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Data & Analytics · Intermediate

Object-Relational Mapping (ORM)

A technique and set of libraries (Hibernate, Entity Framework, SQLAlchemy) that map programming objects to relational tables.

Definition

ORMs reduce boilerplate SQL and provide database portability, but they can generate inefficient queries such as the N+1 problem. They also reduce SQL injection risk by parameterizing queries.

Exam tip

Lazy loading inside a loop that triggers one query per row is the ORM-generated N+1 problem.

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