GQL Conformance (ISO/IEC 39075:2024)¶

This document maps Grafeo's GQL implementation against the ISO/IEC 39075:2024 standard, declaring which features are supported, partially supported or not yet implemented.

Grafeo targets minimum conformance plus a broad set of optional features.

A machine-readable version of this compliance matrix is available as gql-dialect.json for tool integration (e.g. GraphGlot). Regenerate it with python scripts/gql-conformance.py dialect.

Minimum Conformance (Section 24.2)¶

Per the standard, minimum conformance requires:

Core Language: Statements¶

Query Statements (Section 14)¶

Data Modification (Section 13)¶

Catalog / DDL (Section 12)¶

Session Management (Section 7)¶

Transaction Management (Section 8)¶

Procedure Calling (Section 15)¶

Composite Queries (Section 14)¶

Graph Patterns (Section 16)¶

Node and Edge Patterns¶

Label Expressions (Section 16.8)¶

Path Modes (Section 16.6)¶

Path Search Prefixes (Section 16.6)¶

Match Modes (Section 16.4)¶

Quantifiers (Section 16.11)¶

Pattern Composition¶

Expressions and Predicates¶

Operators¶

s =~ pattern is a Grafeo extension: ISO GQL has no regular expressions. It has the meaning and the precedence of Cypher's =~: true when the pattern matches the whole string, null when either side is null (see Filtering). The pattern syntax is that of the Rust regex crate: classes, alternation, repetition, anchors and inline flags such as (?i), without look-around or backreferences. The browser (WASM) build uses regex-lite, which has the same syntax but \d, \w and \s match ASCII characters only, (?i) folds ASCII letters only, and Unicode classes such as \p{L} and class set operations (&&, --) are not available. A pattern the query gives (as a string or a parameter) that is not a regular expression is an error that names it. A build with neither the regex nor the regex-lite feature refuses =~ and LIKE with an error that says so.

Predicates (Section 19)¶

Value Expressions (Section 20)¶

Aggregate Functions¶

Optional Features (Annex D)¶

Pattern Features¶

Predicate & Expression Features¶

Function Features¶

Catalog & Graph Features¶

Session & Transaction Features¶

Procedure Features¶

Query Composition Features¶

Value Type Features¶

Lexical Features¶

Miscellaneous Features¶

Three-Valued Logic¶

GQL uses three-valued logic where comparisons involving NULL produce UNKNOWN (not FALSE).

Known Deviations from Standard¶

1. Predicate desugaring: IS DIRECTED, IS LABELED, IS SOURCE/DESTINATION OF are parsed and internally converted to function calls (isDirected(), hasLabel(), etc.) rather than being preserved as first-class predicate AST nodes. Semantics are equivalent.

2. KEEP clause: The standard specifies KEEP <path pattern prefix>, a path mode or search prefix for all path patterns. Grafeo's KEEP takes a match mode for one path pattern (KEEP DIFFERENT EDGES); KEEP <path pattern prefix> is not supported yet (G006, G007).

3. Variable scope validation: The standard defines degree-of-exposure categories (unconditional singleton, conditional singleton, etc.) at parse time. Grafeo defers variable scope validation to execution time.

4. Simplified path patterns: The -/:Label/-> shorthand is desugared to -[:Label]-> at parse time. Both forms are semantically equivalent.

5. Prefix after MATCH: In MATCH TRAIL (...), (...) and MATCH ANY SHORTEST (...), (...) the standard reads the prefix as the first path pattern's. Grafeo applies it to every path pattern of the clause without a prefix of its own; a prefix after a path variable (p = ANY SHORTEST TRAIL (...)) or before a later path pattern holds for that pattern.