在我的开发环境中，当我使用简单的获取所有 JQPL 查询运行 ReadAllQuery 时，我注意到在使用 EL 分析器后，有几个读取对象查询会被执行，每次都会增加我的总时间。例如，运行这样的查询会返回以下 Eclipse 配置文件输出。
@SuppressWarnings("unchecked")
public List<Person> getAllPeople(){
EntityManager entityManager = factory.createEntityManager();
List<Person> people = null;
try {
people = entityManager.createQuery("Select p from Person p where p.active = true").getResultList();
} catch (Exception e) {
// TODO: handle exception
}
finally{
entityManager.close();
if (entityManager.isOpen()) {
}
}
返回多个Register the existing object语句并查看日志输出，每个语句都在一个工作单元中完成，为什么以及如何防止这些？
[EL Finest]: connection: 2012-07-16 20:21:26.558--ServerSession(1144634498)--Connection(1713234840)--Thread(Thread["http-bio-8080"-exec-14,5,main])--Connection released to connection pool [read].
Profile(ReadAllQuery,
class=org.bixin.dugsi.domain.ApplicantSchool,
number of objects=2,
total time=3494000,
local time=3494000,
profiling time=84000,
Timer:Logging=412000,
Timer:ObjectBuilding=1670000,
Timer:SqlPrepare=24000,
Timer:ConnectionManagement=215000,
Timer:StatementExecute=455000,
Timer:Caching=68000,
Timer:DescriptorEvents=9000,
Timer:RowFetch=97000,
time/object=1747000,
)
}End profile
Register the existing object Address[id=5,persons={[Applicant[major=Bachelors in Islamic Studies,nativeLanguage=<null>,ethnicity=<null>,hispanic=<null>,religiousAffiliation=<null>,schools={[ApplicantSchool[id=8,name=John Hopkisn,fromMonth=May,fromYear=2013,toMonth=March,toYear=2011,schoolType=Highschool,creditsCompleted=unavailable,gpa=unavailable,applicant=<null>,version=1,_persistence_applicant_vh={QueryBasedValueHolder: not instantiated},_persistence_fetchGroup=<null>], ApplicantSchool[id=7,name=,fromMonth=<null>,fromYear=<null>,toMonth=<null>,toYear=<null>,schoolType=College,creditsCompleted=,gpa=,applicant=<null>,version=1,_persistence_applicant_vh={QueryBasedValueHolder: not instantiated},_persistence_fetchGroup=<null>]]},FirstName=warsame,MiddleName=a,LastName=bashir,primaryTelephone=2342342333,secondaryTelephone=,emailAddress=warsme@d.com,birthDay=Sun Jul 22 00:00:00 CDT 2012,gender=Male,DateAdded=Fri Jul 13 18:16:33 CDT 2012,address=<null>,imagePath=<null>,active=true,marital=Single,school=<null>,nativeLanguage=Arabic,ethnicity=[Asian],hispanic=No,religiousAffiliation=Islam,id=651,version=1,_persistence_school_vh={null},_persistence_address_vh={Address[id=5,persons=org.eclipse.persistence.indirection.IndirectSet@47f322c8,streetAddress=243 city join,streetAddress2=<null>,city=saudi,state_us=South Carolina (SC),zipCode=24234,country=Antarctica,version=1,_persistence_fetchGroup=<null>]},_persistence_fetchGroup=<null>]]},streetAddress=243 city join,streetAddress2=<null>,city=saudi,state_us=South Carolina (SC),zipCode=24234,country=Antarctica,version=1,_persistence_fetchGroup=<null>]
Profile(
total time=5000,
local time=5000,
Timer:DescriptorEvents=5000,
)
Profile(
total time=196000,
local time=196000,
Timer:Register=196000,
)
[EL Finest]: transaction: 2012-07-16 20:21:26.564--UnitOfWork(26103836)--Thread(Thread["http-bio-8080"-exec-14,5,main])--Register the existing object Applicant[major=Bachelors in Islamic Studies,nativeLanguage=<null>,ethnicity=<null>,hispanic=<null>,religiousAffiliation=<null>,schools={[ApplicantSchool[id=8,name=John Hopkisn,fromMonth=May,fromYear=2013,toMonth=March,toYear=2011,schoolType=Highschool,creditsCompleted=unavailable,gpa=unavailable,applicant=<null>,version=1,_persistence_applicant_vh={QueryBasedValueHolder: not instantiated},_persistence_fetchGroup=<null>], ApplicantSchool[id=7,name=,fromMonth=<null>,fromYear=<null>,toMonth=<null>,toYear=<null>,schoolType=College,creditsCompleted=,gpa=,applicant=<null>,version=1,_persistence_applicant_vh={QueryBasedValueHolder: not instantiated},_persistence_fetchGroup=<null>]]},FirstName=warsame,MiddleName=a,LastName=bashir,primaryTelephone=2342342333,secondaryTelephone=,emailAddress=warsme@d.com,birthDay=Sun Jul 22 00:00:00 CDT 2012,gender=Male,DateAdded=Fri Jul 13 18:16:33 CDT 2012,address=<null>,imagePath=<null>,active=true,marital=Single,school=<null>,nativeLanguage=Arabic,ethnicity=[Asian],hispanic=No,religiousAffiliation=Islam,id=651,version=1,_persistence_school_vh={null},_persistence_address_vh={Address[id=5,persons={[Applicant[major=Bachelors in Islamic Studies,nativeLanguage=<null>,ethnicity=<null>,hispanic=<null>,religiousAffiliation=<null>,schools={[ApplicantSchool[id=8,name=John Hopkisn,fromMonth=May,fromYear=2013,toMonth=March,toYear=2011,schoolType=Highschool,creditsCompleted=unavailable,gpa=unavailable,applicant=<null>,version=1,_persistence_applicant_vh={QueryBasedValueHolder: not instantiated},_persistence_fetchGroup=<null>], ApplicantSchool[id=7,name=,fromMonth=<null>,fromYear=<null>,toMonth=<null>,toYear=<null>,schoolType=College,creditsCompleted=,gpa=,applicant=<null>,version=1,_persistence_applicant_vh={QueryBasedValueHolder: not instantiated},_persistence_fetchGroup=<null>]]},FirstName=warsame,MiddleName=a,LastName=bashir,primaryTelephone=2342342333,secondaryTelephone=,emailAddress=warsme@d.com,birthDay=Sun Jul 22 00:00:00 CDT 2012,gender=Male,DateAdded=Fri Jul 13 18:16:33 CDT 2012,address=<null>,imagePath=<null>,active=true,marital=Single,school=<null>,nativeLanguage=Arabic,ethnicity=[Asian],hispanic=No,religiousAffiliation=Islam,id=651,version=1,_persistence_school_vh={null},_persistence_address_vh=org.eclipse.persistence.internal.indirection.QueryBasedValueHolder@6b8099d3,_persistence_fetchGroup=<null>]]},streetAddress=243 city join,streetAddress2=<null>,city=saudi,state_us=South Carolina (SC),zipCode=24234,country=Antarctica,version=1,_persistence_fetchGroup=<null>]},_persistence_fetchGroup=<null>]
Profile(
total time=1349000,
local time=1349000,
Timer:Logging=1349000,
)