我试图通过使用此查询来查询虽然是休眠的大量实体:
"Select * " +
" From Dossier as dossier" +
" LEFT JOIN FETCH dossier.candidat as candidat " +
" LEFT JOIN FETCH candidat.roles as role " +
" LEFT JOIN FETCH dossier.infoPerso as infoPerso " +
" LEFT JOIN FETCH dossier.etablissementOrigine as etablissementOrigine " +
" LEFT JOIN FETCH etablissementOrigine.filieres as filieres " +
" LEFT OUTER JOIN FETCH etablissementOrigine.ville as villeOrigine " +
" LEFT JOIN FETCH dossier.etatDossier as etatDossier " +
" LEFT OUTER JOIN FETCH infoPerso.fichierCNIRecto as fichierCNIRecto " +
" LEFT OUTER JOIN FETCH fichierCNIRecto.type " +
" LEFT OUTER JOIN FETCH infoPerso.fichierCNIVerso as fichierCNIVerso " +
" LEFT OUTER JOIN FETCH fichierCNIVerso.type " +
" LEFT OUTER JOIN FETCH infoPerso.fichierCV as fichierCV " +
" LEFT OUTER JOIN FETCH fichierCV.type " +
" LEFT OUTER JOIN FETCH infoPerso.fichierJAPD as fichierJAPD " +
" LEFT OUTER JOIN FETCH fichierJAPD.type " +
" LEFT OUTER JOIN FETCH infoPerso.fichierCNIVerso as fichierCNIVerso " +
" LEFT OUTER JOIN FETCH fichierCNIVerso.type " +
" LEFT OUTER JOIN FETCH infoPerso.situationFamilliale as situation "
dossiers = getEntityManager()
.createQuery(sql, Dossier.class)
.getResultList();
我可以看到hibernate正在执行第一个大型本机SQL查询。但是在那之后，Hibernate为每行生成了1个查询来加载DOssier，我不知道为什么，Dossier已经是fetchs元素的一部分...
/* load org.ema.ecandidature.dossier.Dossier */ select
dossier0_.id as id1_61_0_,
dossier0_.version as version2_61_0_,
dossier0_.valid as valid3_61_0_,
dossier0_.validSecretariat as validSec4_61_0_,
dossier0_.candidat_id as candidat7_17_0_,
dossier0_.casParticulier as casParti1_17_0_,
dossier0_.dateInscription as dateInsc2_17_0_,
dossier0_.dateSoumission as dateSoum3_17_0_,
dossier0_.entreprise_id as entrepri8_17_0_,
dossier0_.etablissementOrigine_id as etabliss9_17_0_,
dossier0_.etatDossier_id as etatDos10_17_0_,
dossier0_.infoPaiement_id as infoPai11_17_0_,
dossier0_.infoPerso_id as infoPer12_17_0_,
dossier0_.listCursusAcademique_id as listCur13_17_0_,
dossier0_.listDocumentsSupplementaires_id as listDoc14_17_0_,
dossier0_.listExpEntreprise_id as listExp15_17_0_,
dossier0_.listFormations_id as listFor16_17_0_,
dossier0_.listLangues_id as listLan17_17_0_,
dossier0_.listReferents_id as listRef18_17_0_,
dossier0_.listSejourEtranger_id as listSej19_17_0_,
dossier0_.motivationCentreInteret_id as motivat20_17_0_,
dossier0_.secretariatChangeDate as secretar4_17_0_,
dossier0_.secretariatChangeDateBackup as secretar5_17_0_,
dossier0_.validationCommentaire as validati6_17_0_
from
Dossier dossier0_
where
dossier0_.candidat_id=?
档案类:
@Entity
@BatchSize(size=100)
public class Dossier extends ValidableEntity {
/** The Constant serialVersionUID. */
private static final long serialVersionUID = 1L;
/** The etablissement origine. */
@SecretaryExport
@ManyToOne( fetch=FetchType.LAZY)
@JoinColumn()
private Etablissement etablissementOrigine;
/** The date inscription. */
@SecretaryExport
private Date dateInscription;
/** The date soumission. */
@SecretaryExport
private Date dateSoumission;
/** The date modification. */
@SecretaryExport
private Date secretariatChangeDate;
/** The date de modification backup. */
@SecretaryExport
private Date secretariatChangeDateBackup;
/** The cas particulier. */
@SecretaryExport
private Boolean casParticulier;
/** The etat dossier. */
@SecretaryExport
@ManyToOne( fetch=FetchType.LAZY)
@JoinColumn()
private EtatDossier etatDossier;
/** The candidat. */
@SecretaryExport
@OneToOne(fetch=FetchType.LAZY)
private Candidat candidat;
/** The info perso. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private InfoPerso infoPerso;
/** The list formations. */
//@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private ListFormations listFormations;
/** The list cursus academique. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private ListCursusAcademique listCursusAcademique;
/** The motivation centre interet. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private MotivationCentreInteret motivationCentreInteret;
/** The entreprise. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private Entreprise entreprise;
/** The list langues. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private ListLangues listLangues;
/** The list sejour etranger. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private ListSejourEtranger listSejourEtranger;
/** The list exp entreprise. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private ListExpEntreprise listExpEntreprise;
/** The list referents. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL},fetch=FetchType.LAZY,orphanRemoval = true)
private ListReferents listReferents;
/** The info paiement. */
@SecretaryExport
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL},fetch=FetchType.LAZY,orphanRemoval = true)
private InfoPaiement infoPaiement;
/** The avis jury. */
@OneToMany(mappedBy= "dossier" , cascade = { CascadeType.ALL},fetch=FetchType.LAZY,orphanRemoval = true)
private Set<AvisJury> avisJury = new HashSet<>();
/** The list documents supplementaires. */
@Obligatoire
@ObligatoireSecretariat
@OneToOne(cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private ListDocumentsSupplementaires listDocumentsSupplementaires;
/** The list fichier. */
@OneToMany(mappedBy = "dossier", cascade = { CascadeType.ALL },fetch=FetchType.LAZY,orphanRemoval = true)
private Set<Fichier> listFichier;
/** The list avis examinateur. */
@OneToMany(mappedBy= "dossier" , cascade = { CascadeType.ALL},fetch=FetchType.LAZY,orphanRemoval = true)
private Set<AvisExaminateur> listAvisExaminateur;
/** The list commentaire. */
@OneToMany(cascade = { CascadeType.ALL},fetch=FetchType.LAZY,orphanRemoval = true)
private Set<Commentaire> listCommentaire;
/** The validation commentaire. */
@Column(length = 500)
@Pattern(regexp="^(.|\n|\r|\t)*$")//accepte tous les caractères et les retours lignes
private String validationCommentaire;
}
怎么了
参考方案
怎么了
正如我在书High-Performance Java Persistence中解释的那样，除非计划修改实体，否则永远不要获取实体。因此，如果仅需要只读视图，则应使用DTO projection instead。
假设由于计划对图进行修改而确实需要获取整个图，则必须使用以下获取策略:
您可以在第一个查询中获取尽可能多的子@OneToOne和@ManyToOne实体关联，也可以在OST中最多获取一个@OneToMany或@ManyToMany。
对于其余的@OneToMany或@ManyToMany，您必须使用辅助查询。但是，您不想在N+1 fashion中执行此操作，因此您需要在传递您用第一个查询获取的根实体的同时为那些查询运行JPQL查询。
请记住，如果将辅助集合重新组装到根实体上，则会在根实体上触发一些不必要的修改。因此，如果要将根实体传递到Web层，则应以只读模式获取它们。
同样，如果不需要实体，则应获取DTO投影，并使用ResultTransfomer将类似表格的投影转换为DTO图，如this article中所述。
但是在那之后，Hibernate为每一行生成了另外一个查询
加载档案，我不知道为什么，档案已经是获取的一部分
元素...
从这些映射中，尚不清楚执行该查询的原因，但您可以在Hibernate的datasource-proxy level处轻松调试它，并查看堆栈跟踪以查看触发它的原因。
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