persistence.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.1"
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
	<persistence-unit name="my-persistence-unit">
		<description>Hibernate Tips</description>
		<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
		<exclude-unlisted-classes>false</exclude-unlisted-classes>

		<properties>
			<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
			<property name="hibernate.use_sql_comments" value="true" />

			....
		</properties>
	</persistence-unit>
</persistence>

Query.java

TypedQuery q = em.createQuery(“SELECT a FROM Author a WHERE a.id = :id”, Author.class);
q.setParameter(“id”, 1L);
q.setHint(“org.hibernate.comment”, “This is my comment”);
Author a = q.getSingleResult();

Query.log

08:14:57,432 DEBUG [org.hibernate.SQL] – /* This is my comment */ select author0_.id as id1_0_, author0_.firstName as firstNam2_0_, author0_.lastName as lastName3_0_, author0_.version as version4_0_ from Author author0_ where author0_.id=?