Esquema por defecto en JPA

orm.xml

<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm
                        http://java.sun.com/xml/ns/persistence/orm_2_0.xsd"
    version="2.0">
    <persistence-unit-metadata>
        <persistence-unit-defaults>
            <schema>MYSCHEMA</schema>
        </persistence-unit-defaults>
    </persistence-unit-metadata>
    <sequence-generator name="IdentitySeq"
        sequence-name="SEQ_GEN_IDENTITY" allocation-size="50" />
</entity-mappings>