Spanner Graph and ISO standards

The page describes how Spanner Graph supports the ISO international standard query language for graph databases.

Spanner Graph is based on two ISO standards:

The following tables describe the high-level relationship between SQL/PGQ, GQL, and how Spanner Graph supports these standards.

Standard SQL/PGQ GQL Spanner Graph
Query Graph pattern matching capabilities Shares the core Graph Pattern Matching Language (GPML) functionalities with GQL. Shares the core GPML functionalities with SQL/PGQ. Both standards are supported. For more information, see Spanner Graph GQL patterns.
Query Other query language features (for example, LIMIT, ORDER, aggregation) SQL-based. Similar to SQL, but the GQL query features are linearly composable graph query statements. Both standards are supported. For more information, see Spanner Graph GQL query statements and Query syntax in GoogleSQL.
Query Graph and table interoperability Supported. Not supported. Both standards are supported. For more information, see GRAPH_TABLE operator.
Types Data types, functions and expressions in SQL/PGQ and GQL are similar. Data types, functions and expressions in SQL/PGQ and GQL are similar. Supports most data types and expressions in SQL/PGQ and GQL. For more information, see Data types in GoogleSQL,
DML SQL/PGQ inherits DML from SQL. Graph-based DML is supported. Supports SQL table-based DML. For more information, see the GoogleSQL data manipulation language.
Schema Supports using CREATE PROPERTY GRAPH from tables. Supports using CREATE PROPERTY GRAPH with open types and closed types. Supports the SQL/PGQ method. For more information, see the CREATE PROPERTY GRAPH definition.

SQL/PGQ support

Standard SQL/PGQ feature ID Spanner Graph
Query (Graph and table interoperability) Feature G900: GRAPH_TABLE Supported. For more information, see GRAPH_TABLE operator.
Schema Feature G924: Explicit key clause for element tables. This implies a claim of conformance to Feature G920: DDL-based SQL-property graphs. Supported. For more information, see CREATE_PROPERTY_GRAPH statement.
Schema Feature G925: Explicit label and properties clause for element tables. This implies a claim of conformance to Feature G920: DDL-based SQL-property graphs. Supported. For more information, see CREATE_PROPERTY_GRAPH statement.
Query (GPML) Feature G001: Repeatable-elements match mode. Supported. Repeatable elements match mode is the default semantic. Explicit repeatable elements match mode clause syntax is not supported.
Query (GPML) Feature G008: Graph pattern WHERE clause. This implies a claim of conformance to Feature G000: Graph pattern. Supported. For more information, see Graph pattern.
Query (GPML) Feature G034: Path concatenation. Supported. For more information, see see Graph pattern.
Query (GPML) Feature G040: Vertex pattern. Supported. For more information, see Element pattern.
Query (GPML) Feature G042: Basic full edge patterns. Supported. For more information, see Element pattern.
Query (GPML) Feature G070: Label expression: label disjunction. Supported. For more information, see Label expression.
Query (GPML) Feature G073: Label expression: individual label name. Supported. For more information, see Label expression.
Query (GPML) Feature G090: Property reference. Supported.

GQL support

Standard GQL feature ID Spanner Graph
Schema Feature GG02: Graph with a closed graph type. Conformance with at least one of GG20, GG21, GG22, or GG23:
  • Feature GG20: Explicit element type names.
  • Feature GG21: Explicit element type key label sets.
  • Feature GG22: Element type key label set inference.
  • Feature GG22: Element type key label set inference.
  • Feature GG23 Optional element type key label sets.
 Supported. GQL support can be chosen from GG01: Graph with an open type or GG02.
Spanner Graph doesn't support the exact same CREATE_GRAPH_TYPE statement as GQL. However, the CREATE_PROPERTY_GRAPH statement supported by Spanner Graph is closely related to GG02 (with similar support for GG20, GG21, GG22, and GG23).
Lexical structure "A claim of conformance to a specific version of TheUnicode® Standard and the synchronous versions of Unicode Technical Standard #10, Unicode Standard Annex #15, and Unicode Standard Annex #31. The claimed version of The Unicode® Standard shall not be less than 13.0.0." Spanner Graph GQL shares the exact lexical structure with GoogleSQL. For reference to unicode escape values, see Escape sequences for string and bytes literals.
Data types "A claim of conformance to the set of all value types that are supported as the types of property values. At minimum, this set shall include:
  • The character string type specified by STRING or VARCHAR.
  • The boolean type specified by BOOLEAN or BOOL.
  • The signed regular integer type specified by SIGNED INTEGER, INTEGER, or INT.
  • The approximate numeric type specified by FLOAT."
 Supported. For more information, see a full list of data types supported by Spanner Graph GQL.

Additional features

The features listed in the previous sections are the minimal conformance features of the standards. Spanner Graph supports additional features in the ISO standards. To learn more, see Spanner Graph schema overview and GQL overview.