[hibernate-issues] [Hibernate-JIRA] Issue Comment Edited: (HHH-2666) subselect fetching ignores max results
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http://opensource.atlassian.com/projects/hibernate/browse/HHH-2666?page=c...
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umanath kandhallu edited comment on HHH-2666 at 1/19/12 11:29 PM:
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i used following as a work around, where i set 200 as maxResults in parent criteria
query.
i defined parent child @OneToMany with in below fashion instead of using subselect:
@Fetch(FetchMode.JOIN)
@BatchSize(size=200)
hibernate used subquery to fetch child records like one below:
select * from child where parentid in (?,?,?...)
instead of
select * from child where parentid in (criteria query which used to select parent)
was (Author: umanathkm(a)gmail.com):
i used following as a work around
@Fetch(FetchMode.JOIN)
@BatchSize(size=200)
so the generated query was like
select * from child where parentid in (?,?,?...)
instead of
select * from child where parentid in (criteria query which used to select parent)
subselect fetching ignores max results
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Key: HHH-2666
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2666
Project: Hibernate ORM
Issue Type: Improvement
Components: query-hql, query-sql
Affects Versions: 3.2.1, 3.5.3
Environment: Hibernate 3.2.1
HSQLDB 8.0
Reporter: James Roper
Priority: Minor
Attachments: TestHibernateSubselect.java
When maxResults is set for a query, the hibernate subselect fetching strategy ignores it.
For example, I have a class entry, that has a list of comments, which are configured to
use the subselect fetching strategy. You can see that in the original query, only the top
? results are fetched:
select
top ? entry0_.id as id0_,
entry0_.title as title0_,
entry0_.entry as entry0_,
entry0_.time as time0_,
entry0_.category_id as category5_0_
from
Entry entry0_
order by
entry0_.time desc
But then when it does the sub select query to lazily load the comments, this is the query
it runs:
select
comments0_.entry_id as entry5_1_,
comments0_.id as id1_,
comments0_.id as id1_0_,
comments0_.time as time1_0_,
comments0_.comment as comment1_0_,
comments0_.author as author1_0_
from
Comment comments0_
where
comments0_.entry_id in (
select
entry0_.id
from
Entry entry0_
)
order by
comments0_.time desc
So, it loads every single comment in the database, even though only the comments for the
top ? entries are needed. Of course, if there was no order by clause on the first query,
the sub select may not return the same results, so it should probably only do this when
there is an order by clause in the first query, and it should make sure it includes the
order by clause in the sub select.
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