Mysql 在使用继承查询字段时,是否可以停止Hibernate生成联合查询?
我有一个JPA层次结构,其中一个对象包含一组抽象类型,由不同数量的子类实现。问题是,当Hibernate尝试加载这些类时,它会生成一个查询,正常地获取主对象,但(延迟地)使用联合(在子选择中)加载这些附加对象。大致如下:Mysql 在使用继承查询字段时,是否可以停止Hibernate生成联合查询?,mysql,hibernate,jpa,database-performance,Mysql,Hibernate,Jpa,Database Performance,我有一个JPA层次结构,其中一个对象包含一组抽象类型,由不同数量的子类实现。问题是,当Hibernate尝试加载这些类时,它会生成一个查询,正常地获取主对象,但(延迟地)使用联合(在子选择中)加载这些附加对象。大致如下: select ... from ( select ... from subtable1 union select ... from subtable2 ) where parent.id = ? 这是一个效率极低的查询(父表中有10k行
select ...
from (
select ...
from subtable1
union
select ...
from subtable2
)
where parent.id = ?
这是一个效率极低的查询(父表中有10k行,所有行的每个子类中有1行获得父类中大约100条记录的整个层次结构需要几分钟,而急切查询则需要50分钟)
我不明白的是,为什么它们不仅仅是来自父表的左联接(select…from parent p left join subtable 1…left join subtable 2…
),因为这将在几分之一秒内带来所有必需的数据。有什么办法可以避免这个愚蠢的工会问题吗
到目前为止,我看到的唯一可行的解决方案是将继承类型从每个类的表更改为单个表,但这方面的权衡并不理想(包括不能使用“NOTNULL”)在专栏中,由于扩展类将属于不同的团队,甚至可能使用不同版本的软件,因此会出现维护问题)
为了防止对任何人有所帮助,我将粘贴一个由Hibernate使用此关系生成的真实查询(JPQL在开始时作为注释),此特定查询单独执行需要34秒(重写为左连接时为0.6秒):
您可以使用连接继承策略吗?如果是这样,则将其与基表上的鉴别器一起使用;Hibernate使用.hbm.xml配置支持此功能(以前版本的“使用注释配置”不起作用,我不确定最近的版本)。我将尝试一下。我正在使用Hibernate 3.3.1和注释,我可以毫无问题地混合注释和xml配置吗?我知道您可以混合它们,但您必须使用.hbm.xml映射您的基类,这样您就可以使用带有鉴别器列的用户连接策略。(请参阅Hibernate文档)。我的类都没有使用.hbm.xml进行映射,它们都是在运行时映射的(其中许多在编译时是未知的)。虽然我已经尝试过了,但它似乎可以与注释一起使用(我还没有完成所有的测试,但看起来不错)。这是一个额外的表,但对于如此巨大的性能提升来说,这是一个很小的代价。谢谢。
/* select distinct p
from PersonJpa p left join fetch p.addressOfRecords a
left join fetch a.extensions e left join fetch a.commsType c
left join fetch p.credentials cr left join fetch cr.type t
left join fetch p.serviceProfiles s left join fetch s.extensions ex
where p.id in (?1) */
SELECT DISTINCT personjpa0_.person_id AS person1_902_0_,
addressofr1_.aor_id AS aor1_899_1_,
extensions2_.id AS id903_2_,
commstypej3_.comms_type AS comms1_908_3_,
credential4_.credentials_id AS credenti1_905_4_,
credential5_.credentials_type AS credenti1_904_5_,
servicepro6_.service_profile_id AS service1_901_6_,
extensions7_.id AS id907_7_,
personjpa0_.display_name AS display2_902_0_,
personjpa0_.first_name AS first3_902_0_,
personjpa0_.initials AS initials902_0_,
personjpa0_.last_name AS last5_902_0_,
personjpa0_.title AS title902_0_,
personjpa0_.user_name AS user7_902_0_,
addressofr1_.comms_type AS comms9_899_1_,
addressofr1_.display_form AS display2_899_1_,
addressofr1_.domain AS domain899_1_,
addressofr1_.label AS label899_1_,
addressofr1_.parameters AS parameters899_1_,
addressofr1_.person_id AS person10_899_1_,
addressofr1_.preference AS preference899_1_,
addressofr1_.send_html AS send7_899_1_,
addressofr1_.service_profile_id AS service11_899_1_,
addressofr1_.user_part AS user8_899_1_,
addressofr1_.person_id AS person10_0__,
addressofr1_.aor_id AS aor1_0__,
extensions2_.aor_id AS aor2_903_2_,
extensions2_.resolution_status AS resolution1_910_2_,
extensions2_.certificate_serial_number AS certific1_914_2_,
extensions2_.device_type_name AS device2_914_2_,
extensions2_.provisioned AS provisio3_914_2_,
extensions2_.provisioning_token AS provisio4_914_2_,
extensions2_.provisioning_unique_id AS provisio5_914_2_,
extensions2_.sip_password AS sip6_914_2_,
extensions2_.username AS username914_2_,
extensions2_.voicemail_long_timeout AS voicemail8_914_2_,
extensions2_.voicemail_short_timeout AS voicemail9_914_2_,
extensions2_.clazz_ AS clazz_2_,
extensions2_.aor_id AS aor2_1__,
extensions2_.id AS id1__,
credential4_.algorithm_name AS algorithm3_905_4_,
credential4_.password AS password905_4_,
credential4_.person_id AS person4_905_4_,
credential4_.realm_id AS realm5_905_4_,
credential4_.credentials_type AS credenti6_905_4_,
credential4_.person_id AS person4_2__,
credential4_.credentials_id AS credenti1_2__,
servicepro6_.name AS name901_6_,
servicepro6_.person_id AS person3_901_6_,
servicepro6_.person_id AS person3_3__,
servicepro6_.service_profile_id AS service1_3__,
extensions7_.service_profile_id AS service2_907_7_,
extensions7_.seqprofile_id AS seqprofile1_911_7_,
extensions7_.certificate_port AS certific1_915_7_,
extensions7_.email_aor_id AS email23_915_7_,
extensions7_.emergency_numbers AS emergency2_915_7_,
extensions7_.from_domain AS from3_915_7_,
extensions7_.outbound_domain AS outbound4_915_7_,
extensions7_.pbx_aor_id AS pbx24_915_7_,
extensions7_.provisioning_delivery AS provisio5_915_7_,
extensions7_.provisioning_host AS provisio6_915_7_,
extensions7_.provisioning_port AS provisio7_915_7_,
extensions7_.server_access_call_control_port AS server8_915_7_,
extensions7_.server_access_host AS server9_915_7_,
extensions7_.server_access_number AS server10_915_7_,
extensions7_.server_access_secure_mode AS server11_915_7_,
extensions7_.sip_domain AS sip12_915_7_,
extensions7_.sip_enabled AS sip13_915_7_,
extensions7_.sip_expires AS sip14_915_7_,
extensions7_.sip_proxy AS sip15_915_7_,
extensions7_.sip_realm AS sip16_915_7_,
extensions7_.sip_transport AS sip17_915_7_,
extensions7_.voicemail_long_timeout AS voicemail18_915_7_,
extensions7_.voicemail_message_server AS voicemail19_915_7_,
extensions7_.voicemail_number AS voicemail20_915_7_,
extensions7_.voicemail_short_timeout AS voicemail21_915_7_,
extensions7_.voicemail_userid AS voicemail22_915_7_,
extensions7_.clazz_ AS clazz_7_,
extensions7_.service_profile_id AS service2_4__,
extensions7_.id AS id4__
FROM cdm.cdm_person AS personjpa0_
LEFT OUTER JOIN
cdm.cdm_address_of_record AS addressofr1_
ON personjpa0_.person_id = addressofr1_.person_id
LEFT OUTER JOIN
(SELECT NULL AS device_type_name,
id,
NULL AS provisioning_unique_id,
aor_id,
NULL AS voicemail_long_timeout,
NULL AS username,
NULL AS certificate_serial_number,
NULL AS provisioning_token,
resolution_status,
NULL AS voicemail_short_timeout,
NULL AS provisioned,
NULL AS sip_password,
1 AS clazz_
FROM cdm.sb_aor_details
UNION
SELECT device_type_name,
id,
provisioning_unique_id,
aor_id,
voicemail_long_timeout,
username,
certificate_serial_number,
provisioning_token,
NULL AS resolution_status,
voicemail_short_timeout,
provisioned,
sip_password,
2 AS clazz_
FROM cdm.fmc_remote_number_address_of_record_extension) AS extensions2_
ON addressofr1_.aor_id = extensions2_.aor_id
LEFT OUTER JOIN
cdm.cdm_comms_type AS commstypej3_
ON addressofr1_.comms_type = commstypej3_.comms_type
LEFT OUTER JOIN
cdm.cdm_credentials AS credential4_
ON personjpa0_.person_id = credential4_.person_id
LEFT OUTER JOIN
cdm.cdm_credentials_type AS credential5_
ON credential4_.credentials_type = credential5_.credentials_type
LEFT OUTER JOIN
cdm.cdm_service_profile AS servicepro6_
ON personjpa0_.person_id = servicepro6_.person_id
LEFT OUTER JOIN
(SELECT NULL AS server_access_host,
NULL AS sip_domain,
NULL AS voicemail_message_server,
NULL AS outbound_domain,
NULL AS emergency_numbers,
NULL AS provisioning_delivery,
id,
NULL AS sip_expires,
NULL AS pbx_aor_id,
NULL AS server_access_call_control_port,
NULL AS provisioning_port,
NULL AS email_aor_id,
NULL AS voicemail_number,
NULL AS voicemail_long_timeout,
NULL AS certificate_port,
NULL AS sip_enabled,
NULL AS sip_transport,
NULL AS server_access_number,
service_profile_id,
NULL AS server_access_secure_mode,
NULL AS voicemail_userid,
seqprofile_id,
NULL AS sip_realm,
NULL AS voicemail_short_timeout,
NULL AS provisioning_host,
NULL AS from_domain,
NULL AS sip_proxy,
1 AS clazz_
FROM cdm.sb_service_profile_details
UNION
SELECT server_access_host,
sip_domain,
voicemail_message_server,
outbound_domain,
emergency_numbers,
provisioning_delivery,
id,
sip_expires,
pbx_aor_id,
server_access_call_control_port,
provisioning_port,
email_aor_id,
voicemail_number,
voicemail_long_timeout,
certificate_port,
sip_enabled,
sip_transport,
server_access_number,
service_profile_id,
server_access_secure_mode,
voicemail_userid,
NULL AS seqprofile_id,
sip_realm,
voicemail_short_timeout,
provisioning_host,
from_domain,
sip_proxy,
2 AS clazz_
FROM cdm.fmc_service_profile_extension) AS extensions7_
ON servicepro6_.service_profile_id = extensions7_.service_profile_id
WHERE personjpa0_.person_id IN (1, 2, [continuous ids], 199, 200);