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Fix N+1 Query Performance Issue in Vets Endpoint-created-by-agentic #92

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Fix N+1 Query Performance Issue in Vets Endpoint-created-by-agentic #92

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5589088
fix: Change specialties fetch type to LAZY to prevent N+1 queries
shaykeren Jul 24, 2025
4269eea
fix: Add JOIN FETCH query and optimize caching for vets
shaykeren Jul 24, 2025
0422ccf
fix: Add indexes on vet_specialties join table to improve query perfo…
shaykeren Jul 24, 2025
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4 changes: 2 additions & 2 deletions src/main/java/org/springframework/samples/petclinic/vet/Vet.java
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@
@Table(name = "vets")
public class Vet extends Person {

@ManyToMany(fetch = FetchType.EAGER)
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "vet_specialties", joinColumns = @JoinColumn(name = "vet_id"),
inverseJoinColumns = @JoinColumn(name = "specialty_id"))
private Set<Specialty> specialties;
Expand Down Expand Up @@ -76,4 +76,4 @@ public void addSpecialty(Specialty specialty) {
getSpecialtiesInternal().add(specialty);
}

}
}
6 changes: 5 additions & 1 deletion src/main/java/org/springframework/samples/petclinic/vet/VetRepository.java
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Expand Up @@ -19,6 +19,8 @@
import org.springframework.dao.DataAccessException;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.EntityGraph;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.Repository;
import org.springframework.transaction.annotation.Transactional;

Expand All @@ -41,6 +43,7 @@ public interface VetRepository extends Repository<Vet, Integer> {
* Retrieve all <code>Vet</code>s from the data store.
* @return a <code>Collection</code> of <code>Vet</code>s
*/
@Query("SELECT DISTINCT vet FROM Vet vet LEFT JOIN FETCH vet.specialties")
@Transactional(readOnly = true)
@Cacheable("vets")
Collection<Vet> findAll() throws DataAccessException;
Expand All @@ -51,8 +54,9 @@ public interface VetRepository extends Repository<Vet, Integer> {
* @return
* @throws DataAccessException
*/
@EntityGraph(attributePaths = {"specialties"})
@Transactional(readOnly = true)
@Cacheable("vets")
Page<Vet> findAll(Pageable pageable) throws DataAccessException;

}
}
6 changes: 4 additions & 2 deletions src/main/resources/db/mysql/schema.sql
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Expand Up @@ -16,7 +16,9 @@ CREATE TABLE IF NOT EXISTS vet_specialties (
specialty_id INT(4) UNSIGNED NOT NULL,
FOREIGN KEY (vet_id) REFERENCES vets(id),
FOREIGN KEY (specialty_id) REFERENCES specialties(id),
UNIQUE (vet_id,specialty_id)
UNIQUE (vet_id,specialty_id),
INDEX idx_vet_specialties_vet (vet_id),
INDEX idx_vet_specialties_specialty (specialty_id)
) engine=InnoDB;

CREATE TABLE IF NOT EXISTS types (
Expand Down Expand Up @@ -52,4 +54,4 @@ CREATE TABLE IF NOT EXISTS visits (
visit_date DATE,
description VARCHAR(255),
FOREIGN KEY (pet_id) REFERENCES pets(id)
) engine=InnoDB;
) engine=InnoDB;