Difference between JPA Repository, MongoRepository, and CRUD Repository ?

In Spring Data, different repositories provide abstraction for various data storage solutions. The main repositories used are:

1. CRUD Repository → Provides basic CRUD operations.
2. JPA Repository → Extends CRUDRepository, provides additional JPA-specific methods.
3. Mongo Repository → Used for MongoDB, extending CrudRepository with MongoDB-specific features.

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CRUD Repository

CrudRepository<T, ID> is the base interface in Spring Data that provides basic CRUD (Create, Read, Update, Delete) operations.

Features

• Supports generic CRUD operations (save(), findById(), delete(), etc.).
• Works with relational (JPA) and NoSQL (MongoDB, Cassandra, etc.) databases.
• Requires minimal boilerplate code.

Example

public interface EmployeeRepository extends CrudRepository<Employee, Long> {
}

Available Methods

Optional<T> findById(ID id);
void deleteById(ID id);
void delete(T entity);
<S extends T> S save(S entity);
Iterable<T> findAll();
long count();

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2. JPA Repository (For Relational Databases)

JpaRepository<T, ID> extends CrudRepository<T, ID> and PagingAndSortingRepository<T, ID>, adding extra methods for JPA-based operations.

Features

• Pagination & Sorting (findAll(Pageable p), findAll(Sort s)).
• Batch operations (saveAll() for bulk insert/update).
• Flush & Delete methods (deleteInBatch(), flush()).
• Supports JPQL and native queries.

Example

public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}

Available Methods

In addition to CrudRepository methods:

List<T> findAll();
List<T> findAll(Sort sort);
Page<T> findAll(Pageable pageable);
<S extends T> List<S> saveAll(Iterable<S> entities);
void flush();
<S extends T> S saveAndFlush(S entity);
void deleteInBatch(Iterable<T> entities);

Use Case:
For relational databases like MySQL, PostgreSQL, Oracle using Hibernate as JPA provider.

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Mongo Repository (For MongoDB – NoSQL)

MongoRepository<T, ID> extends CrudRepository<T, ID>, providing MongoDB-specific features.

Features

• Works with MongoDB (NoSQL), supports BSON documents instead of relational tables.
• Supports aggregation operations (findBy...(), deleteBy...()).
• Uses MongoDB Query Language (not JPQL).
• Provides custom queries using JSON-style query DSL.

Example

public interface EmployeeRepository extends MongoRepository<Employee, String> {
}

Available Methods

Same as CrudRepository, but optimized for MongoDB:

List<T> findAll();
List<T> findByDepartment(String department);
List<T> findByAgeBetween(int start, int end);
long count();

Use Case:
For MongoDB NoSQL databases, storing data as JSON-like BSON documents instead of relational tables.

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Comparison Table

Feature	CrudRepository	JpaRepository	MongoRepository
Database Type	Any (SQL & NoSQL)	Relational (JPA)	NoSQL (MongoDB)
Basic CRUD	✅ Yes	✅ Yes	✅ Yes
Pagination & Sorting	❌ No	✅ Yes (findAll(Pageable))	✅ Yes (findAll(Pageable))
Batch Processing	❌ No	✅ Yes (saveAll())	✅ Yes (saveAll())
Native Queries	❌ No	✅ Yes (@Query)	✅ Yes (@Query)
Flush & Batch Delete	❌ No	✅ Yes (flush(), deleteInBatch())	❌ No
Use Case	Basic CRUD	Relational Databases (MySQL, PostgreSQL, etc.)	MongoDB

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Which Repository to Use?

• Use CrudRepository when you only need basic CRUD operations.
• Use JpaRepository when working with SQL databases and need pagination, sorting, and batch processing.
• Use MongoRepository when working with MongoDB (NoSQL databases).