ObjectRelational

ObjectRelational refers to technologies and approaches that blend relational database concepts with object-oriented features. In practice, object-relational systems extend the relational model with constructs drawn from object-oriented programming, aiming to support more complex data while still using SQL as the core query language.

Core features commonly associated with object-relational databases include user-defined types and structured types, table or type inheritance, and the ability to attach methods or operators to data types. These systems also support complex and nested data, such as arrays or composite types, and provide extensions for querying and indexing such data. The goal is to model real-world entities more naturally than with flat relational tables, while retaining the strengths of relational querying, constraints, and portability.

Notable examples and history: PostgreSQL is a widely cited open-source example that implements many object-relational features, including composite types, arrays, and some form of inheritance. Oracle and Informix have offered object-relational capabilities, and SQL:1999 (and subsequent standards) introduced object-relational features to formalize support for structured, nested, and typed data within the SQL ecosystem.

Relationship to object-relational mapping: ObjectRelational often describes native database capabilities, whereas Object-Relational Mapping (ORM) refers to software layers that map application objects to relational tables. ORMs sit outside the database, while object-relational features are built into the DBMS to store and query complex data more naturally.

Advantages and drawbacks: Object-relational approaches can reduce impedance mismatch between applications and storage, enable richer data models, and improve performance for certain workloads. They can also introduce complexity, vendor-specific extensions, and portability challenges compared with strictly relational systems.