Java hbm.xml multiple index of one column

For example,

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="com.sql.index">
    <class name="User">
        <id name="id" type="long">
            <generator class="native" />
        </id>
        <property name="firstName" type="string" index="IDX_FIRST_NAME" />
        <property name="lastName" type="string" />
        <property name="address" type="string" />
        <property name="field_1" type="long" />
        <property name="field_2" type="long" />
    </class>
</hibernate-mapping>

If I want the field_1 and field_2 has 2 indexes description. Can I do the following thing? Or How to achieve it ?

        <property name="field_1" type="long" index="idx_1,idx_2"/>
        <property name="field_2" type="long" index="idx_1,idx_3"/>

The field_1 and field_2 will has 2 index for their self.

---

I refer the hibernate 3.6, 5.1.4.2 Property mapping with hbm.xml, it seems like the index field can be assigned by only one column.

---

PS,

The project is some kind old, and is maintained by many people, so I cannot use annotation syntax to add index.

I found the post and give it a try.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="com.sql.index">
    <class name="User">
        <id name="id" type="long">
            <generator class="native" />
        </id>
        <property name="firstName" type="string" index="IDX_FIRST_NAME" />
        <property name="lastName" type="string" />
        <property name="address" type="string" />
        <property name="field_1" type="long" index="idx_2"/>
        <property name="field_2" type="long" index="idx_3"/>
    </class>
    <database-object>
        <create>
            CREATE INDEX idx_1 ON User (field_1, field_2)
        </create>
        <drop></drop>
    </database-object>
</hibernate-mapping>

---

This problem can be solved by <database-object>, by writing native sql syntax to create index.

---

UPDATE, 2018/11

For unique constraint with multiple properties, someone has answered it.

Use properties tag

<properties name="uk1" unique="true">
        <property name="username" .../>
        <many-to-one name="client" .../>
</properties>

<properties name="uk2" unique="true">
        <property name="email" .../>
        <many-to-one name="client" update="false" insert="false" .../>
</properties>