In Hibernate 3, is there a way to do the equivalent of the following MySQL limit in HQL?
select * from a_table order by a_table_column desc limit 0, 20;
I don't want to use setMaxResults if possible. This definitely was possible in the older version of Hibernate/HQL, but it seems to have disappeared.
This was posted on the Hibernate forum a few years back when asked about why this worked in Hibernate 2 but not in Hibernate 3:
Limit was never a supported clause in HQL. You are meant to use setMaxResults().
So if it worked in Hibernate 2, it seems that was by coincidence, rather than by design. I think this was because the Hibernate 2 HQL parser would replace the bits of the query that it recognised as HQL, and leave the rest as it was, so you could sneak in some native SQL. Hibernate 3, however, has a proper AST HQL Parser, and it's a lot less forgiving.
I think Query.setMaxResults() really is your only option.
setMaxResults which would take limited number of result rows from resultset and display it to the user, in my case i have 3 million records which are queried and then am calling setMaxResults to set 50 records but i do not want to do that, while query itself i want to query for 50 records, is there a way to do that? –
Stacte setMaxResults hibernate will append the limit part to the query. It will not get all the results. You can check the query it produces by enabling: <property name="show_sql">true</property> –
Chadwell limit or top keyword, it has a rownum though, but you can't use it in combination with sorting, unless you wrap it (i.e. use subqueries). But that makes it hard to combine it with a join. MySQL and Teradata use top and requires it to be right in front of the query, but mysql requires it to be all the way at the back using the limit keyword. I have no trouble believing that MySQL and SQL Server support it, but I would be surprised if Oracle did. –
Coiffure setMaxResults() does not add limit to the query (for Oracle DB), but loads all the records in memory and does the reduction of the number of records there. When you have millions of matching records, that means an OutOfMemoryError (or related error) –
Eisenstein Hibernate-5.0.12. Is this still not available? It would be really heavy to get a million or so records and then apply the filter it- setMaxResults over it as noticed by @Rachel. –
Poock // SQL: SELECT * FROM table LIMIT start, maxRows;
Query q = session.createQuery("FROM table");
q.setFirstResult(start);
q.setMaxResults(maxRows);
setFirstResult is actually mentioned in this answer whereas here and elsewhere they just say setMaxResults this and setMaxResults that without mentioning how to set the offset. –
Correa If you don't want to use setMaxResults() on the Query object then you could always revert back to using normal SQL.
setFirstResult and setMaxResults Query methodsFor a JPA and Hibernate Query, the setFirstResult method is the equivalent of OFFSET, and the setMaxResults method is the equivalent of LIMIT:
List<Post> posts = entityManager.createQuery("""
select p
from Post p
order by p.createdOn
""")
.setFirstResult(10)
.setMaxResults(10)
.getResultList();
LimitHandler abstractionThe Hibernate LimitHandler defines the database-specific pagination logic, and as illustrated by the following diagram, Hibernate supports many database-specific pagination options:
Now, depending on the underlying relational database system you are using, the above JPQL query will use the proper pagination syntax.
SELECT p.id AS id1_0_,
p.created_on AS created_2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
LIMIT ?, ?
SELECT p.id AS id1_0_,
p.created_on AS created_2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
LIMIT ?
OFFSET ?
SELECT p.id AS id1_0_,
p.created_on AS created_on2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
OFFSET ? ROWS
FETCH NEXT ? ROWS ONLY
SELECT *
FROM (
SELECT
row_.*, rownum rownum_
FROM (
SELECT
p.id AS id1_0_,
p.created_on AS created_on2_0_,
p.title AS title3_0_
FROM post p
ORDER BY p.created_on
) row_
WHERE rownum <= ?
)
WHERE rownum_ > ?
The advantage of using setFirstResult and setMaxResults is that Hibernate can generate the database-specific pagination syntax for any supported relational databases.
And, you are not limited to JPQL queries only. You can use the setFirstResult and setMaxResults method seven for native SQL queries.
You don't have to hardcode the database-specific pagination when using native SQL queries. Hibernate can add that to your queries.
So, if you're executing this SQL query on PostgreSQL:
List<Tuple> posts = entityManager.createNativeQuery(
SELECT
p.id AS id,
p.title AS title
from post p
ORDER BY p.created_on
""", Tuple.class)
.setFirstResult(10)
.setMaxResults(10)
.getResultList();
Hibernate will transform it as follows:
SELECT p.id AS id,
p.title AS title
FROM post p
ORDER BY p.created_on
LIMIT ?
OFFSET ?
Cool, right?
Pagination is good when you can index the filtering and sorting criteria. If your pagination requirements imply dynamic filtering, it's a much better approach to use an inverted-index solution, like ElasticSearch.
You can easily use pagination for this.
@QueryHints({ @QueryHint(name = "org.hibernate.cacheable", value = "true") })
@Query("select * from a_table order by a_table_column desc")
List<String> getStringValue(Pageable pageable);
you have to pass new PageRequest(0, 1)to fetch records and from the list fetch the first record.
Pageable as a parameter in the method and calling it sending "new PageRequest(0, 20)" I'm getting the first 20 records. Thanks. –
Electromechanical Pageable class from (probably) Spring Data. It internally maps again to setFirstResult and setMaxResults. –
Phosphate If you don't want to use setMaxResults, you can also use Query.scroll instead of list, and fetch the rows you desire. Useful for paging for instance.
setMaxResults() loads first every record in memory and then creates a sublist, which when there are hundred thousands or more records crashes the server, because it is out of memory. I could however go from a JPA typed query to a Hibernate query through QueryImpl hibernateQuery = query.unwrap(QueryImpl.class) and then I could use the scroll() method as you suggested. –
Eisenstein setMaxResults(). –
Eisenstein You need to write a native query, refer this.
@Query(value =
"SELECT * FROM user_metric UM WHERE UM.user_id = :userId AND UM.metric_id = :metricId LIMIT :limit", nativeQuery = true)
List<UserMetricValue> findTopNByUserIdAndMetricId(
@Param("userId") String userId, @Param("metricId") Long metricId,
@Param("limit") int limit);
String hql = "select userName from AccountInfo order by points desc 5";
This worked for me without using setmaxResults();
Just provide the max value in the last (in this case 5) without using the keyword limit.
:P
Starting with Hibernate 6.0, HQL directly supports both [OFFSET x] LIMIT y and [OFFSET x ROWS] FETCH FIRST/NEXT y ROWS ONLY/WITH TIES, so you can e.g. do:
select e from SomeEntity e
offset 10 rows fetch next 20 rows only
JakartaEE has an open issue to also add it to the JPQL specification, but currently no-one is championing it.
My observation is that even you have limit in the HQL (hibernate 3.x), it will be either causing parsing error or just ignored. (if you have order by + desc/asc before limit, it will be ignored, if you don't have desc/asc before limit, it will cause parsing error)
If can manage a limit in this mode
public List<ExampleModel> listExampleModel() {
return listExampleModel(null, null);
}
public List<ExampleModel> listExampleModel(Integer first, Integer count) {
Query tmp = getSession().createQuery("from ExampleModel");
if (first != null)
tmp.setFirstResult(first);
if (count != null)
tmp.setMaxResults(count);
return (List<ExampleModel>)tmp.list();
}
This is a really simple code to handle a limit or a list.
Criteria criteria=curdSession.createCriteria(DTOCLASS.class).addOrder(Order.desc("feild_name"));
criteria.setMaxResults(3);
List<DTOCLASS> users = (List<DTOCLASS>) criteria.list();
for (DTOCLASS user : users) {
System.out.println(user.getStart());
}
You can use below query
NativeQuery<Object[]> query = session.createNativeQuery("select * from employee limit ?");
query.setparameter(1,1);
Below snippet is used to perform limit query using HQL.
Query query = session.createQuery("....");
query.setFirstResult(startPosition);
query.setMaxResults(maxRows);
You can get demo application at this link.
@Query(nativeQuery = true,
value = "select from otp u where u.email =:email order by u.dateTime desc limit 1")
public List<otp> findOtp(@Param("email") String email);
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Hibernate-5.0.12. Is this still not available? It would be really heavy to get a million or so records and then apply the filter on it-setMaxResultsover it as noticed by @Rachel in the answer by @skaffman. – Poock