Data Management and Query Processing in Semantic Web Databases

273 Pages·2011·11.762 MB·English

by  Sven Groppe (auth.)

Data Management and Query Processing
in Semantic Web Databases
.
Sven Groppe
Data Management
and Query Processing
in Semantic Web
Databases
SvenGroppe
InstituteofInformationSystems
UniversityofLu¨beck
RatzeburgerAllee160(Building64-2ndlevel)
23562Lu¨beck
Germany
groppe@ifis.uni-luebeck.de
ISBN978-3-642-19356-9 e-ISBN978-3-642-19357-6
DOI10.1007/978-3-642-19357-6
SpringerHeidelbergDordrechtLondonNewYork
ACMComputingClassification(1998):H.2,H.3,I.2
LibraryofCongressControlNumber:2011926984
# Springer-VerlagBerlinHeidelberg2011
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Contents
1 Introduction ............................................................... 1
1.1 MainTargetGroupoftheBook ....................................... 2
1.2 PrerequisitesNeededtoUnderstandtheBook ........................ 3
1.3 Content ................................................................. 3
1.4 LogicalOrganizationoftheBook ..................................... 4
1.5 StructureoftheChaptersandBookWebpage ........................ 4
2 SemanticWeb ............................................................. 7
2.1 Introduction ............................................................ 7
2.2 Overview ............................................................... 8
2.3 RDFData .............................................................. 9
2.3.1 N3Notation .................................................... 11
2.3.2 RDF/XML ..................................................... 13
2.4 OntologyLanguages .................................................. 13
2.5 OpenWorldAssumption ............................................. 16
2.6 NoUniqueNameAssumption ........................................ 17
2.7 SPARQLQueryLanguage ........................................... 17
2.7.1 LanguageConstructsofSPARQL ............................. 18
2.7.2 SPARQLProtocolforRDF ................................... 24
2.7.3 SPARQLQueryResultsXMLFormat ........................ 26
2.7.4 RDFStores ..................................................... 27
2.8 Rules .................................................................. 28
2.9 RelatedWork ......................................................... 31
2.9.1 RIFProcessing ................................................. 31
2.9.2 OptimizationsforRecursiveRules ............................ 33
2.10 SummaryandConclusions .......................................... 34
3 ExternalSortingandB+-Trees ......................................... 35
3.1 Motivation ............................................................ 35
3.2 B+-trees ............................................................... 36
3.2.1 PropertiesofB+-Trees ......................................... 37
v
vi Contents
3.2.2 Self-balancingPropertyofB+-Trees .......................... 38
3.2.3 Searching ....................................................... 39
3.2.4 PrefixSearchinCombinationwithSideways
InformationPassing ............................................ 39
3.2.5 Inserting ........................................................ 41
3.2.6 Deleting ........................................................ 43
3.2.7 B+-TreeConstructionfromalargeDataset ................... 45
3.3 Heap ................................................................... 45
3.4 (External)MergeSort ................................................ 47
3.5 ReplacementSelection ................................................ 48
3.6 ExternalChunksMergeSort ......................................... 50
3.7 DistributionSort ...................................................... 52
3.8 RDFDistributionSort ................................................ 53
3.9 ExperimentalAnalysis ................................................ 56
3.9.1 SP2BDataset ................................................... 57
3.9.2 YagoDataset ................................................... 58
3.10 SummaryandConclusions .......................................... 63
4 QueryProcessingOverview ............................................. 67
4.1 TheLUPOSDATESystem ........................................... 67
4.2 PhasesofQueryProcessing .......................................... 69
4.3 CoreSPARQL ......................................................... 73
4.3.1 DefiningCoreSPARQL ........................................ 73
4.3.2 TransformingSPARQLQueriesintoCoreSPARQL
Queries ......................................................... 74
4.3.3 CoreSPARQLGrammar ....................................... 77
4.4 RelatedWork ......................................................... 78
4.5 SummaryandConclusions ........................................... 78
5 LogicalOptimization .................................................... 79
5.1 LogicalAlgebra ....................................................... 79
5.1.1 SemanticsoftheLogicalAlgebraOperators .................. 81
5.2 LogicalOptimizationRules .......................................... 85
5.2.1 PushingFILTEROperators .................................... 85
5.2.2 SplittingandCommutativityofFILTEROperators .......... 87
5.2.3 ConstantandVariablePropagation ........................... 87
5.2.4 HeuristicQueryOptimizationUsingEquivalencyRules ..... 89
5.2.5 Cost-BasedOptimization ...................................... 90
5.2.6 Histograms ..................................................... 99
5.3 FurtherRelatedWork ............................................... 101
5.4 SummaryandConclusions ......................................... 101
6 PhysicalOptimization .................................................. 103
6.1 Motivation .......................................................... 104
6.2 RelatedWork ....................................................... 106
Contents vii
6.3 Indexing ............................................................. 108
6.3.1 BuildingIn-MemoryIndices ................................. 109
6.3.2 BuildingDisk-BasedIndices ................................. 110
6.4 PipeliningVersusMaterialization .................................. 116
6.4.1 Pipeline-Breaker .............................................. 116
6.4.2 SidewaysInformationPassing ................................ 116
6.5 JoinAlgorithms ..................................................... 117
6.5.1 Nested-LoopJoin ............................................. 117
6.5.2 MergeJoin .................................................... 120
6.5.3 IndexJoin ..................................................... 122
6.5.4 HashJoin ...................................................... 123
6.6 DynamicallyRestrictingTriplePatterns ........................... 126
6.7 SortingNumberingScheme ........................................ 129
6.7.1 JoinsWithoutPresortingNumbers ........................... 129
6.7.2 JoinswithPresortingNumbers ............................... 131
6.7.3 OptimizationofFastSorting ................................. 132
6.7.4 SortingforComplexJoins .................................... 132
6.7.5 AdditionalBenefitsfromSIPStrategies ..................... 135
6.8 Optional ............................................................. 136
6.8.1 MergeOptional ................................................ 136
6.9 DuplicateElimination .............................................. 137
6.9.1 DuplicateEliminationUsingHashing ........................ 137
6.9.2 DuplicateEliminationUsingSorting ......................... 138
6.9.3 DuplicateEliminationUsingPresortingNumbers ........... 138
6.10 CostModel ........................................................ 138
6.11 PerformanceEvaluation ........................................... 139
6.11.1 PerformanceEvaluationforIn-memoryDatabases ....... 139
6.11.2 PerformanceEvaluationforLarge-ScaleDatasets ........ 145
6.12 SummaryandConclusions ........................................ 152
7 Streams .................................................................. 155
7.1 Introduction ......................................................... 155
7.2 eBay ................................................................. 156
7.3 MonitoringeBayAuctions ......................................... 157
7.3.1 MonitoringSystem ........................................... 157
7.3.2 Demonstration ................................................ 158
7.3.3 StreamingSPARQLEngine .................................. 159
7.4 SpecialOperatorsforStreamProcessing ........................... 160
7.4.1 TypesofStreamOperators ................................... 160
7.4.2 TypesofWindowOperators .................................. 161
7.5 RelatedWork ....................................................... 161
7.5.1 DataStreamsinGeneral ...................................... 161
7.5.2 SemanticWebDataStreams ................................. 162
7.6 SummaryandConclusions ......................................... 162
viii Contents
8 ParallelDatabases ...................................................... 163
8.1 Motivation .......................................................... 163
8.2 TypesofParallelisms ............................................... 165
8.3 Amdahl’sLaw ...................................................... 167
8.4 ParallelMonitorsandBoundedBuffers ............................ 168
8.5 ParallelJoinUsingaDistributionThread .......................... 168
8.6 ParallelMergeJoinUsingPartitionedInput ....................... 169
8.7 ParallelComputationofOperands ................................. 172
8.8 PerformanceEvaluation ............................................ 173
8.9 PerformanceGainsandLoss ....................................... 175
8.10 SummaryandConclusions ........................................ 175
9 Inference ................................................................. 177
9.1 Introduction ......................................................... 177
9.2 RDFSchemaInferenceRules ...................................... 178
9.3 MaterializationofInferenceandConsequences
forQueryOptimization ............................................. 179
9.4 LogicalOptimizationforInference ................................ 180
9.5 PerformanceAnalysis .............................................. 187
9.6 RelatedWork ....................................................... 189
9.7 SummaryandConclusions ......................................... 189
10 VisualQueryLanguages ............................................... 191
10.1 Motivation ......................................................... 191
10.2 RelatedWork ...................................................... 193
10.3 RDFVisualEditor ................................................. 194
10.4 SPARQLVisualEditor ............................................ 194
10.5 Browser-LikeQueryCreation ..................................... 194
10.6 GeneratingCondensedDataView ................................ 196
10.7 RefiningQueries ................................................... 197
10.8 QueryFormulationDemo ......................................... 198
10.9 ComputationofSuggestedTriplePatternsforQuery
Refinement ......................................................... 199
10.10 SummaryandConclusions ....................................... 201
11 EmbeddedLanguages .................................................. 203
11.1 Motivation ......................................................... 203
11.2 RelatedWork ...................................................... 204
11.3 EmbeddingSemanticWebLanguagesIntoJAVA ............... 205
11.3.1 TheTypeSystem .......................................... 208
11.3.2 SubtypeTest ............................................... 210
11.3.3 SatisfiabilityTestofEmbeddedSPARQL
andSPARULQueries .................................... 215
11.3.4 DeterminationoftheQueryResultTypes ................ 217
11.4 SummaryandConclusions ........................................ 217
Contents ix
12 ComparisonoftheXMLandSemanticWebWorlds ................ 219
12.1 Introduction ........................................................ 219
12.2 ConceptsandVisions ............................................. 221
12.3 DataModels ....................................................... 221
12.4 SchemaandOntologyLanguages ................................. 222
12.5 QueryLanguages .................................................. 223
12.6 EmbeddingSPARQLintoXQuery/XSLT ........................ 226
12.6.1 EmbeddedSPARQL ....................................... 226
12.6.2 TranslationProcess ........................................ 229
12.6.3 ExperimentalAnalysis .................................... 235
12.7 EmbeddingXPathIntoSPARQL ................................. 240
12.7.1 TranslationofXPathSubqueriesIntoSPARQL
Queries ..................................................... 241
12.7.2 PerformanceAnalysis ..................................... 247
12.8 RelatedWork ...................................................... 248
12.9 SummaryandConclusions ........................................ 250
13 Summary,Conclusions,andFutureWork ........................... 251
13.1 PossibilitiesforFutureWork ...................................... 252
References .................................................................... 255
Index .......................................................................... 267