====== JPA Hibernate Provider ======
===== sql comments 자동 생성 =====
<code xml>
<property name="hibernate.use_sql_comments" value="true" />
</code>

===== Query Hints =====
  * http://docs.jboss.org/hibernate/stable/entitymanager/reference/en/html/objectstate.html#d0e1215
  * ''query.setHint(String name, Object value)''
  * ''org.hibernate.comment'' : 쿼리 주석 지정. PersistenceUnit 프라퍼티에 ''hibernate.use_sql_comments''가 true로 지정돼 있을 때 쿼리에 주석으로 출력된다.
  * ''org.hibernate.readOnly'' : 쿼리의 결과를 Persistence Context에 저장하지 않고, Dirty Check(변경 여부 검사 후 자동 업데이트)도 하지 않게 한다. 성능이 빨라지지만 자동 Update 작동 안함.

  * ''org.hibernate.timeout'' Query timeout in seconds ( eg. new Integer(10) )
  * ''org.hibernate.fetchSize'' Number of rows fetched by the JDBC driver per roundtrip ( eg. new Integer(50) )
  * ''org.hibernate.cacheable'' Whether or not a query is cacheable ( eg. new Boolean(true) ), defaults to false
  * ''org.hibernate.cacheMode'' Override the cache mode for this query ( eg. CacheMode.REFRESH )
  * ''org.hibernate.cacheRegion'' Cache region of this query ( eg. new String("regionName") )
  * ''org.hibernate.flushMode'' Flush mode used for this query (useful to pass Hibernate specific flush modes, in particular MANUAL).
  * ''org.hibernate.cacheMode'' Cache mode used for this query