If you use HibernateService for JDBC connections management you will need to specify explicitly the default schema by setting "hibernate.default_schema" property in the configuration of HibernateService.
Here is an example:
<component>
<key>org.exoplatform.services.database.HibernateService</key>
<jmx-name>database:type=HibernateService</jmx-name>
<type>org.exoplatform.services.database.impl.HibernateServiceImpl</type>
<init-params>
<properties-param>
<name>hibernate.properties</name>
<description>Default Hibernate Service</description>
...........
</properties-param>
</init-params>
</component>