| Version:
- Spring Boot v2.2.7
- Hibernate v5.4.15.Final
- `spring-data-jpa-entity-graph` v2.2.8
I have the following `@Entity` in my application.
@Entity(name="DemoAccount")
@Table(name="staff")
@Getter @Setter @FieldNameConstants
@NoArgsConstructor
public class Account {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
protected Long id;
@Column(name="username", nullable=false)
private String userId;
private String name;
@ManyToOne(fetch=FetchType.LAZY)
@LazyToOne(LazyToOneOption.NO_PROXY)
@LazyGroup("nationality")
@JoinColumn(name="nationality", referencedColumnName="code")
private Nationality nationality;
}
@Entity(name="DemoNationality ")
@Table(name="nationality ")
@Getter @Setter @FieldNameConstants
@NoArgsConstructor
public class Nationality {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
protected Long id;
@Column(name="code", nullable=false)
private String code;
private String name;
}
I'm using the following @Repository to look for Account.
@Repository
public interface AccountRepo extends EntityGraphJpaRepository<Account, Long> {
Optional<Account> findByUserId(String userId, EntityGraph entityGraph);
}
My test endpoint contains a simple method.
@CustomerTransactional
@GetMapping("/profile")
public void testProfile(@RequestParam String userId) {
Optional<Account> account = accountRepo.findByUserId(userId, EntityGraphs.create(Account.Fields.nationality));
if (account.isPresent()) {
System.out.println(account.get().getName());
System.out.println(account.get().getNationality().getName());
}
}
When I execute this endpoint, this is what I'm seeing in the log.
2020-05-24 16:18:26,492 DEBUG [http-nio-9000-exec-1] org.hibernate.SQL :
/* select
generatedAlias0
from
DemoAccount as generatedAlias0
where
generatedAlias0.userId=:param0 */ select
account0_.id as id1_61_0_,
nationalit1_.id as id1_35_1_,
account0_.name as name4_61_0_,
account0_.username as username6_61_0_,
nationalit1_.code as code2_35_1_,
nationalit1_.name as name4_35_1_
from
staff account0_
left outer join
nationality nationalit1_
on account0_.nationality=nationalit1_.code
where
account0_.username=?
2020-05-24 16:18:26,492 TRACE [http-nio-9000-exec-1] org.hibernate.type.descriptor.sql.BasicBinder : binding parameter [1] as [VARCHAR] - [90000010]
Edgar Rey Tann
2020-05-24 16:18:26,506 DEBUG [http-nio-9000-exec-1] org.hibernate.SQL :
/* sequential select
com.ft.demo.db.customer.domain.Account */ select
account_.nationality as nationa22_61_
from
staff account_
where
account_.id=?
2020-05-24 16:18:26,507 TRACE [http-nio-9000-exec-1] org.hibernate.type.descriptor.sql.BasicBinder : binding parameter [1] as [BIGINT] - [660]
Indonesian
As you can see, in the middle of the account name and the nationality name, there's an extra query just to select the nationality field. It means if I have 50 records, 50 additional queries got executed. May I know how I can fix this behaviour? Below is what I used in pom.xml to activate Hibernate Bytecode Enhancer
<build>
<plugins>
<plugin>
<groupId>org.hibernate.orm.tooling</groupId>
<artifactId>hibernate-enhance-maven-plugin</artifactId>
<version>${hibernate.version}</version>
<executions>
<execution>
<configuration>
<failOnError>true</failOnError>
<enableLazyInitialization>true</enableLazyInitialization>
<enableDirtyTracking>true</enableDirtyTracking>
<enableAssociationManagement>true</enableAssociationManagement>
</configuration>
<goals>
<goal>enhance</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
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