Identity map pattern

In the design of database management systems, the identity map pattern is a database access design pattern used to improve performance by providing a context-specific, in-memory cache to prevent duplicate retrieval of the same object data from the database.[1]

If the requested data has already been loaded from the database, the identity map returns the same instance of the already instantiated object, but if it has not been loaded yet, it loads it and stores the new object in the map. In this way, it follows a similar principle to lazy loading.

There are four types of Identity Map

Explicit
Generic
Session
Class

References

Fowler, Martin (2003). Patterns of Enterprise Application Architecture. Addison-Wesley. pp. 195–199. ISBN 0-321-12742-0.

Software design patterns
Creational	Abstract factory Builder Dependency injection Factory method Lazy initialization Multiton Object pool Prototype RAII Singleton
Structural	Adapter Bridge Composite Decorator Delegation Facade Flyweight Front controller Marker interface Module Proxy Twin
Behavioral	Blackboard Chain of responsibility Command Interpreter Iterator Mediator Memento Null object Observer Servant Specification State Strategy Template method Visitor
Functional	Monoid Functor Applicative Monad Comonad Free monad HOF Currying Function composition Closure Generator
Concurrency	Active object Actor Balking Barrier Binding properties Coroutine Compute kernel Double-checked locking Event-based asynchronous Fiber Futex Futures and promises Guarded suspension Immutable object Join Lock Messaging Monitor Nuclear Proactor Reactor Read write lock Scheduler STM Thread pool Thread-local storage
Architectural	ADR Active record Broker Client–server CBD DAO DTO DDD ECB ECS EDA Front controller Identity map Interceptor Implicit invocation Inversion of control Model 2 MOM Microservices MVA MVC MVP MVVM Monolithic Multitier Naked objects ORB P2P Publish–subscribe PAC REST SOA Service locator Specification
Cloud Distributed	Ambassador Anti-Corruption Layer Bulkhead Cache-Aside Circuit Breaker CQRS Compensating Transaction Competing Consumers Compute Resource Consolidation Event Sourcing External Configuration Store Federated Identity Gatekeeper Index Table Leader Election MapReduce Materialized View Pipes Filters Priority Queue Publisher-Subscriber Queue-Based Load Leveling Retry Scheduler Agent Supervisor Sharding Sidecar Strangler Throttling Valet Key
Other	Business delegate Composite entity Intercepting filter Lazy loading Mangler Mock object Type tunnel Method chaining
Books	Design Patterns Enterprise Integration Patterns Code Complete POSA
People	Christopher Alexander Erich Gamma Ralph Johnson John Vlissides Grady Booch Kent Beck Ward Cunningham Martin Fowler Robert Martin Jim Coplien Douglas Schmidt Linda Rising
Communities	The Hillside Group The Portland Pattern Repository

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Identity map pattern

See also

References