spring mvc - Hibernate using two oracle database, Error: cannot simultaneously fetch multiple bags -

i have 2 separate oracle schema pool information , update. somehow when have 2 hibernate.dialect pointing same dialect, give me simultaneously fetch multiple bags error. if change 1 of org.hibernate.dialect.mysqldialect, error disappear , compile table did not generate. question hibernate. while datasource mysql, able generate of table need, when switch datasource oracle, generate 3 table.

below persistent.xml

<!-- hibernate sessionfactory --> <bean id="sessionfactory"     class="org.springframework.orm.hibernate3.annotation.annotationsessionfactorybean"     p:datasource-ref="datasource">     <property name="packagestoscan" value="edu.byuh.checklist.domain" />       <property name="hibernateproperties">         <value>             hibernate.dialect=org.hibernate.dialect.oracle10gdialect             hibernate.transaction.factory_class=org.hibernate.transaction.jdbctransactionfactory             autoreconnect=true             hibernate.show_sql=true             hibernate.hbm2ddl.auto=update             hibernate.default_schema=checklist                            hibernate.flushmode=never          </value>     </property> </bean>  <bean id="orasessionfactory"     class="org.springframework.orm.hibernate3.annotation.annotationsessionfactorybean"     p:datasource-ref="oradatasource">     <!-- <property name="annotatedclasses"> <list> <value>edu.byuh.checklist.oradomain.psuserdetails</value>          <value>edu.byuh.checklist.oradomain.housingassignment</value> <value>edu.byuh.checklist.oradomain.housingfee</value>          </list> </property> -->     <property name="packagestoscan" value="edu.byuh.checklist.oradomain" />     <property name="hibernateproperties">         <value>             hibernate.dialect=org.hibernate.dialect.oracle10gdialect             <!-- hibernate.show_sql=true -->             hibernate.transaction.factory_class=org.hibernate.transaction.jdbctransactionfactory             autoreconnect=true             hibernate.default_schema=sysadm                <!-- maxconnectionage = 4 * 60 * 60 maxidletimeexcessconnections = 30                  * 60 -->             hibernate.jdbc.batch_size=${hibernate.jdbc.batch_size}             hibernate.c3p0.max_size=${hibernate.c3p0.max_size}             hibernate.c3p0.min_size=${hibernate.c3p0.min_size}             hibernate.c3p0.timeout=${hibernate.c3p0.timeout}             hibernate.c3p0.max_statements=${hibernate.c3p0.max_statements}             hibernate.c3p0.idle_test_period=${hibernate.c3p0.idle_test_period}         </value>     </property>  </bean> <!-- <beans:prop key="hibernate.transaction.factory_class"> org.hibernate.transaction.jdbctransactionfactory      </beans:prop> -->   <!-- <beans:property name="hibernateproperties"> <beans:props> <beans:prop      key="hibernate.dialect"> org.hibernate.dialect.oracle10gdialect</beans:prop>      <beans:prop key="hibernate.show_sql">true</beans:prop> <beans:prop key="hibernate.transaction.factory_class">      org.hibernate.transaction.jdbctransactionfactory </beans:prop> prop key="hibernate.hbm2ddl.auto">update</prop      <beans:prop key="hibernate.default_schema">sysadm</beans:prop> </beans:props>      </beans:property> </beans:bean> -->  <!-- read in daos hibernate package --> <context:component-scan base-package="edu.byuh.checklist.dao.hibernate" />  <!-- transaction config --> <bean id="transactionmanager"     class="org.springframework.orm.hibernate3.hibernatetransactionmanager"     p:sessionfactory-ref="sessionfactory" />  <bean id="oratransactionmanager"     class="org.springframework.orm.hibernate3.hibernatetransactionmanager"     p:sessionfactory-ref="orasessionfactory" /> <!-- <aop:config proxy-target-class="true"/> -->   <tx:annotation-driven transaction-manager="transactionmanager" /> 

below of domain class

@suppresswarnings("serial") @entity @table(name = "checklistitem") @inheritance(strategy = inheritancetype.single_table) @discriminatorcolumn(name="itemtype", discriminatortype=discriminatortype.string) public abstract class checklistitem implements domainobject, comparable<checklistitem>{   //@sequencegenerator(name = "mysequence", sequencename = "my_seq", allocationsize=1) @sequencegenerator(name = "hibernate_sequence", sequencename = "checklistitem", allocationsize=1) @id @generatedvalue(strategy = generationtype.table) private integer id; private string title; private string subtitle; private boolean published; @column(length=2560) private string contenttxt; //list of student attributes @elementcollection(fetch = fetchtype.eager) @enumerated(enumtype.string) private list<studentattribute> appliesto; 

another domain class

@entity @primarykeyjoincolumn(name = "fk_id", referencedcolumnname = "id") public class infoitemuser extends checklistitemuser implements domainobject {  private integer tries; 

the problem you're facing explained in great blog http://blog.eyallupu.com/2010/06/hibernate-exception-simultaneously.html explains query example, why can't have multiple bags, , proposes solution

you have 2 eagerly fetched collections hibernate due mapping combination interprets bag. 1 visible code posted in question

@elementcollection(fetch = fetchtype.eager) @enumerated(enumtype.string) private list<studentattribute> appliesto; 

you have 3 possible solutions:

• have collections lazily loaded
• move type list set if business logic allows it
• annotate collections @indexcolumn