ISO/IEC 39075:2024

International
Standard
ISO/IEC 39075
First edition
Information technology — Database
2024-04
languages — GQL
Technologies de l'information — Langages de base de
données — GQL
Reference number
© ISO/IEC 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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© ISO/IEC 2024 – All rights reserved
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ISO/IEC39075:2024(en)
Contents Page
Foreword.xiv
Introduction.xv
1 Scope.1
2 Normativereferences.2
3 Termsanddefinitions.3
3.1 Generaltermsanddefinitions.3
3.2 GQL-environmenttermsanddefinitions.4
3.3 GQL-catalogtermsanddefinitions.6
3.4 Graphtermsanddefinitions.7
3.5 Procedureandcommandtermsanddefinitions.9
3.6 Generalsyntaxtermsanddefinitions.12
3.7 Graphpatterntermsanddefinitions.14
3.8 Valuetermsanddefinitions.15
3.9 Typetermsanddefinitions.17
3.10 Temporaltermsanddefinitions.19
4 Concepts.21
4.1 Useofterms.21
4.2 GQL-environmentsandtheircomponents.21
4.2.1 GeneraldescriptionofGQL-environments.21
4.2.2 GQL-agents.22
4.2.3 GQL-implementations.22
4.2.3.1 IntroductiontoGQL-implementations.22
4.2.3.2 GQL-clients.23
4.2.3.3 GQL-servers.23
4.2.4 Basicsecuritymodel.24
4.2.4.1 Principals.24
4.2.4.2 Authorizationidentifiersandprivileges.24
4.2.5 GQL-catalog.24
4.2.5.1 GeneraldescriptionoftheGQL-catalog.24
4.2.5.2 GQL-directories.25
4.2.5.3 GQL-schemas.26
4.2.6 GQL-data.27
4.3 GQL-objects.27
4.3.1 GeneralintroductiontoGQL-objects.27
4.3.2 ReferencestoGQL-schemasandGQL-objects.27
4.3.3 Primaryobjectsandsecondaryobjects.28
4.3.4 Propertiesandsupportedpropertyvaluetypes.28
4.3.5 Graphs.29
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4.3.5.1 Introductiontographs.29
4.3.5.2 Graphdescriptors.30
4.3.6 Bindingtables.30
4.4 Values.32
4.4.1 Generalinformationaboutvalues.32
4.4.2 Comparable values.32
4.4.3 Propertiesofdistinctvalues.32
4.4.4 Referencevalues.33
4.4.5 Materialvaluesandthenullvalue.33
4.5 GQL-sessions.33
4.5.1 GeneraldescriptionofGQL-sessions.33
4.5.2 Session contexts.34
4.5.2.1 Introductiontosessioncontexts.34
4.5.2.2 Sessioncontextcreation.35
4.5.2.3 Sessioncontextmodification.35
4.6 GQL-transactions.35
4.6.1 GeneraldescriptionofGQL-transactions.35
4.6.2 Transactiondemarcation.36
4.6.3 Transaction isolation.37
4.6.4 Encompassingtransactionbelongingtoanexternalagent.37
4.7 GQL-requestsandGQL-programs.38
4.7.1 GeneraldescriptionofGQL-requestsandGQL-programs.38
4.7.2 GQL-requestcontexts.38
4.7.2.1 IntroductiontoGQL-requestcontexts.38
4.7.2.2 GQL-requestcontextcreation.38
4.7.2.3 GQL-requestcontextmodification.39
4.7.3 ExecutionofGQL-requests.39
4.7.4 Workingschemareferences.40
4.7.5 Workinggraphsite.41
4.7.6 Executionstack.41
4.7.7 Operations.41
4.8 Execution contexts.42
4.8.1 Generaldescriptionofexecutioncontexts.42
4.8.2 Executioncontextcreationandinitialization.44
4.8.3 Executioncontextmodification.45
4.8.4 Execution outcomes.45
4.9 Diagnosticinformation.46
4.9.1 Introductiontodiagnosticinformation.46
4.9.2 GQL-status objects.46
4.9.3 Conditions.47
4.10 Proceduresandcommands.49
4.10.1 Generaldescriptionofproceduresandcommands.49
4.10.2 Procedures.49
4.10.2.1 Generaldescriptionofprocedures.49
4.10.2.2 Namedproceduredescriptors.50
4.10.2.3 Procedureexecution.50
4.10.2.4 Proceduresclassifiedbykindofsideeffects.50
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4.10.3 Commands.51
4.10.4 GQL-procedures.51
4.10.4.1 IntroductiontoGQL-procedures.51
4.10.4.2 Bindingvariablesandgeneralparameters.51
4.10.4.3 Statements.52
4.10.4.4 Statementsclassifiedbyuseofworkinggraphsites.52
4.10.4.5 Statementsclassifiedbyfunction.52
4.11 Graphpatternmatching.53
4.11.1 Summaryofgraphpatternmatching.53
4.11.2 Paths.53
4.11.3 Pathpatterns.54
4.11.4 Graphpatternvariables.55
4.11.5 Referencestographpatternvariables.56
4.11.6 Pathpatternmatching.57
4.11.7 Path modes.58
4.11.8 Selectivepathsearchprefixes.59
4.11.9 Matchmodes.59
4.12 Data types.59
4.12.1 Generalintroductiontodatatypesandbasetypes.59
4.12.2 Majorclassesofdatatypes.60
4.12.3 Datatypedescriptors.62
4.12.4 Namingofdatatypesandbasetypes.62
4.12.5 Material,nullable,andimmaterialdatatypes.63
4.12.6 Mostspecificstaticvaluetypeandstaticbasetype.63
4.12.7 Openandcloseddatatypes.63
4.12.8 Additionalterminologyrelatedtodatatypes.64
4.13 GQL-objecttypes.64
4.13.1 IntroductiontoGQL-objecttypesandrelatedbasetypes.64
4.13.2 Graphtypesandgraphelementtypes.65
4.13.2.1 Introductiontographtypesandgraphelementtypes.65
4.13.2.2 Graphtypedescriptors.65
4.13.2.3 Node types.66
4.13.2.4 Edgetypes.67
4.13.2.5 Property types.68
4.13.2.6 Keylabelsets.69
4.13.2.7 Structuralconsistencyofelementtypes.69
4.13.3 Bindingtabletypes.70
4.14 Dynamicuniontypes.71
4.14.1 Introductiontodynamicuniontypesandthedynamicbasetype.71
4.14.2 Dynamicuniondatatypedescriptors.71
4.14.3 Characteristicsofdynamicuniontypes.71
4.14.4 Dynamicgenerationoftypetestsandcasts.72
4.14.4.1 Introductiontodynamicgenerationoftypetestsandcastsfors.72
4.14.4.2 Dynamicgenerationoftypetestsandstrictcastsforawithoutoperands.72
4.14.4.3 Dynamicgenerationoftypetestsandstrictcastsforawithoperands.73
4.14.4.4 Dynamicgenerationofadditionaltypetestsandlaxcastsfora.75
4.15 Constructedvaluetypes.75
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4.15.1 Introductiontoconstructedvaluetypesandrelatedbasetypes.75
4.15.2 Pathvaluetypes.76
4.15.3 Listvaluetypes.76
4.15.4 Record types.77
4.16 Predefinedvaluetypes.79
4.16.1 Introductiontopredefinedvaluetypesandrelatedbasetypes.79
4.16.2 Boolean types.81
4.16.3 Characterstringtypes.82
4.16.3.1 Introductiontocharacterstrings.82
4.16.3.2 Collations.83
4.16.4 Bytestringtypes.84
4.16.5 Numerictypes.85
4.16.5.1 Introductiontonumbers.85
4.16.5.2 Characteristicsofnumbers.85
4.16.5.3 Binaryexactnumerictypes.87
4.16.5.4 Decimalexactnumerictypes.88
4.16.5.5 Approximatenumerictypes.89
4.16.6 Temporaltypes.90
4.16.6.1 Introductiontotemporaldata.90
4.16.6.2 Temporalinstanttypes.90
4.16.6.3 Temporaldurationtypes.91
4.16.6.4 Operatorsinvolvingvaluesoftemporaltypes.92
4.16.7 Referencevaluetypes.93
4.16.8 Immaterialvaluetypes:nulltypeandemptytype.94
4.17 Sites.94
4.17.1 Generaldescriptionofsites.94
4.17.2 Staticanddynamicsites.95
4.17.3 Assignmentandstoreassignment.95
4.17.4 Nullability.95
4.17.4.1 Introductiontonullability.95
4.17.4.2 Nullability requirements.96
4.17.4.3 Nullabilityinference.96
5 Notationandconventions.97
5.1 NotationtakenfromTheUnicode®Standard.97
5.2 Notation.97
5.3 Conventions.98
5.3.1 Specificationofsyntacticelements.98
5.3.2 Useofterms.99
5.3.2.1 Syntactic containment.99
5.3.2.2 Keywordsands.100
5.3.2.3 Termsdenotingrulerequirements.100
5.3.2.4 Ruleevaluationorder.100
5.3.2.5 Conditional rules.101
5.3.2.6 Syntactic substitution.102
5.3.3 Descriptors.102
5.3.4 Subclausesusedassubroutines.103
5.3.5 Document typography.103
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5.3.6 Index typography.103
5.3.7 FeatureIDandFeatureName.104
6 .105
7 Sessionmanagement.107
7.1 .107
7.2 .111
7.3 .113
7.4 .114
8 Transaction management.115
8.1 .115
8.2 .116
8.3 .117
8.4 .118
9 Procedure specification.119
9.1 .119
9.2 .121
10 Variable definitions.125
10.1 .125
10.2 .127
10.3 .129
11 Object expressions.131
11.1 .131
11.2 .133
11.3 .135
12 Catalog-modifyingstatements.136
12.1 .136
12.2 .137
12.3 .138
12.4 .139
12.5 .142
12.6 .143
12.7 .145
12.8 .146
13 Data-modifyingstatements.147
13.1 .147
13.2 .149
13.3 .154
13.4 .158
13.5 .160
13.6 .162
14 Query statements.163
14.1 .163
14.2 .164
14.3 and.168
14.4 .170
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14.5 .173
14.6 .174
14.7 .175
14.8 .177
14.9 .180
14.10 .182
14.11 .185
14.12 .190
15 Procedure calling.199
15.1 and.199
15.2 .201
15.3 .203
16 Common elements.205
16.1 .205
16.2 .206
16.3 .208
16.4 .213
16.5 .219
16.6 .222
16.7 .226
16.8 .236
16.9 .238
16.10 .239
16.11 .240
16.12 .242
16.13 .247
16.14 .248
16.15 .250
16.16 .252
16.17 .253
16.18 .256
16.19 .257
17 Object references.258
17.1 and.258
17.2 and.261
17.3 and.263
17.4 and.264
17.5 and.266
17.6 .267
17.7 .269
17.8 .271
18 Type elements.272
18.1 .272
18.2 .277
18.3 .281
18.4 and.289
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18.5 .290
18.6 .291
18.7 .292
18.8 .293
18.9 .294
18.10 .318
19 Predicates.319
19.1 .319
19.2 .320
19.3 .321
19.4 .326
19.5 .327
19.6 .328
19.7 .329
19.8 .330
19.9 .331
19.10 .332
19.11 .334
19.12 .335
19.13 .336
20 Valueexpressionsandspecifications.337
20.1 .337
20.2 .339
20.3 .340
20.4 .342
20.5 .343
20.6 .344
20.7 .346
20.8 .349
20.9 .363
20.10 .369
20.11 .370
20.12 .372
20.13 .375
20.14 .377
20.15 .378
20.16 .379
20.17 .381
20.18 .383
20.19 .385
20.20 .386
20.21 .388
20.22 .390
20.23 .397
20.24 .400
20.25 .405
20.26 .407
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20.27 .408
20.28 .414
20.29 .418
21 Lexical elements.422
21.1 Namesandvariables.422
21.2 .425
21.3 ,,and.438
21.4 .448
22 Additionalcommonrules.452
22.1 Annotationofa.452
22.2 Machineryforgraphpatternmatching.455
22.3 Evaluationofa.460
22.4 Evaluationofaselective.465
22.5 Satisfactionofabyalabelset.469
22.6 Applicationofbindingstoevaluateanexpression.471
22.7 Evaluationofanexpressiononagroupvariable.475
22.8 Applicationofbindingstogeneratearecord.476
22.9 Resolutionofafromastartdirectory.478
22.10 Store assignment.479
22.11 Determinationofidenticalvalues.485
22.12 Determinationofdistinctvalues.487
22.13 Equality operations.489
22.14 Orderingoperations.490
22.15 Groupingoperations.491
22.16 Determinationofcollation.492
22.17 Graph-typespecificcombinationofpropertyvaluetypes.493
22.18 Generalcombinationofvaluetypes.494
22.19 Staticcombinationofvaluetypes.497
22.20 Determinationofvaluetypeprecedence.500
23 GQLSTATUSanddiagnosticrecords.505
23.1 GQLSTATUS.505
23.2 Diagnostic records.510
24 Conformance.513
24.1 Introductiontoconformance.513
24.2 Minimum conformance.513
24.3 Conformancetofeatures.513
24.4 RequirementsforGQL-programs.515
24.4.1 IntroductiontorequirementsforGQL-programs.515
24.4.2 ClaimsofconformanceforGQL-programs.515
24.5 RequirementsforGQL-implementations.516
24.5.1 IntroductiontorequirementsforGQL-implementations.516
24.5.2 ClaimsofconformanceforGQL-implementations.516
24.5.3 Extensionsandoptions.516
24.6 GQLFlagger.516
24.7 Impliedfeaturerelationships.517
AnnexA(informative) GQLconformancesummary.522
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AnnexB(informative) Implementation-defined elements.555
AnnexC(informative) Implementation-dependent elements.574
AnnexD(informative) GQLoptionalfeaturetaxonomy.577
AnnexE(informative) MaintenanceandinterpretationofGQL.587
Bibliography.588
Index.589
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Tables
Table Page
1 Validoperatorsinvolvingvaluesoftemporaltypes.92
2 SymbolsusedinBNF.97
3 Conversionofsimplifiedsyntaxdelimiterstodefaultedgedelimiters.244
4 Validcombinationsofsourceandtargetandtypes.350
5 TruthtablefortheANDBooleanoperator.387
6 TruthtablefortheORBooleanoperator.387
7 TruthtablefortheISBooleanoperator.387
8 GQLSTATUSclassandsubclasscodes.505
9 Operationcodes.510
10 Impliedfeaturerelationships.517
D.1 Featuretaxonomyforoptionalfeatures.577
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Figures
Figure Page
1 ComponentsofaGQL-environment.21
2 ComponentsofaGQL-catalog.25
3 Majorclassesofdatatypes.61
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ISO/IEC39075:2024(en)
Foreword
ISO(theInternationalOrganizationforStandardization)andIEC(theInternationalElectrotechnical
Commission)formthespecializedsystemforworldwidestandardization.Nationalbodiesthatare
membersofISOorIECparticipateinthedevelopmentofInternationalStandardsthroughtechnical
committeesestablishedbytherespectiveorganizationtodealwithparticularfieldsoftechnicalactivity.
ISOandIECtechnicalcommitteescollaborateinfieldsofmutualinterest.Otherinternationalorganizations,
governmentalandnon-governmental,inliaisonwithISOandIEC,alsotakepartinthework.
Theproceduresusedtodevelopthisdocumentandthoseintendedforitsfurthermaintenanceare
describedintheISO/IECDirectives,Part1.Inparticular,thedifferentapprovalcriterianeededforthe
differenttypesofdocumentshouldbenoted.Thisdocumentwasdraftedinaccordancewiththeeditorial
rulesoftheISO/IECDirectives,Part2(seehttps://www.iso.org/directivesor
https://www.iec.ch/members_experts/refdocs).
ISOandIECdrawattentiontothepossibilitythattheimplementationofthisdocumentmayinvolvethe
useof(a)patent(s).ISOandIECtakenopositionconcerningtheevidence,validityorapplicabilityofany
claimedpatentrightsinrespectthereof.Asofthedateofpublicationofthisdocument,ISOandIEChad
notreceivednoticeof(a)patent(s)whichmayberequiredtoimplementthisdocument.However,
implementersarecautionedthatthismaynotrepresentthelatestinformation,whichmaybeobtained
fromthepatentdatabaseavailableathttps://www.iso.org/patentsandhttps://pat-
ents.iec.ch.ISOandIECshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.
Anytradenameusedinthisdocumentisinformationgivenfortheconvenienceofusersanddoesnot
constituteanendorsement.
Foranexplanationofthevoluntarynatureofstandards,themeaningofISOspecifictermsandexpressions
relatedtoconformityassessment,aswellasinformationaboutISO’sadherencetotheWorldTrade
Organization(WTO)principlesintheTechnicalBarrierstoTrade(TBT)see
https://www.iso.org/iso/foreword.html.IntheIEC,seehttps://www.iec.ch/under-
standing-standards.
ThisdocumentwaspreparedbyJointTechnicalCommitteeISO/IECJTC1,Informationtechnology,Sub-
committeeSC32,Datamanagementandinterchange.
Anyfeedbackorquestionsonthisdocumentshouldbedirectedtotheuser’snationalstandardsbody.
https://www.iso.org/members.htmlandhttps://www.iec.ch/national-committees.
©ISO/IEC2024–Allrightsreserved
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ISO/IEC39075:2024(en)
Introduction
ThisdocumentdefinesGQL,adatabaselanguageformodelingstructureddataasagraph,andforstoring,
querying,andmodifyingthatdatainagraphdatabaseorothergraphstore.Therearetwomajorgraph
datamodelsincurrentuse:theResourceDescriptionFramework(RDF)modelandthePropertyGraph
model.TheRDFmodelhasbeenstandardizedbyW3Cinanumberofspecifications.GQLaddressesthe
PropertyGraphmodel.
Propertygraphsorganizedataasentitiescallednodes(or,alternatively,vertices)andedges(or,altern-
atively,relationships).Eachgraphelement(anodeoranedge)canhaveassociatedlabelsandproperties.
Theflexibilityandintuitivenessofthedatamodelanditsemphasisoninterconnectionsbetweengraph
elementsmakepropertygraphssuitableforstoringcomplexknowledgeandforanalyticaltaskssuchas
entityresolution,frauddetection,cybersecurity,andforecasting.
GQLisdeclarativeandtransactional,takinginspirationfromSQLandfromleadingindependently-
developedpropertygraphlanguages.Propertygraphsselectdataprimarilythroughpathpattern
matching.Definingpathpatternsearchesinagraphisoftensimplerormoreflexiblethandefiningthe
equivalentjoinsinSQL.Theflexibledatamodel,theavailabilityofpathpatternmatching,andtheefficiency
oftraversingedgescomparedtojoiningtableshaveledtoincreasinginterestinpropertygraphdatabases.
Variousgraphdatamodelshavebeenaroundformanydecades,butitisonlysincetheearly21stcentury
thatthedemandhasdriventheriseofcommercialgraphdatabaseandgraphanalyticalsystemsfor
propertygraphs.
GQLprovidesastandardyetflexiblecommonlanguageforthisgrowingmarket.GQLsupportsthesame
graphpatternmatchingsyntaxasSQLPropertyGraphQueries,ISO/IEC9075-16,Informationtechnology
—DatabaselanguagesSQL—Part16:PropertyGraphQueries(SQL/PGQ).WhileSQL/PGQprovidesthe
propertygraphdatamodelandgraphpatternmatchingontopofarelationalSQLdatabase,GQLis
intendedforpurepropertygraphsthatprovidegraphdatamanagementindependentfromSQL.
©ISO/IEC2024–Allrightsreserved
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International Standard
Informationtechnology—Databaselanguages—GQL
1 Scope
Thisdocumentdefinesdatastructuresandbasicoperationsonpropertygraphs.Itprovidescapabilities
forcreating,accessing,querying,maintaining,andcontrollingpropertygraphsandthedatatheycomprise.
Thisdocumentspecifiesthesyntaxandsemanticsofadatamanagementlanguageforspecifyingand
modifyingthestructureofpropertygraphsandcollectionsthereof.Thisdocumentprovidesavehiclefor
portabilityofdatadefinitionsandmanipulationamongGQL-implementations.
Implementationsofthisdocumentcanexistinenvironmentsthatalsosupportapplicationprogramming
languages,end-userqueryfacilities,andvarioustoolsfordatabasedesign,dataadministration,and
performanceoptimization.
©ISO/IEC2024–Allrightsreserved
ISO/IEC39075:2024(en)
2 Normativereferences
Thefollowingdocumentsarereferredtointhetextinsuchawaythatsomeoralloftheircontentconsti-
tutesrequirementsofthisdocument.Fordatedreferences,onlytheeditioncitedapplies.Forundated
references,thelatesteditionofthereferenceddocument(includinganyamendments)applies.
ISO8601-1:2019,Dateandtime—Representationsforinformationinterchange—Part1:Basicrules
ISO8601-2:2019,Dateandtime—Representationsforinformationinterchange—Part2:Extensions
ISO/IEC9075-2:2023,Informationtechnology—Databaselanguages—SQL—Part2:Foundation
(SQL/Foundation)
ISO/IEC14651:2020,Informationtechnology—Internationalstringorderingandcomparison—Method
forcomparingcharacterstringsanddescriptionofthecommontemplatetailorableordering
IEEEStd754:2019,IEEEStandardforFloating-PointArithmetic
InternetEngineeringTaskForce(IETF)RFC3986,UniformResourceIdentifier(URI):GenericSyntax.
Editedby:Berners-Lee,T.,Fielding,R.,Masinter,L.January2005
Availableat:https://www.ietf.org/rfc/rfc3986.txt
Kuhn,Markus.CoordinatedUniversalTimewithSmoothedLeapSeconds(UTC-SLS)[online].University
ofCambridge:IETF,January2006.Availableathttps://tools.ietf.org/html/-
draft-kuhn-leapsecond-00
TheUnicodeConsortium.TheUnicodeStandard(InformationaboutthelatestversionoftheUnicode
standardcanbefoundbyusingthe“LatestVersion
...