JPQL创建N + 1查询

Question

IncidentHdr表与IncidentHdrDtl有一对多的映射。

IncidentHdr的实体类，这里将incidentDtls称为Lazy

@Entity
@Table(name="IR_TB_INCIDENT_HDR")
public class IncidentHdr implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @SequenceGenerator(name="IR_TB_INCIDENT_HDR_INCIDENTID_GENERATOR", sequenceName="IR_SEQ_INCIDENT_ID")
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="IR_TB_INCIDENT_HDR_INCIDENTID_GENERATOR")
    @Column(name="INCIDENT_ID")
    private long incidentId;

    @Column(name="ACTION_TAKEN")
    private String actionTaken;

    @NotFound(action=NotFoundAction.IGNORE)
    @ManyToOne()
    @JoinColumn(name = "CAT_CODE")
    private CategoryMast categoryMast;


    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="CREATED_TIME")
    private Date createdTime;

    @Column(name="INCIDENT_SR_NO")
    private String incidentSrNo;

    @NotFound(action=NotFoundAction.IGNORE)
    @ManyToOne()
    @JoinColumn(name = "INCIDENT_STATUS")
    private IncidentStatus incidentStatus;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="INCIDENT_TIME")
    private Date incidentTime;

    @NotFound(action=NotFoundAction.IGNORE)
    @ManyToOne()
    @JoinColumn(name = "LOCATION")
    private LocationMast locationMast;


    @NotFound(action=NotFoundAction.IGNORE)
    @ManyToOne()
    @JoinColumn(name = "SUB_CAT_CODE")
    private SubCategoryMast subCategoryMast;


    @OneToMany(cascade = {CascadeType.PERSIST,CascadeType.MERGE, CascadeType.REMOVE}, fetch = FetchType.LAZY,  mappedBy="incidentHdr")
    private Set<IncidentDtl> incidentDtls;

    public IncidentHdr() {
    }

}

事件详细信息的实体类。

@Entity
@Table(name="IR_TB_INCIDENT_DTL")
public class IncidentDtl implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @SequenceGenerator(name="IR_TB_INCIDENT_DTL_MESSAGEID_GENERATOR", sequenceName="IR_SEQ_MESSAGE_ID")
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="IR_TB_INCIDENT_DTL_MESSAGEID_GENERATOR")
    @Column(name="MESSAGE_ID")
    private long messageId;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="ENTRY_TIME")
    private Date entryTime;

    @Column(name="ENTRY_USER")
    private Long entryUser;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="INCIDENT_ID")
    private IncidentHdr incidentHdr;

    @Column(name="MSG_DESC")
    private String msgDesc;

    @Column(name="MSG_TYPE")
    private String msgType;

    public IncidentDtl() {
    }

}

自定义repo类，它将具有初始选择查询（GET_INCIDENT_DETAILS）。 将根据输入dto追加新条件，并在此处形成完整查询。

public class IncidentReportingRepoCustomImpl implements IncidentReportingRepoCustom{


    private static final MohLogger logger = MohLogFactory.getLoggerInstance(IncidentReportingRepoCustomImpl.class.getName());

    @PersistenceContext
    private EntityManager em;

    @Override
    public PaginationDto fetchIncidents(IncidentHdrSearchDto incidentHdrSearchDto) throws BusinessException {

        PaginationDto inPaginationDto = new PaginationDto();
        List<IncidentHdr> incidentHdrs = null;
        StringBuilder query = null;
        try{
            query = new StringBuilder();
            query.append(ReposJPQL.GET_INCIDENT_DETAILS);

            Map<String, Object> parameters = new HashMap<String, Object>();
            List<String> criteria = new ArrayList<String>();

            createIncidentSearchQuery(parameters,criteria, incidentHdrSearchDto);

            //append the query criteria          
            if (criteria.size() > 0) {
                for (int i = 0; i < criteria.size(); i++) {
                    query.append(" AND ");
                    query.append(criteria.get(i));
                }
            }   

            Query q = em.createQuery(query.toString());
            //logger.info("@@@@@@@@@@@@@@ QUERY @@@@@@@@@@@@@@ "+ query.toString());

            //set parameters
            for (Entry<String, Object> entry : parameters.entrySet()) {
                q.setParameter(entry.getKey(), entry.getValue());
            }

                inPaginationDto.setTotalRecords(q.getResultList().size());

            //pagination
            if(inPaginationDto.getTotalRecords() > incidentHdrSearchDto.getMaxResult() && incidentHdrSearchDto.getFirstResult() != null && incidentHdrSearchDto.getMaxResult() != null){
                q.setFirstResult(incidentHdrSearchDto.getFirstResult());        
                q.setMaxResults(incidentHdrSearchDto.getMaxResult());
            }

            incidentHdrs = q.getResultList();
        }catch(IllegalArgumentException | IllegalStateException | DataAccessException | EntityNotFoundException e){
            logger.error(e.getMessage());
            throw new BusinessException(e);
        }
        inPaginationDto.setPaginatedList(incidentHdrs);
        return inPaginationDto;
    }

/**
 * To generate query for incident search
 * @param parameters
 * @param criteria
 * @param incidentHdrDto
 */


private void createIncidentSearchQuery(Map<String, Object> parameters, List<String> criteria, IncidentHdrSearchDto incidentHdrSearchDto) {
        if(incidentHdrSearchDto.getIncidentSrNo() != null) {
            criteria.add("upper(inc.incidentSrNo) like :incidentSrNo");
            parameters.put("incidentSrNo" ,"%"+ incidentHdrSearchDto.getIncidentSrNo().toUpperCase()+"%");
        }

        if(incidentHdrSearchDto.getCategoryMast() != null) {
            criteria.add("inc.categoryMast.catCode = :catCode");
            parameters.put("catCode", incidentHdrSearchDto.getCategoryMast().getCatCode());
        }   


        if(incidentHdrSearchDto.getLocationMast() != null) {
            criteria.add("inc.locationMast.locCode = :location");
            parameters.put("location", incidentHdrSearchDto.getLocationMast().getLocCode());
        }

        if(incidentHdrSearchDto.getPatientId() != null) {
            criteria.add("inc.patientId = :patientId");
            parameters.put("patientId", incidentHdrSearchDto.getPatientId());
        }

        if(incidentHdrSearchDto.getAmsWorkOrderNo() != null) {
            criteria.add("inc.amsWorkOrderNo = :amsWorkOrderNo");
            parameters.put("amsWorkOrderNo", incidentHdrSearchDto.getAmsWorkOrderNo());
        }

        if(incidentHdrSearchDto.getTypeMast() != null){
            criteria.add("cm.typeCode = :typeCode");
            parameters.put("typeCode", incidentHdrSearchDto.getTypeMast().getTypeCode());
        }

        if(incidentHdrSearchDto.getSentinelYn() != null){
            if(incidentHdrSearchDto.getSentinelYn()){
                criteria.add("inc.sentinelYn = :sentinelYn");
                parameters.put("sentinelYn", "Y");
            }else{
                criteria.add("inc.sentinelYn = :sentinelYn");
                parameters.put("sentinelYn", "N");
            }
        }


        //get incidents which are reported with in 'x' hours.
        if(incidentHdrSearchDto.getReportedWithIn() != null){
            criteria.add(" (24 *(inc.createdTime - inc.incidentTime )) <= :withInHours");
            parameters.put("withInHours", incidentHdrSearchDto.getReportedWithIn());
        }



        //severity based search, data need to fetch from the view.
        if(incidentHdrSearchDto.getSeverityCode() != null){
            criteria.add("inc.categoryMast.catCode IN ("+ReposJPQL.GET_CAT_SEVERITY+")"
                    + " OR inc.subCategoryMast.subCatCode IN ("+ReposJPQL.GET_SUB_CAT_SEVERITY+")");
            parameters.put("severityCode", incidentHdrSearchDto.getSeverityCode());
        }
    }
}

初始选择查询详细信息，

GET_INCIDENT_DETAILS = public String GET_INCIDENT_DETAILS = "SELECT inc FROM IncidentHdr inc LEFT JOIN inc.categoryMast cm LEFT JOIN inc.subCategoryMast sub LEFT OUTER JOIN inc.incidentDtls  WHERE 1 = 1" ;

遇到IncidentHdr和IncidentDtl的N + 1问题。