp.hpl.jena.sparql.core.Quad quad, RestrictionManagerImpl restrictions) TODO: This method is far from optimal performance right now: We need to consider prefix-set-restrictions of the variables during the lookup in order to rule out returning to many view-quad candidates.
org.aksw.commons.util.Pair<NavigableMap<Integer,Set<com.hp.hpl.jena.sparql.core.Quad>>,Map<com.hp.hpl.jena.sparql.core.Quad,Set<ViewQuad<T>>>>	findQuadWithFewestViewCandidates(com.hp.hpl.jena.sparql.core.QuadPattern queryQuads, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpAssign op, RestrictionManagerImpl _restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpConditional op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpDisjunction op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpDistinct op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpExtend op, RestrictionManagerImpl _restrictions) Extend defines now variables and is therefore similar to a VarDefinition.
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpFilter op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpGroup op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpJoin op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpLeftJoin op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpOrder op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpProject op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(OpQuadPattern2 op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpSequence op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpSlice op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpTopN op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpUnion op, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	getApplicableViews(com.hp.hpl.jena.query.Query query)
List<RecursionResult<T,C>>	getApplicableViewsBase(OpQuadPattern2 op, RestrictionManagerImpl restrictions) Order the quads of the quadPattern by selectivity.
void	getApplicableViewsRec2(int index, List<com.hp.hpl.jena.sparql.core.Quad> quadOrder, Set<ViewQuad<T>> viewQuads, Map<com.hp.hpl.jena.sparql.core.Quad,Set<ViewQuad<T>>> candidates, RestrictionManagerImpl restrictions, NestedStack<ViewInstance<T>> instances, List<RecursionResult<T,C>> result, C baseContext)
static <T extends IViewDef> List<String>	getCandidateNames(NestedStack<ViewInstance<T>> instances)
static List<RestrictionManagerImpl>	getRestrictions(com.hp.hpl.jena.sparql.algebra.Op op)
static void	getRestrictions(com.hp.hpl.jena.sparql.algebra.Op op, Collection<RestrictionManagerImpl> result) Returns a disjunction (list) of restrictions that apply for a given node
static RestrictionManagerImpl	getRestrictions2(com.hp.hpl.jena.sparql.algebra.Op op)
static RdfTermType	getType(com.hp.hpl.jena.graph.Node node, RestrictionManagerImpl restrictions)
Collection<T>	getViews()
Map<String,Constraint>	inferColumnConstraints(com.hp.hpl.jena.sparql.core.Quad quad, RestrictionImpl[] termRestriction, Clause clause)
static <T extends IViewDef> boolean	isSatisfiable(List<ViewInstance<T>> list) TODO FIX THIS
T	normalizeView(T view) Override this function to transform the view before actually indexing it
com.hp.hpl.jena.sparql.algebra.Op	processJoinSplitLhs(com.hp.hpl.jena.sparql.algebra.Op left, com.hp.hpl.jena.sparql.algebra.Op right, Iterable<com.hp.hpl.jena.sparql.expr.Expr> exprs, RestrictionManagerImpl restrictions, boolean isLeftJoin)
com.hp.hpl.jena.sparql.algebra.Op	processLeftJoin(com.hp.hpl.jena.sparql.algebra.Op left, com.hp.hpl.jena.sparql.algebra.Op right, Iterable<com.hp.hpl.jena.sparql.expr.Expr> exprs, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.op.OpLeftJoin	processLeftJoinDirect(com.hp.hpl.jena.sparql.algebra.Op left, com.hp.hpl.jena.sparql.algebra.Op right, Iterable<com.hp.hpl.jena.sparql.expr.Expr> exprs, RestrictionManagerImpl restrictions)
com.hp.hpl.jena.sparql.algebra.Op	processOpExtend(com.hp.hpl.jena.sparql.algebra.Op subOp, com.hp.hpl.jena.sparql.core.VarExprList varExprs, RestrictionManagerImpl _restrictions)

Methods inherited from class java.lang.Object

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

Constructor Detail

CandidateViewSelectorBase

public CandidateViewSelectorBase()

Parameters:

opMappingRewriter - May be null. If given, we can do rewrites during the SQL generation to prune empty result mappings early.

Method Detail

createOp

public abstract com.hp.hpl.jena.sparql.algebra.Op createOp(OpQuadPattern2 opQuadPattern,
                                                           List<RecursionResult<T,C>> viewInstances)

createContext

public C createContext(C baseContext,
                       ViewInstance<T> viewInstance)
                throws UnsatisfiabilityException

Optionally override this method to track custom information during the recursion of candidate selection of quad patterns

Parameters:

baseContext -

viewInstance -

Returns:

Throws:

UnsatisfiabilityException

addView

public void addView(T viewDef)

Specified by:

addView in interface CandidateViewSelector<T extends IViewDef>

deriveConstraint

public static Constraint deriveConstraint(com.hp.hpl.jena.sparql.expr.Expr expr)

deriveConstraint

public static StartsWithConstraint deriveConstraint(com.hp.hpl.jena.sparql.expr.E_StrConcat expr)

deriveConstraint

public static StartsWithConstraint deriveConstraint(E_StrConcatPermissive expr)

getType

public static RdfTermType getType(com.hp.hpl.jena.graph.Node node,
                                  RestrictionManagerImpl restrictions)

normalizeView

public T normalizeView(T view)

Override this function to transform the view before actually indexing it

Parameters:

view -

Returns:

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.query.Query query)

Specified by:

getApplicableViews in interface CandidateViewSelector<T extends IViewDef>

deriveIsPrefixOfConstraint

public static VariableConstraint deriveIsPrefixOfConstraint(com.hp.hpl.jena.sparql.expr.Expr a,
                                                            com.hp.hpl.jena.sparql.expr.Expr b)

If a variable equals a (uri or string) constant, it means that the view must provide a prefix for that value.

Parameters:

a -

b -

Returns:

deriveViewLookupConstraint

public static VariableConstraint deriveViewLookupConstraint(com.hp.hpl.jena.sparql.expr.Expr expr)

Returns IsPrefixOf Constraints for equality expressions between variables and constants. Used for looking up view candidates. Not used for satisfiability checks.

Parameters:

expr -

Returns:

getApplicableViewsBase

public List<RecursionResult<T,C>> getApplicableViewsBase(OpQuadPattern2 op,
                                                         RestrictionManagerImpl restrictions)

Order the quads of the quadPattern by selectivity. Iterate the quads in order, and for each quad, do a lookup of the views that may yield answers to it. So for each quad we get a set of candidate bindings to the views. Binding is a mapping from query-var to a set of view variables/constant The view varibale may have constraints on it, which carry over to the query variable. So given Create View x ... {?x a Class . } With ?x.value prefix "foo" a query Select {?s ?p ?o } and a binding(?s = ?x), then we can infer the constraint on ?x.value prefix "foo" So if there is a second pattern { ?x a Class. ?x label ?z } Then we can use this constraint on the lookup at the second pattern. Note that the selectivity of query quad pattern change with the bindings, so we should be able to quickly update the selectivity of the quads in the presence of bindings. Another note: Maybe we could treat constants as specially delimited prefixes, such as 'aaaa' = prefix 'aaaaa$' = constant

inferColumnConstraints

public Map<String,Constraint> inferColumnConstraints(com.hp.hpl.jena.sparql.core.Quad quad,
                                                     RestrictionImpl[] termRestriction,
                                                     Clause clause)

findCandidates

public Set<ViewQuad<T>> findCandidates(com.hp.hpl.jena.sparql.core.Quad quad,
                                       RestrictionManagerImpl restrictions)

TODO: This method is far from optimal performance right now: We need to consider prefix-set-restrictions of the variables during the lookup in order to rule out returning to many view-quad candidates.

Parameters:

quad -

restrictions -

Returns:

findQuadWithFewestViewCandidates

public org.aksw.commons.util.Pair<NavigableMap<Integer,Set<com.hp.hpl.jena.sparql.core.Quad>>,Map<com.hp.hpl.jena.sparql.core.Quad,Set<ViewQuad<T>>>> findQuadWithFewestViewCandidates(com.hp.hpl.jena.sparql.core.QuadPattern queryQuads,
                                                                                                                                                                                       RestrictionManagerImpl restrictions)

getCandidateNames

public static <T extends IViewDef> List<String> getCandidateNames(NestedStack<ViewInstance<T>> instances)

createViewInstance

public static <T extends IViewDef> ViewInstance<T> createViewInstance(RestrictionManagerImpl subRestrictions,
                                                                      com.hp.hpl.jena.sparql.core.Quad queryQuad,
                                                                      ViewQuad<T> viewQuad)

Checks whether the view quad is consistent with the current constraints

Parameters:

restrictions -

queryQuad -

viewQuad -

Returns:

getApplicableViewsRec2

public void getApplicableViewsRec2(int index,
                                   List<com.hp.hpl.jena.sparql.core.Quad> quadOrder,
                                   Set<ViewQuad<T>> viewQuads,
                                   Map<com.hp.hpl.jena.sparql.core.Quad,Set<ViewQuad<T>>> candidates,
                                   RestrictionManagerImpl restrictions,
                                   NestedStack<ViewInstance<T>> instances,
                                   List<RecursionResult<T,C>> result,
                                   C baseContext)

Parameters:

index -

quadOrder -

viewQuads - The viewQuads provided by the parent invocation - with any restrictions encountered during the rewrite taken into account

candidates - The viewQuads here are the ones from only analyzing the query filter In some cases (small candidate sets) it might be faster filtering this set of view candidates, rather than doing a new lookup.

restrictions -

result -

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(OpQuadPattern2 op,
                                                            RestrictionManagerImpl restrictions)

isSatisfiable

public static <T extends IViewDef> boolean isSatisfiable(List<ViewInstance<T>> list)

TODO FIX THIS

Parameters:

list -

Returns:

_getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op _getApplicableViews(com.hp.hpl.jena.sparql.algebra.Op op)

Given a sparql query in quad form, this method replaces (sub sets of) quad patterns with view instances (view patterns) The method also passes the filter conditions that an op must satisfy.

Parameters:

op -

Returns:

_getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op _getApplicableViews(com.hp.hpl.jena.sparql.algebra.Op op,
                                                             RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpSequence op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpTopN op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpDisjunction op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpProject op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpOrder op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpGroup op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpExtend op,
                                                            RestrictionManagerImpl _restrictions)

Extend defines now variables and is therefore similar to a VarDefinition. Below is outdated. We treat OpExtend as a filter for now TODO This breaks for instance Count(*) as Jena also does renaming with extend: Jena generates Project(?c, Extend(?c, ?x, Group(Count(*) As ?x))) So in this case, extend creates a new alias for a variable

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpAssign op,
                                                            RestrictionManagerImpl _restrictions)

processOpExtend

public com.hp.hpl.jena.sparql.algebra.Op processOpExtend(com.hp.hpl.jena.sparql.algebra.Op subOp,
                                                         com.hp.hpl.jena.sparql.core.VarExprList varExprs,
                                                         RestrictionManagerImpl _restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpFilter op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpUnion op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpJoin op,
                                                            RestrictionManagerImpl restrictions)

filterRestrictionsBound

public static RestrictionManagerImpl filterRestrictionsBound(RestrictionManagerImpl restrictions)

Create a new retrictions manager, where "bound" retrictions are removed

Parameters:

restrictions -

Returns:

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpLeftJoin op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpConditional op,
                                                            RestrictionManagerImpl restrictions)

processLeftJoin

public com.hp.hpl.jena.sparql.algebra.Op processLeftJoin(com.hp.hpl.jena.sparql.algebra.Op left,
                                                         com.hp.hpl.jena.sparql.algebra.Op right,
                                                         Iterable<com.hp.hpl.jena.sparql.expr.Expr> exprs,
                                                         RestrictionManagerImpl restrictions)

processJoinSplitLhs

public com.hp.hpl.jena.sparql.algebra.Op processJoinSplitLhs(com.hp.hpl.jena.sparql.algebra.Op left,
                                                             com.hp.hpl.jena.sparql.algebra.Op right,
                                                             Iterable<com.hp.hpl.jena.sparql.expr.Expr> exprs,
                                                             RestrictionManagerImpl restrictions,
                                                             boolean isLeftJoin)

processLeftJoinDirect

public com.hp.hpl.jena.sparql.algebra.op.OpLeftJoin processLeftJoinDirect(com.hp.hpl.jena.sparql.algebra.Op left,
                                                                          com.hp.hpl.jena.sparql.algebra.Op right,
                                                                          Iterable<com.hp.hpl.jena.sparql.expr.Expr> exprs,
                                                                          RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpSlice op,
                                                            RestrictionManagerImpl restrictions)

getApplicableViews

public com.hp.hpl.jena.sparql.algebra.Op getApplicableViews(com.hp.hpl.jena.sparql.algebra.op.OpDistinct op,
                                                            RestrictionManagerImpl restrictions)

getRestrictions2

public static RestrictionManagerImpl getRestrictions2(com.hp.hpl.jena.sparql.algebra.Op op)

getRestrictions

public static List<RestrictionManagerImpl> getRestrictions(com.hp.hpl.jena.sparql.algebra.Op op)

getRestrictions

public static void getRestrictions(com.hp.hpl.jena.sparql.algebra.Op op,
                                   Collection<RestrictionManagerImpl> result)

Returns a disjunction (list) of restrictions that apply for a given node

getViews

public Collection<T> getViews()

Specified by:

getViews in interface CandidateViewSelector<T extends IViewDef>