ISO/IEC 9075-16:2023

Information technology - Database languages SQL - Part 16: Property Graph Queries (SQL/PGQ)

Technologies de l'information — Langages de base de données — SQL — Partie 16: Titre manque

General Information

• Status: Published
• Publication Date: 31-May-2023
• ICS: 35.060 - Languages used in information technology
• Technical Committee: ISO/IEC JTC 1/SC 32 - Data management and interchange
• Drafting Committee: ISO/IEC JTC 1/SC 32/WG 3 - Database language
• Current Stage: 9092 - International Standard to be revised
• Start Date: 22-Jun-2025
• Completion Date: 30-Oct-2025

Overview

ISO/IEC 9075-16:2023 - commonly referred to as SQL/PGQ (Property Graph Queries) - is the ISO standard that extends the SQL family to support querying and manipulating property graph data. Published as the first edition in June 2023, this part of the ISO/IEC 9075 series defines syntax, semantics, predicates, functions, schema and access-control elements for representing and querying property graphs inside SQL environments.

Key topics and technical requirements

The standard specifies a comprehensive set of language elements and behaviors for graph querying with SQL. Major technical topics include:

• Graph pattern matching and matching modes, including path patterns, path modes and selective path search mechanisms.
• Query expressions and table/graph references for integrating graph queries with relational query constructs.
• Scalars, predicates and functions specific to graph processing (e.g., property references, path and element functions).
• Schema definition and manipulation for property graphs: property graph definitions, element/edge table descriptors, label and property declarations, and ALTER/DROP semantics.
• Access control: GRANT/REVOKE statements and property-graph-specific privileges.
• Information Schema and Definition Schema views and base tables to expose graph metadata-examples include PG_LABELS, PG_ELEMENT_TABLES, PG_ELEMENT_TABLE_PROPERTIES, PROPERTY_GRAPHS and PG_DEFINED_LABEL_SETS.
• Diagnostics, conformance and status codes, plus annexes covering optional/implementation-defined elements and incompatibilities with prior SQL parts.

The document organizes its rules into formal lexical elements, scalar expressions, predicates, additional common rules (e.g., binding/application of graph results), and conformance requirements.

Practical applications

ISO/IEC 9075-16:2023 enables:

• Embedding property graph queries directly in SQL-based systems, removing the need for separate graph query languages or ad-hoc integrations.
• Graph analytics (shortest paths, pattern discovery, connected components) combined with relational joins and aggregates in a single SQL environment.
• Consistent metadata exposure across database platforms through the standardized Information Schema views for graph objects.
• Enterprise adoption of knowledge graphs, social/network analysis, fraud detection, recommendation systems and semantic data stores where graph relationships are first-class.

Who should use this standard

• Database vendors implementing graph features in SQL engines.
• Data architects and engineers designing hybrid relational–graph solutions.
• Application developers who need standardized graph query capabilities inside SQL.
• Analysts and researchers leveraging graph-structured data with SQL toolchains.
• Standards and compliance teams ensuring portability and conformance for graph-enabled database products.

Related standards

• Part of the ISO/IEC 9075 (SQL) family - SQL/PGQ complements the core SQL standard and aligns graph querying semantics with established SQL syntax and conformance rules.

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 9075-16
First edition
2023-06
Information technology — Database
languages SQL —
Part 16:
Property Graph Queries (SQL/PGQ)
Reference number
© ISO/IEC 2023
© ISO/IEC 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
© ISO/IEC 2023 – All rights reserved

ISO/IEC9075-16:2023(E)
Contents Page
Foreword.viii
Introduction.x
1 Scope.1
2 Normativereferences.2
3 Termsanddefinitions.3
4 Concepts.8
4.1 Notationsandconventions.8
4.1.1 Notations.8
4.2 Columns,fields,andattributes.8
4.3 SQL-statements.8
4.3.1 SQL-statementsclassifiedbyfunction.8
4.3.1.1 SQL-schemastatements.8
4.4 Basicsecuritymodel.8
4.4.1 Privileges.9
4.5 SQL-propertygraphs.9
4.5.1 IntroductiontoSQL-propertygraphs.9
4.5.2 Purepropertygraph.9
4.5.3 Tabularpropertygraph.11
4.6 Operationsinvolvingpropertygraphs.12
4.7 Graphpatternmatching.13
4.7.1 Summaryofgraphpatternmatching.13
4.7.2 Paths.13
4.7.3 Pathpatterns.14
4.7.4 Graphpatternvariables.15
4.7.5 Referencestographpatternvariables.16
4.7.6 Pathpatternmatching.17
4.7.7 Path modes.18
4.7.8 Selectivepathsearchprefixes.19
4.7.9 Matchmodes.19
5 Lexicalelements.20
5.1 .20
5.2 and.21
5.3 Namesandidentifiers.24
6 Scalarexpressions.26
6.1 .26
6.2 .28
6.3 .30
6.4 .32
©ISO/IEC2023–Allrightsreserved iii

ISO/IEC9075-16:2023(E)
6.5 .33
6.6 .35
6.7 .36
6.8 .37
6.9 .38
6.10 .39
7 Queryexpressions.40
7.1 .40
7.2 .50
8 Predicates.51
8.1 .51
8.2 .52
8.3 .53
8.4 .54
8.5 .56
8.6 .57
8.7 .58
8.8 .60
9 Additionalcommonrules.61
9.1 Potentialsourcesofnon-determinism.61
9.2 Contextualinferenceofasetoflabels.62
9.3 Expansionofan.65
9.4 Satisfactionofabyadefinedlabelset.67
9.5 Convertingatabularpropertygraphtoapurepropertygraph.69
9.6 Machineryforgraphpatternmatching.72
9.7 Evaluationofa.77
9.8 Evaluationofaselective.82
9.9 Applyingbindingstoevaluateanexpression.86
9.10 Applyingbindingstoevaluateasubexpressionofanaggregate.89
9.11 Applyingbindingstogeneratearow.91
9.12 Creationofanelementtabledescriptor.94
9.13 Creationofavertextabledescriptor.98
9.14 Creationofanedgetabledescriptor.99
9.15 Consistencycheckofatabularpropertygraphdescriptor.102
9.16 Derivingapurepropertygraphdescriptorfromatabularpropertygraphdescriptor.104
10 Additionalcommonelements.106
10.1 .106
10.2 .108
10.3 .109
10.4 .110
10.5 .116
10.6 .120
10.7 .129
10.8 .131
10.9 .133
10.10 .138
iv ©ISO/IEC2023–Allrightsreserved

ISO/IEC9075-16:2023(E)
10.11 .140
11 Schemadefinitionandmanipulation.141
11.1 .141
11.2 .142
11.3 .143
11.4 .144
11.5 .145
11.6 .146
11.7 .147
11.8 .148
11.9 .149
11.10 .150
11.11 .151
11.12 .152
11.13 .153
11.14 .154
11.15 .155
11.16 .156
11.17 .157
11.18 .158
11.19 .159
11.20 .164
11.21 .165
11.22 .167
11.23 .170
11.24 .171
11.25 .174
11.26 .176
11.27 .180
12 Accesscontrol.182
12.1 .182
12.2 .183
12.3 .184
13 SQL-clientmodules.187
13.1 .187
13.2 .188
14 Diagnosticsmanagement.189
14.1 .189
15 InformationSchema.191
15.1 InformationSchemadigitalartifact.191
15.2 PG_DEFINED_LABEL_SETSview.191
15.3 PG_DEFINED_LABEL_SET_LABELS view.192
15.4 PG_EDGE_DEFINED_LABEL_SETS view.193
15.5 PG_EDGE_TABLE_COMPONENTSview.194
15.6 PG_EDGE_TRIPLETS view.195
15.7 PG_ELEMENT_TABLE_KEY_COLUMNSview.196
©ISO/IEC2023–Allrightsreserved v

ISO/IEC9075-16:2023(E)
15.8 PG_ELEMENT_TABLE_LABELSview.197
15.9 PG_ELEMENT_TABLE_PROPERTIESview.198
15.10 PG_ELEMENT_TABLES view.199
15.11 PG_LABEL_PROPERTIESview.200
15.12 PG_LABELSview.201
15.13 PG_PROPERTY_DATA_TYPES view.202
15.14 PG_PROPERTY_GRAPH_PRIVILEGESview.203
15.15 PG_VERTEX_DEFINED_LABEL_SETS view.204
15.16 PROPERTY_GRAPHS view.205
16 DefinitionSchema.206
16.1 DefinitionSchemadigitalartifact.206
16.2 DATA_TYPE_DESCRIPTORbasetable.206
16.3 TABLESbasetable.207
16.4 PG_DEFINED_LABEL_SETSbasetable.208
16.5 PG_DEFINED_LABEL_SET_LABELSbasetable.209
16.6 PG_EDGE_DEFINED_LABEL_SETSbasetable.210
16.7 PG_EDGE_TABLE_COMPONENTSbasetable.212
16.8 PG_EDGE_TRIPLETSbasetable.214
16.9 PG_ELEMENT_TABLE_KEY_COLUMNSbasetable.216
16.10 PG_ELEMENT_TABLE_LABELSbasetable.217
16.11 PG_ELEMENT_TABLE_PROPERTIESbasetable.218
16.12 PG_ELEMENT_TABLESbasetable.219
16.13 PG_LABEL_PROPERTIESbasetable.221
16.14 PG_LABELSbasetable.222
16.15 PG_PROPERTY_DATA_TYPESbasetable.223
16.16 PG_PROPERTY_GRAPH_PRIVILEGESbasetable.225
16.17 PG_VERTEX_DEFINED_LABEL_SETSbasetable.227
16.18 PROPERTY_GRAPHSbasetable.228
17 Statuscodes.229
17.1 SQLSTATE.229
18 Conformance.230
18.1 ClaimsofconformancetoSQL/PGQ.230
18.2 AdditionalconformancerequirementsforSQL/PGQ.230
18.3 ImpliedfeaturerelationshipsofSQL/PGQ.230
AnnexA(informative) SQLconformancesummary.234
AnnexB(informative) Implementation-defined elements.249
AnnexC(informative) Implementation-dependent elements.251
AnnexD(informative) SQLoptionalfeaturetaxonomy.254
AnnexE(informative) Deprecatedfeatures.259
AnnexF(informative) IncompatibilitieswithISO/IEC9075:2016.260
AnnexG(informative) DefectReportsnotaddressedinthiseditionofthisdocument.261
Index.262
vi ©ISO/IEC2023–Allrightsreserved

ISO/IEC9075-16:2023(E)
Tables
Table Page
1 Conversionofsimplifiedsyntaxdelimiterstodefaultedgedelimiters.135
2 Datatypesofs.189
3 SQL-statementcodes.190
4 SQLSTATEclassandsubclasscodes.229
5 ImpliedfeaturerelationshipsofSQL/PGQ.230
A.1 FeaturedefinitionsoutsideofConformanceRules.234
D.1 Featuretaxonomyforoptionalfeatures.254
©ISO/IEC2023–Allrightsreserved vii

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical activity.
ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of document should be noted. This document was drafted in accordance with the editorial
rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or
www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC have
not received notice of (a) patent(s) which may be required to implement this document. However,
implementers are cautioned that this may not represent the latest information, which may be obtained
from the patent database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall
not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the World
Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 32, Data management and interchange.
This first edition of ISO/IEC 9075-16 is designed to be used in conjunction with the following editions of
other parts of the ISO/IEC 9075 series, all published in 2023:
— ISO/IEC 9075-1, sixth edition;
— ISO/IEC 9075-2, sixth edition;
— ISO/IEC 9075-3, sixth edition;
— ISO/IEC 9075-4, seventh edition;
— ISO/IEC 9075-9, fifth edition;
— ISO/IEC 9075-10, fifth edition;
— ISO/IEC 9075-11, fifth edition;
viii © ISO/IEC 2023 – All rights reserved

— ISO/IEC 9075-13, fifth edition;
— ISO/IEC 9075-14, sixth edition;
— ISO/IEC 9075-15, second edition.
A list of all parts in the ISO/IEC 9075 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html and www.iec.ch/national-
committees.
© ISO/IEC 2023 – All rights reserved ix

ISO/IEC9075-16:2023(E)
Introduction
Theorganizationofthisdocumentisasfollows:
1) Clause1,“Scope”,specifiesthescopeofthisdocument.
2) Clause2,“Normativereferences”,identifiesadditionalstandardsthat,throughreferenceinthis
document,constituteprovisionsofthisdocument.
3) Clause3,“Termsanddefinitions”,definesthetermsanddefinitionsusedinthisdocument.
4) Clause4,“Concepts”,presentsconceptsusedinthedefinitionofpropertygraphqueries.
5) Clause5,“Lexicalelements”,definesanumberoflexicalelementsusedinthedefinitionofproperty
graphqueries.
6) Clause6,“Scalarexpressions”,definesanumberofscalarexpressionsusedinthedefinitionof
propertygraphqueries.
7) Clause7,“Queryexpressions”,definestheelementsofthelanguagethatproducerowsandtables
ofdataasusedinpropertygraphqueries.
8) Clause8,“Predicates”,definesthepredicatesofthelanguage.
9) Clause9,“Additionalcommonrules”,specifiesadditionalrulesforimplicitorexplicitinvocation
fromotherplacesinthisdocument.
10) Clause10,“Additionalcommonelements”,definesadditionalcommonelementsusedinthedefinition
ofpropertygraphqueries.
11) Clause11,“Schemadefinitionandmanipulation”,definestheschemadefinitionandmanipulation
statementsassociatedwiththedefinitionofpropertygraphqueries.
12) Clause12,“Accesscontrol”,definesfacilitiesforcontrollingaccesstoSQL-data.
13) Clause13,“SQL-clientmodules”,definesthefacilitiesforusingpropertygraphqueries.
14) Clause14,“Diagnosticsmanagement”,definesthediagnosticsmanagementfacilities.
15) Clause15,“InformationSchema”,definesviewedtablesthatcontainschemainformation.
16) Clause16,“DefinitionSchema”,definesbasetablesonwhichtheviewedtablescontainingschema
informationdepend.
17) Clause17,“Statuscodes”,definesSQLSTATEvaluesrelatedtopropertygraphqueries.
18) Clause18,“Conformance”,definesthecriteriaforconformancetothisdocument.
19) AnnexA,“SQLconformancesummary”,isaninformativeAnnex.Itsummarizestheconformance
requirementsoftheSQLlanguage.
20) AnnexB,“Implementation-definedelements”,isaninformativeAnnex.Itliststhosefeaturesfor
whichthebodyofthisdocumentstatesthatthesyntax,themeaning,thereturnedresults,theeffect
onSQL-dataand/orschemas,orotheraspectispartlyorwhollyimplementation-defined.
21) AnnexC,“Implementation-dependentelements”,isaninformativeAnnex.Itliststhosefeaturesfor
whichthebodyofthisdocumentstatesthatthesyntax,themeaning,thereturnedresults,theeffect
onSQL-dataand/orschemas,orotheraspectispartlyorwhollyimplementation-dependent.
x ©ISO/IEC2023–Allrightsreserved

ISO/IEC9075-16:2023(E)
22) AnnexD,“SQLoptionalfeaturetaxonomy”,isaninformativeAnnex.ItidentifiesfeaturesoftheSQL
languagespecifiedinthisdocumentbyanidentifierandashortdescriptivename.Thistaxonomy
isusedtospecifyconformance.
23) AnnexE,“Deprecatedfeatures”,isaninformativeAnnex.Itlistsfeaturesthattheresponsible
TechnicalCommitteeintendsnottoincludeinafutureeditionofthisdocument.
24) AnnexF,“IncompatibilitieswithISO/IEC9075:2016”,isaninformativeAnnex.Itlistsincompatib-
ilitieswiththepreviouseditionofthisdocument.
25) AnnexG,“DefectReportsnotaddressedinthiseditionofthisdocument”,isaninformativeAnnex.
ItdescribestheDefectReportsthatwereknownatthetimeofpublicationofthisdocument.Each
oftheseproblemsisaproblemcarriedforwardfromthepreviouseditionoftheISO/IEC9075
series.Nonewproblemshavebeencreatedinthedraftingofthiseditionofthisdocument.
Inthetextofthisdocument,inClause5,“Lexicalelements”,throughClause18,“Conformance”,Subclauses
beginnewpages.Anyresultingblankspaceisnotsignificant.
©ISO/IEC2023–Allrightsreserved xi

INTERNATIONAL STANDARD ISO/IEC 9075-16:2023(E)
Informationtechnology—DatabaselanguageSQL—
Part16:
PropertyGraphQueries(SQL/PGQ)
1 Scope
ThisdocumentdefineswaysfortheSQLlanguagetorepresentpropertygraphsandtointeractwiththem.
©ISO/IEC2023–Allrightsreserved 1

ISO/IEC9075-16:2023(E)
2 Normativereferences
Thefollowingdocumentsarereferredtointhetextinsuchawaythatsomeoralloftheircontentconsti-
tutesrequirementsofthisdocument.Fordatedreferences,onlytheeditioncitedapplies.Forundated
references,thelatesteditionofthereferenceddocument(includinganyamendments)applies.
ISO/IEC9075-1,Informationtechnology—Databaselanguages—SQL—Part1:Framework
(SQL/Framework)
ISO/IEC9075-2,Informationtechnology—Databaselanguages—SQL—Part2:Foundation
(SQL/Foundation)
ISO/IEC9075-4,Informationtechnology—Databaselanguages—SQL—Part4:PersistentStored
Modules(SQL/PSM)
ISO/IEC9075-11,Informationtechnology—Databaselanguages—SQL—Part11:Informationand
DefinitionSchemas(SQL/Schemata)
2 ©ISO/IEC2023–Allrightsreserved

ISO/IEC9075-16:2023(E)
3 Termsanddefinitions
Forthepurposesofthisdocument,thetermsanddefinitionsgiveninISO/IEC9075-1,ISO/IEC9075-2,
andthefollowingapply.
ISOandIECmaintainterminologicaldatabasesforuseinstandardizationatthefollowingaddresses:
— ISOOnlinebrowsingplatform:availableathttps://www.iso.org/obp
— IECElectropedia:availableathttps://www.electropedia.org/
3.1
destinationvertex
vertex(3.37)thatisdistinguishedasthedestinationofadirectededge(3.4)
3.2
destinationvertextable
tablethatcontainsdatarepresentingthedestinationvertices(3.1)ofadirectededge(3.4)
3.3
definedlabelset
distinguishedsetoflabels
Note1toentry:Subclause4.5.2,“Purepropertygraph”,specifiessixkindsofdefinedlabelsets:vertex
definedlabelset,edgedefinedlabelset,edgetripletdefinedlabelset,sourcevertexdefinedlabelset,
destinationvertexdefinedlabelset,andendpointvertexdefinedlabelset.
3.4
directededge
edge(3.6)thatdistinguishesoneofitsendpoints(3.14)asitssourcevertex(3.30)andoneofitsendpoints
asitsdestinationvertex(3.1)
Note1toentry:Adirectededgeexpressesarelationshipthatisasymmetric.
Note2toentry:Theantonymisundirectededge(3.35).
3.5
directedgraph
graphinwhicheveryedge(3.6)isdirected
Note1toentry:Theantonymisundirectedgraph(3.36).
3.6
edge
relationship
connectionbetweentwovertices(3.37)
Note1toentry:Bothterms,“edge”and“relationship”,areusedintherealworldtodenotethesame
concept.Withoutjudgementorprejudice,thisdocumentusesonlytheterm“edge”.InBNFproductions,
whereverthekeywordEDGEisallowed,thekeywordRELATIONSHIPcanequallywellbeusedinstead.
3.7
edgepattern
pathpattern(3.24)thatmatchesasingleedge(3.6)
©ISO/IEC2023–Allrightsreserved 3

ISO/IEC9075-16:2023(E)
3 Termsanddefinitions
3.8
edgetable
tablethatcontainsdatarepresentingedges(3.6)
3.9
edgetablealias
identifierthatuniquelyidentifiesanedgetable(3.8)withinanSQL-propertygraph(3.32)
3.10
edgevariable
elementvariable(3.13)thatisdeclaredinanedgepattern(3.7)orastheseconditeratorvariable(3.18)
in
Note1toentry:Anedgevariablemaybeboundtoalistofedges(3.6).
3.11
elementpattern
edgepattern(3.7)orvertexpattern(3.38)
3.12
elementtable
edgetable(3.8)orvertextable(3.39)
3.13
elementvariable
variablethatmaybeboundtoalistofgraphelements(3.15)
Note1toentry:Anelementvariableiseitheraprimaryvariable(3.27)oraniteratorvariable(3.18).
Note2toentry:Anelementvariableiseitheravertexvariable(3.41)oranedgevariable(3.10).
3.14
endpoint
oneofthetwovertices(3.37)connectedbyanedge(3.6)
Note1toentry:Bothendpointsofanedgemaybethesamevertex.
3.15
graphelement
vertex(3.37)oredge(3.6)
3.16
graphpattern
setofoneormorepathpatterns(3.24)
3.17
graphpatternvariable
pathvariable(3.25),subpathvariable(3.34),orelementvariable(3.13)
3.18
iteratorvariable
elementvariable(3.13)thatisdeclaredin
3.19
label
identifierassociatedwithavertex(3.37)oredge(3.6)
4 ©ISO/IEC2023–Allrightsreserved

ISO/IEC9075-16:2023(E)
3 Termsanddefinitions
3.20
labelexpression
expressioncomposedfromlabel(3.19)namesusingdisjunction,conjunction,andnegation
Note1toentry:Disjunction,conjunction,andnegationaredenotedrespectivelybyaverticalbar“|”,
ampersand“&”andexclamationmark“!”,withparenthesesforgrouping.SeeSubclause10.8,“ expression>”formoredetails.
3.21
mixedgraph
graphthatallowsbothdirectedandundirectededges(3.6)
3.22
multigraph
graphthatallowsmorethanoneedge(3.6)connectingtwovertices(3.37)
3.23
path
sequenceofanoddnumberofgraphelements(3.15)
Note1toentry:Apathalwaysstartsandendswithavertex(3.37)andalternatesbetweenverticesand
edges(3.6),suchthateachedgeresidesinthepathbetweenitsendpoints(3.14).SeeSubclause4.7.2,
“Paths”,forafullerdiscussionofpaths.
Note2toentry:Apathmayconsistofasinglevertex.
Note3toentry:Avertexoranedgemaybecontainedmultipletimesinapath,includingviaself-loops.
3.24
pathpattern
pattern(3.26)thatmatchesapath(3.23)
3.25
pathvariable
graphpatternvariable(3.17)thatmaybeboundtoapathbindingthatismatchedbyapathpattern(3.24)
Note1toentry:Theextractedpathofthepathbindingisapath(3.23).
Note2toentry:ExtractedpathandpathbindingaredefinedinSubclause9.6,“Machineryforgraph
patternmatching”.
3.26
pattern
syntaxforspecifyingrequirementsonthebindingsofvariables
3.27
primaryvariable
elementvariable(3.13)thatisdeclaredinanelementpattern(3.11)
3.28
property
(propertyname,datatype)pair
Note1toentry:Thevalueofapropertyisavalueofitsdatatype.
3.29
propertygraph
datastructureconsistingofzeroormorevertices(3.37)andzeroormoreedges(3.6)
©ISO/IEC2023–Allrightsreserved 5

ISO/IEC9075-16:2023(E)
3 Termsanddefinitions
3.30
sourcevertex
vertex(3.37)thatisdistinguishedasthesourceofadirectededge(3.4)
3.31
sourcevertextable
tablethatcontainsdatarepresentingthesourcevertices(3.30)ofadirectededge(3.4)
3.32
SQL-propertygraph
SQL-schemaobjectthatrepresentsvertices(3.37)andedges(3.6)usingtables
3.33
subpath
path(3.23)fullycontainedinanotherpath
Note1toentry:Asubpathmaybeidenticaltoitscontainingpath.
3.34
subpathvariable
graphpatternvariable(3.17)thatisdeclaredattheheadofa
3.35
undirectededge
edge(3.6)thatdoesnotdistinguishbetweenitsendpoints(3.14)
Note1toentry:Anundirectededgeexpressesarelationshipthatisnecessarilysymmetric.
Note2toentry:Theantonymisdirectededge(3.4).
3.36
undirectedgraph
graphinwhicheveryedge(3.6)isundirected
Note1toentry:Theantonymisdirectedgraph(3.5).
3.37
vertex
node
fundamentalunitofwhichapropertygraph(3.29)isformed
Note1toentry:plural:verticesornodes.
Note2toentry:Bothterms,“vertex”and“node”,areusedintherealworldtodenotethesameconcept.
Withoutjudgementorprejudice,thisdocumentusesonlytheterm“vertex”.InBNFproductions,wherever
thekeywordVERTEXisallowed,thekeywordNODEcanequallywellbeusedinstead.
3.38
vertexpattern
pathpattern(3.24)thatmatchesasinglevertex(3.37)
3.39
vertextable
tablethatcontainsdatarepresentingvertices(3.37)
3.40
vertextablealias
identifierthatuniquelyidentifiesavertextable(3.39)withinanSQL-propertygraph(3.32)
6 ©ISO/IEC2023–Allrightsreserved

ISO/IEC9075-16:2023(E)
3 Termsanddefinitions
3.41
vertexvariable
elementvariable(3.13)thatisdeclaredinavertexpattern(3.38)orasaniteratorvariable(3.18)in rowpervertex>orasthefirstorthirditeratorvariablein
Note1toentry:Avertexvariablemaybeboundtoalistofvertices(3.37).
©ISO/IEC2023–Allrightsreserved 7

ISO/IEC9075-16:2023(E)
4 Concepts
ThisClausemodifiesClause4,“Concepts”,inISO/IEC9075-2.
4.1 Notationsandconventions
ThisSubclausemodifiesSubclause4.1,“Notationsandconventions”,inISO/IEC9075-2.
4.1.1 Notations
ThisSubclausemodifiesSubclause4.1.1,“Notations”,inISO/IEC9075-2.
ThenotationsusedinthisdocumentaredefinedinISO/IEC9075-1.
ThesyntaxdefinedinthisdocumentisavailablefromtheISOwebsiteasa“digitalartifact”.Thesyntax
definedinthisdocumentisavailablefromtheISOwebsiteasa“digitalartifact”.Seehttps://stand-
ards.iso.org/iso-iec/9075/-16/ed-1/en/todownloaddigitalartifactsforthisdocument.To
downloadthesyntaxdefinedinaplain-textformat,selectthefilenamedISO_IEC_9075-
16(E)_PGQ.bnf.txt.TodownloadthesyntaxdefinedinanXMLformat,selectthefilenamed
ISO_IEC_9075-16(E)_PGQ.bnf.xml.
4.2 Columns,fields,andattributes
ThisSubclausemodifiesSubclause4.15,“Columns,fields,andattributes”,inISO/IEC9075-2.
Insertafterthe5thparagraph: Thenullabilitycharacteristicofacolumnofisdefinedby
theSyntaxRulesofSubclause7.1,“”.
4.3 SQL-statements
ThisSubclausemodifiesSubclause4.41,“SQL-statements”,inISO/IEC9075-2.
4.3.1 SQL-statementsclassifiedbyfunction
ThisSubclausemodifiesSubclause4.41.2,“SQL-statementsclassifiedbyfunction”,inISO/IEC9075-2.
4.3.1.1 SQL-schemastatements
ThisSubclausemodifiesSubclause4.41.2.1,“SQL-schemastatements”,inISO/IEC9075-2.
Insertintothe1stparagraph,afterthelastlistitem:
— .
— .
— .
4.4 Basicsecuritymodel
ThisSubclausemodifiesSubclause4.42,“Basicsecuritymodel”,inISO/IEC9075-2.
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4.4 Basicsecuritymodel
4.4.1 Privileges
ThisSubclausemodifiesSubclause4.42.2,“Privileges”,inISO/IEC9075-2.
Insertintothe1stparagraph,afterthelastlistitem:
— AnSQL-propertygraph.
Insertafterthe8thparagraph: AprivilegedescriptorwithanobjectthatisanSQL-propertygraphPG
andanactionofSELECTiscalledapropertygraphprivilegedescriptorandidentifiestheexistenceofa
privilegeonPG.
4.5 SQL-propertygraphs
4.5.1 IntroductiontoSQL-propertygraphs
AnSQL-propertygraphisdescribedbyanSQL-propertygraphdescriptor.Thisdescriptorincludesthe
following.
— Theschema-qualifiednameoftheSQL-propertygraph.
— Apurepropertygraphdescriptordescribingthepurepropertygraph.
— Atabularpropertygraphdescriptordescribingthetabularpropertygraph.
ThedatamakingupanSQL-propertygraphisthedataexposedthroughthevertexandedgetablesthat
arepartofthetabularpropertygraph.
4.5.2 Purepropertygraph
Apurepropertygraphisamixedmultigraphandconsistsofthefollowing.
— Asetofvertices.Eachvertexconsistsofthefollowing.
• Anidentifierthatisuniquewithinthepurepropertygraph.
NOTE1—Thevalueofavertexidentifierisimplementation-dependent(UV021)andisnotrequiredtobe
accessible.Thisuniqueidentifierisusedfordefinitionalpurposestoestablishtheidentityofthevertex.
• Asetofzeroormorelabels(alsoknownasavertexdefinedlabelset)thatdeterminesthe
propertiesofthevertex.Alabelhasaname(i.e.,an).
• Zeroormoreproperties.Foreachproperty:
— itsname;
— itsdeclaredtype,whichcanbeanySQLdatatype,
— itsvalue.
— Asetofedges.Eachedgeconsistsofthefollowing.
• Anidentifierthatisuniquewithinthepurepropertygraph.
NOTE2—Thevalueofanedgeidentifierisimplementation-dependent(UV022)andisnotrequiredtobe
accessible.Thisuniqueidentifierisusedfordefinitionalpurposestoestablishtheidentityoftheedge.
• Asetofzeroormorelabels(alsoknownasanedgedefinedlabelset)thatdeterminesthe
propertiesoftheedge.Alabelhasaname(i.e.,an).
• Zeroormoreproperties.Foreachproperty:
— itsname;
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4.5 SQL-propertygraphs
— itsdeclaredtype,whichcanbeanySQLdatatype;
— itsvalue.
• Anindication,whethertheedgeisdirectedorundirected.
Case:
— Iftheedgeisdirected,thenanorderedpairofvertices,asfollows.
• Asourcevertex.
• Adestinationvertex.
NOTE3—Thedirectionofanedgeisfromitssourcevertextoitsdestinationvertex.
NOTE4—Boththedestinationvertexandthesourcevertexofanedgearepartofthesame
purepropertygraphastheedge.
NOTE5—Thesourcevertexandthedestinationvertexcanbethesamevertex.
— Iftheedgeisundirected,thenanunorderedpairofvertices,theendpointsofthe
undirectededge.
NOTE6—Thepurepropertygraphmodelsupportsundirectededges,whilethetabulargraphmodel
doesnot.AnSQL-implementationcanprovideimplementation-definedmeanstopopulateanundirected
ormixedgraph.Thisdocumentspecifiesquerysyntax(inSubclause10.6,“ expression>”)andsemantics(theGeneralRulesregardinginSubclause9.7,“Evaluation
ofa”)toqueryundirectededges,ifanSQL-implementationsupports
undirectededges.
NOTE7—Thetwoendpointsofanundirectededgecanbethesamevertex.
NOTE8—Thecaseofadirectededgewhosesourceanddestinationvertexarethesameisdistinguished
fromanundirectededgewhoseendpointsarethesame.
Apurepropertygraphisdescribedbyapurepropertygraphdescriptor.Thisdescriptorincludesthefol-
lowing.
— Asetofzeroormorelabels.Eachlabelconsistsofthefollowing.
• Anthatisuniquewithinthepurepropertygraphdescriptor.
NOTE9—Theofalabelisalsoknownasthenameofthelabel.
• Asetofzeroormoreproperties.Eachpropertyconsistsofthefollowing.
— Itsname,whichisanthatisuniquewithinthelabel.
— Itsdeclaredtype.
— Apossiblyemptysetofvertexdefinedlabelsets.
— Apossiblyemptysetofedgedefinedlabelsets.
• Foreachedgedefinedlabelset,anindicationwhetheredgesthathavethatedgedefinedlabel
setarealwaysdirected,alwaysundirected,orpossiblydirectedorundirected.
— Apossiblyemptysetofedgetriplets.Anedgetripletconsistsofthefollowing.
• Anedgetripletdefinedlabelset,whichisasubsetofanedgedefinedlabelset.
• Anindicationwhethertheedgetripletdescribesdirectededgesorundirectededges.
Case:
— Iftheedgetripletdescribesdirectededges,then:
• asourcevertexdefinedlabelset,whichisasubsetofavertexdefinedlabelset;
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4.5 SQL-propertygraphs
• adestinationdefinedvertexlabelset,whichisasubsetofavertexdefinedlabelset.
— Iftheedgetripletdescribesundirectededges,then:
• apairofendpointvertexdefinedlabelsets,eachofwhichisasubsetofavertex
definedlabelset.
4.5.3 Tabularpropertygraph
Atabularpropertygraphcomprisesthefollowing.
— Zeroormorevertextables.
— Zeroormoreedgetables.
AtabularpropertygraphTPGisdescribedbyatabularpropertygraphdescriptor.Thisdescriptorincludes
thefollowing.
— Thedescriptorsofzeroormorevertextables.Eachvertextabledescriptorincludesthefollowing.
• Ifthevertextableisbasedonapersistentbasetableorviewedtable,thentheschema-qualified
nameofthattableV;otherwise,adefiningthevertextable.
• ThevertextablealiasthatidentifiesVasavertextablewithintheSQL-propertygraphthat
containsTPG.
• AlistofcolumnsthatuniquelyidentifyarowinV.
• Oneormorelabels.Eachlabelconsistsofthefollowing.
— An.
— Asetofzeroormoreproperties.Eachpropertyconsistsofthefollowing.
• Aname,whichisanthatisuniquewithinthelabel.
• Adeclaredtype.
• Aassociatedwiththeproperty.
NOTE10—Whileapurepropertygraphallowsavertextohavezerolabels,inatabularpropertygrapha
vertexhasatleastonelabel.
— Thedescriptorsofzeroormoreedgetables.Eachedgetabledescriptorincludesthefollowing.
• Iftheedgetableisbasedonapersistentbasetableorviewedtable,thentheschema-qualified
nameofthattableE;otherwise,adefiningtheedgetable.
• TheedgetablealiasthatidentifiesEasanedgetablewithintheSQL-propertygraphthat
containsTPG.
• AlistofcolumnsthatuniquelyidentifyarowinE.
• Oneormorelabels.Eachlabelconsistsofthefollowing.
— An.
— Asetofzeroormoreproperties.Eachpropertyconsistsofthefollowing.
• Aname,whichisanthatisuniquewithinthelabel.
• Adeclaredtype.
• Aassociatedwiththeproperty.
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4.5 SQL-propertygraphs
NOTE11—Whileapurepropertygraphallowsanedgetohavezerolabels,inatabularpropertygraphan
edgehasatleastonelabel.
• Thenameofthesourcevertextable.
• Theedgesourcekey:oneormorecolumns(oftheedgetable)referencingoneormorerows
inthesourcevertextable.
• Thesourcevertexkey:oneormorecolumns(ofthesourcevertextable)thatcorrespondto
theedgesourcekey
• Thenameofthedestinationvertextable.
• Theedgedestinationkey:oneormorecolumns(oftheedgetable)referencingoneormore
rowsinthedestinationvertextable.
• Thedestinationvertexkey:oneormorecolumns(ofthedestinationvertextable)thatcorres-
pondtotheedgedestinationkey.
4.6 Operationsinvolvingpropertygraphs
isakindofthatappliesatoapropertygraphandformats
theresultsasatable.
isapredicatetotestwhetheranedgevariableisboundtoadirectededge.
NOTE12—isspecifiedforuseinmixedgraphs;however,thisdocumentdoesnotprovideameans
tocreateamixedgraph.
isapredicatetotestwhetherthegraphelementboundtoanelementvariablesatisfies
a.
isapairofpredicates,totestwhetheravertexvariableisboundtothe
sourceordestinationoftheedgethatisboundtoanedgevariable.
isapredicatetotestwhetheralistofelementvariablesareboundtopairwise
distinctgraphelements.
isapredicatetotestwhetheralistofelementvariablesareboundtothesamegraph
element.
isapredicatetotestwhetheranelementvariableisboundtoatleastonegraphele-
ment.Optionalsyntaxoftestswhetheraniteratorvariableisboundtothesame
positioninapathbindingasaprimaryvariable.
isapredicatetodetermineifthegraphelementboundtoasingletonelement
variablehasaparticularproperty.
isafunctiontoobtainavaluethatencapsulatestheidentityofagraphelement.
Thedeclaredtypeofisanimplementation-defined(IV120)typethatissuitable
forequalityoperationsandgroupingoperations.Thevaluereturnedbyencapsulates
theidentityofthegraphelementforatleastthedurationoftheinnermostexecutingSQL-statement.
isafunctiontoobtainauniqueimplementation-dependent(UV016)
numberidentifyingthecurrentmatchbeingreturnedby.
isafunctiontoobtainthenameofthepathvariableofthepaththatthe
iteratorvariable(s)arecurrentlyiteratingover.
isafunctiontoobtainthe1-relativesequentialnumberofthe
graphelementinapathbindingthataniteratorvariableispositionedon.
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4.6 Operationsinvolvingpropertygraphs
Awithin-matchaggregateisacontainedinawithoutan
intervening.Awithin-matchaggregatecomputesavaluefromthegroupofgraph
elementsreferencedbyanelementreferencewhosedegreeofreferenceiseffectivelyboundedgroup.
4.7 Graphpatternmatching
4.7.1 Summaryofgraphpatternmatching
Graphpatternmatchingistheprocessofapplyingalistofspecial-purposeregularexpressionscalleda
onapurepropertygraphPGinordertoreturnasetofreducedmatches.Eachreduced
matchisalistofpathbindings;eachpathbindingisafunctionthatmapsthesymbolsinawordofa
regularlanguagetoapathofPG.Theregularlanguageandrelatedconceptssuchaspathbindingand
reducedmatcharespecifiedinSubclause9.6,“Machineryforgraphpatternmatching”,andSubclause10.4,
“”.
Aisalistofs.EachinthelistismatchedtoPGtodetect
apossibly-emptysetofpathbindingsinPGthatcorrespondtothe.
Thecross-productofthesesetsisreducedbynaturaljoinsoverthoseglobalsingletonelementvariables
thatareexposedbyeachandthatareboundtothesamegraphelementinPG.The
remainingtuplesarecalledreducedmatches;thesetofthesereducedmatchesmaybeempty,butcannot
beinfinitebecauseofsyntacticrestrictionstoguardagainstinfinitecycling.
Thebehaviorofthegraphpatternmatch
...