[hibernate-issues] [Hibernate-JIRA] Created: (HHH-4865) criteria on association w/ fetch=join, get n+1 queries
criteria on association w/ fetch=join, get n+1 queries
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Key: HHH-4865
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4865
Project: Hibernate Core
Issue Type: Bug
Components: query-criteria
Affects Versions: 3.2.7
Environment: Hibernate 3.2.7.ga
Reporter: Kevin Howard
Priority: Minor
When I specify a restriction on an one-to-many association in a criteria query, Hibernate
executes n+1 queries even though the first query is joining the two tables correctly with
an inner join. This happens if I use createAlias or createCriteria to specify the
restriction on the association. If I don't specify a restriction on the association
then I do not get n+1 queries and the association is populated. This seems like a bug as
all the data is returned in the initial query and the following queries are not needed. I
posted this in the forum (https://forum.hibernate.org/viewtopic.php?f=1&t=1002270)
with no response.
Criteria Query:
final DetachedCriteria criteria = DetachedCriteria.forClass(A.class);
criteria.add(Restrictions.eq("column1", value1))
.createAlias("someSetofB", "h")
.add(Restrictions.in("h.code", new String[]
{"A","B","C"}));
final List<A> list = getHibernateTemplate().findByCriteria(criteria);
Association Mapping:
<set name="someSetofB" lazy="false" fetch="join">
<key>
<column name="SOME_ID" />
</key>
<one-to-many class="B" />
</set>
SQL:
select ..(every column from A and B).. from A this_ inner join B h1_ on
this_.SOME_ID=h1_.SOME_ID where this_.COLUMN_ONE=? and h1_.CODE in (?, ?, ?)
select .... from B someSetOfB0_ where someSetOfB0_.SOME_ID=?
select .... from B someSetOfB0_ where someSetOfB0_.SOME_ID=?
..... selects for as many A's returned by first query
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