Overview
ISO/IEC 9075-15:2023 - SQL/MDA specifies how the SQL database language can be used with multidimensional arrays (MD-arrays). This second edition defines the concepts, data types, lexical and scalar expressions, operators and functions, schema and data-manipulation rules, and conformance requirements necessary for storing, retrieving and manipulating multidimensional array data inside SQL-based database systems. It is part of the ISO/IEC 9075 (SQL) series and is intended to be used alongside other SQL parts (for example Parts 1, 2, 3, 4, 9–11, 13–14, 16).
Key topics and technical requirements
- Data types and collection types: definitions and terminology for MD-array types and how they integrate with SQL data types.
- MD-array operations and operators: semantics for operators that return MD-arrays, tables, scalars or strings; rules for constructing and manipulating array values.
- MD-axis variables and subsets: notation and rules for addressing axes and array subsets (indexing, slicing).
- Expressions and functions: grammar for scalar and MD-array value expressions, aggregation, encoding, constructors and element references (see clauses on , , , ).
- Schema and DDL/DML integration: column definitions, view definitions, user-defined type declarations and store/retrieve assignment rules for MD-arrays.
- Dynamic SQL, Embedded SQL and Call-Level Interfaces: descriptor areas, host language correspondences and invocation rules for SQL that exchange MD-array values with applications.
- Information and definition schemas: metadata views (e.g., ELEMENT_TYPES, MD_EXTENTS) and base tables to describe array types and extents.
- Conformance and implementation notes: rules for claiming conformance, lists of implementation-defined and implementation-dependent elements, optional features, deprecated features and known incompatibilities (Annexes A–G).
Practical applications and users
Who benefits:
- Database vendors and implementers building SQL engines that support array data.
- Application developers and data engineers needing to store and query multidimensional scientific, image, geospatial, or analytical data in relational systems.
- Data scientists and ML engineers who prefer array-native operations inside the database to reduce ETL and improve performance.
- Standards and compliance teams verifying conformance with SQL/MDA for interoperable solutions.
Typical use cases:
- Storing and querying multidimensional sensor, satellite or medical imaging data.
- OLAP and analytical workloads that operate on tensors/cubes.
- In-database machine learning and preprocessing that manipulate arrays without exporting data.
Related standards
ISO/IEC 9075-15:2023 is intended to be used with other parts of the ISO/IEC 9075 series (SQL core, data types, dynamic SQL, embedding rules and interfaces). Consult the other 2023 editions of ISO/IEC 9075 parts for complete SQL behavior and integration details.
Open preview (PDF)Information technology — Database languages SQL — Part 15: Multidimensional arrays (SQL/MDA)
