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Avoiding "HHH000104: firstResult/maxResults specified with collection fetch; applying in memory!" using Spring Data [duplicate]

I'm getting a warning in the Server log "firstResult/maxResults specified with collection fetch; applying in memory!". However everything working fine. But I don't want this warning.
My code is
public employee find(int id) {
return (employee) getEntityManager().createQuery(QUERY).setParameter("id", id).getSingleResult();
}
My query is
QUERY = "from employee as emp left join fetch emp.salary left join fetch emp.department where emp.id = :id"

Although you are getting valid results, the SQL query fetches all data and it's not as efficient as it should.
So, you have two options.
Fixing the issue with two SQL queries that can fetch entities in read-write mode
The easiest way to fix this issue is to execute two queries:
. The first query will fetch the root entity identifiers matching the provided filtering criteria.
. The second query will use the previously extracted root entity identifiers to fetch the parent and the child entities.
This approach is very easy to implement and looks as follows:
List<Long> postIds = entityManager
.createQuery(
"select p.id " +
"from Post p " +
"where p.title like :titlePattern " +
"order by p.createdOn", Long.class)
.setParameter(
"titlePattern",
"High-Performance Java Persistence %"
)
.setMaxResults(5)
.getResultList();
List<Post> posts = entityManager
.createQuery(
"select distinct p " +
"from Post p " +
"left join fetch p.comments " +
"where p.id in (:postIds) " +
"order by p.createdOn", Post.class)
.setParameter("postIds", postIds)
.setHint(
"hibernate.query.passDistinctThrough",
false
)
.getResultList();
Fixing the issue with one SQL query that can only fetch entities in read-only mode
The second approach is to use SDENSE_RANK over the result set of parent and child entities that match our filtering criteria and restrict the output for the first N post entries only.
The SQL query can look as follows:
#NamedNativeQuery(
name = "PostWithCommentByRank",
query =
"SELECT * " +
"FROM ( " +
" SELECT *, dense_rank() OVER (ORDER BY \"p.created_on\", \"p.id\") rank " +
" FROM ( " +
" SELECT p.id AS \"p.id\", " +
" p.created_on AS \"p.created_on\", " +
" p.title AS \"p.title\", " +
" pc.id as \"pc.id\", " +
" pc.created_on AS \"pc.created_on\", " +
" pc.review AS \"pc.review\", " +
" pc.post_id AS \"pc.post_id\" " +
" FROM post p " +
" LEFT JOIN post_comment pc ON p.id = pc.post_id " +
" WHERE p.title LIKE :titlePattern " +
" ORDER BY p.created_on " +
" ) p_pc " +
") p_pc_r " +
"WHERE p_pc_r.rank <= :rank ",
resultSetMapping = "PostWithCommentByRankMapping"
)
#SqlResultSetMapping(
name = "PostWithCommentByRankMapping",
entities = {
#EntityResult(
entityClass = Post.class,
fields = {
#FieldResult(name = "id", column = "p.id"),
#FieldResult(name = "createdOn", column = "p.created_on"),
#FieldResult(name = "title", column = "p.title"),
}
),
#EntityResult(
entityClass = PostComment.class,
fields = {
#FieldResult(name = "id", column = "pc.id"),
#FieldResult(name = "createdOn", column = "pc.created_on"),
#FieldResult(name = "review", column = "pc.review"),
#FieldResult(name = "post", column = "pc.post_id"),
}
)
}
)
The #NamedNativeQuery fetches all Post entities matching the provided title along with their associated PostComment child entities. The DENSE_RANK Window Function is used to assign the rank for each Post and PostComment joined record so that we can later filter just the amount of Post records we are interested in fetching.
The SqlResultSetMapping provides the mapping between the SQL-level column aliases and the JPA entity properties that need to be populated.
Now, we can execute the PostWithCommentByRank #NamedNativeQuery like this:
List<Post> posts = entityManager
.createNamedQuery("PostWithCommentByRank")
.setParameter(
"titlePattern",
"High-Performance Java Persistence %"
)
.setParameter(
"rank",
5
)
.unwrap(NativeQuery.class)
.setResultTransformer(
new DistinctPostResultTransformer(entityManager)
)
.getResultList();
Now, by default, a native SQL query like the PostWithCommentByRank one would fetch the Post and the PostComment in the same JDBC row, so we will end up with an Object[] containing both entities.
However, we want to transform the tabular Object[] array into a tree of parent-child entities, and for this reason, we need to use the Hibernate ResultTransformer.
The DistinctPostResultTransformer looks as follows:
public class DistinctPostResultTransformer
extends BasicTransformerAdapter {
private final EntityManager entityManager;
public DistinctPostResultTransformer(
EntityManager entityManager) {
this.entityManager = entityManager;
}
#Override
public List transformList(
List list) {
Map<Serializable, Identifiable> identifiableMap =
new LinkedHashMap<>(list.size());
for (Object entityArray : list) {
if (Object[].class.isAssignableFrom(entityArray.getClass())) {
Post post = null;
PostComment comment = null;
Object[] tuples = (Object[]) entityArray;
for (Object tuple : tuples) {
if(tuple instanceof Identifiable) {
entityManager.detach(tuple);
if (tuple instanceof Post) {
post = (Post) tuple;
}
else if (tuple instanceof PostComment) {
comment = (PostComment) tuple;
}
else {
throw new UnsupportedOperationException(
"Tuple " + tuple.getClass() + " is not supported!"
);
}
}
}
if (post != null) {
if (!identifiableMap.containsKey(post.getId())) {
identifiableMap.put(post.getId(), post);
post.setComments(new ArrayList<>());
}
if (comment != null) {
post.addComment(comment);
}
}
}
}
return new ArrayList<>(identifiableMap.values());
}
}
The DistinctPostResultTransformer must detach the entities being fetched because we are overwriting the child collection and we don’t want that to be propagated as an entity state transition:
post.setComments(new ArrayList<>());

Reason for this warning is that when fetch join is used, order in result sets is defined only by ID of selected entity (and not by join fetched).
If this sorting in memory is causing problems, do not use firsResult/maxResults with JOIN FETCH.

To avoid this WARNING you have to change the call getSingleResult to
getResultList().get(0)

This warning tells you Hibernate is performing in memory java pagination. This can cause high JVM memory consumption.
Since a developer can miss this warning, I contributed to Hibernate by adding a flag allowing to throw an exception instead of logging the warning (https://hibernate.atlassian.net/browse/HHH-9965).
The flag is hibernate.query.fail_on_pagination_over_collection_fetch.
I recommend everyone to enable it.
The flag is defined in org.hibernate.cfg.AvailableSettings :
/**
* Raises an exception when in-memory pagination over collection fetch is about to be performed.
* Disabled by default. Set to true to enable.
*
* #since 5.2.13
*/
String FAIL_ON_PAGINATION_OVER_COLLECTION_FETCH = "hibernate.query.fail_on_pagination_over_collection_fetch";

the problem is you will get cartesian product doing JOIN. The offset will cut your recordset without looking if you are still on same root identity class

I guess the emp has many departments which is a One to Many relationship. Hibernate will fetch many rows for this query with fetched department records. So the order of result set can not be decided until it has really fetch the results to the memory. So the pagination will be done in memory.
If you do not want to fetch the departments with emp, but still want to do some query based on the department, you can achieve the result with out warning (without doing ordering in the memory). For that simply you have to remove the "fetch" clause. So something like as follows:
QUERY = "from employee as emp left join emp.salary sal left join emp.department dep where emp.id = :id and dep.name = 'testing' and sal.salary > 5000 "

As others pointed out, you should generally avoid using "JOIN FETCH" and firstResult/maxResults together.
If your query requires it, you can use .stream() to eliminate warning and avoid potential OOM exception.
try (Stream<ENTITY> stream = em.createQuery(QUERY).stream()) {
ENTITY first = stream.findFirst().orElse(null); // equivalents .getSingleResult()
}
// Stream returned is an IO stream that needs to be closed manually.

Hibernate createNativeQuery - get more than one Entity

I am using following code to execute native SQL query with hibernate:
Query zonesQuery = session.createNativeQuery(
"Select * \n" +
"FROM dbo.Structure AS S\n" +
"JOIN dbo.StructureLocationType AS SLT ON SLT.StructureId = S.Id\n" +
"WHERE SLT.LocationTypeId = :lc").addEntity(StructureEntity.class);
zonesQuery.setParameter("lc", locationTypeID);
List<StructureEntity> zones = zonesQuery.list();
So it works and it gets me list of StructureEntity
now, because my sql query "join" from StructureLocationType table, is there possibility to get whole StructureLocationType row as well, still using single query?
Thank you.

It can be achieved with the following (notice curly braces in SQL and entities aliases):
Query query = session
.createNativeQuery(
"SELECT {S.*}, {SLT.*} " +
"FROM dbo.Structure AS S " +
"JOIN dbo.StructureLocationType AS SLT ON SLT.StructureId = S.Id " +
"WHERE SLT.LocationTypeId = :lc")
.unwrap(SQLQuery.class)
.addEntity("S", StructureEntity.class)
.addEntity("SLT", StructureLocationTypeEntity.class)
.setParameter("lc", locationTypeID);
List<Pair<StructureEntity, StructureLocationTypeEntity>> result = ((List<Object[]>) query.list())
.stream()
.map(p -> Pair.of((StructureEntity) p[0], (StructureLocationTypeEntity) p[1]))
.collect(Collectors.toList());

You can't get multiple Objects from one query.
But you could either select which columns you want and then iterate the returned Object array:
The query:
SELECT s.id, s.someColumn, slt.id, slt.structureId
FROM dbo.Structure AS s
JOIN dbo.StructureLocationType AS slt on slt.structureId = s.id
WHERE slt.locationTypeId = :lc
Then iterate over the Object array:
List<Object[]> result = query.getResultList();
Or you could create a view on your database and map it to a java entity using the Table annotation like it was a normal table:
#Entity
#Table(name = "STRUCTURE_LOCATION_TYPE_VIEW")
public class StructureAndLocationType {
// ...
}
I thought there is a way to map from a query to an Object without creating a DB view but couldn't find it right now.

Malformed query using IN

I have this structure:
public enum SaleItemType {
CRUISE,
DAILY_HOSTING
}
public class Estimate {
...
private List<SaleItemType> interestedSaleItemTypes;
#Column(name = "sale_item_type")
#CollectionTable(name = "estimate_sale_item_type", joinColumns = #JoinColumn(name = "estimate_id"))
#ElementCollection(targetClass = SaleItemType.class)
#Enumerated(EnumType.STRING)
public List<SaleItemType> getInterestedSaleItemTypes() {
return interestedSaleItemTypes;
}
}
And i'm trying to do a simple query:
String q = "FROM " + Estimate.class.getSimpleName() + " e" + " WHERE e.interestedSaleItemTypes IN :a";
TypedQuery<Estimate> query1 = getEm().createQuery(q, Estimate.class);
query1.setParameter("a", EnumSet.of(SaleItemType.CRUISE));
query1.getResultList();
I'm getting this query(and error) on the log:
DEBUG SQL:92 - select estimate0_.id as id1_25_, estimate0_.average_ticket as average_2_25_, estimate0_.description as descript3_25_, estimate0_.end_date as end_date4_25_, estimate0_.pax_quantity as pax_quan5_25_, estimate0_.start_date as start_da6_25_ from estimate estimate0_ cross join estimate_sale_item_type interested1_ where estimate0_.id=interested1_.estimate_id and (. in (?))
DEBUG SqlExceptionHelper:124 - could not extract ResultSet [n/a]
org.postgresql.util.PSQLException: No value specified for parameter 1.
Why hibernate is doing this query?
Im using Hibernate 5.1 Final

The IN expression can be used to test if a value is in a collection but interestedSaleItemTypes is not a simple value but itself a collection. Therefore use MEMBER OF:
String q = "FROM Estimate e WHERE :a MEMBER OF e.interestedSaleItemTypes";
TypedQuery<Estimate> query1 = getEm().createQuery(q, Estimate.class);
query1.setParameter("a", SaleItemType.CRUISE);

Did you try to put parenthesis in your IN clause?
I don't know if it's required, but in all tutorials that I found, always had the parenthesis. http://www.postgresqltutorial.com/postgresql-in/
Also, as the IN clause is expecting a list of values you can use the setParameterList instead of setParameter.
Try this:
String q = "FROM " + Estimate.class.getSimpleName() + " e" + " WHERE e.interestedSaleItemTypes IN (:a)";
TypedQuery<Estimate> query1 = getEm().createQuery(q, Estimate.class);
query1.setParameterList("a", EnumSet.of(SaleItemType.CRUISE));
query1.getResultList();

JPA: PGobject cannot be cast

I'm using JPA for the first time and I'm getting this error when I try to query the postgres database:
Exception in thread "main" java.lang.ClassCastException: org.postgresql.util.PGobject cannot be cast to [Ljava.lang.Object;
The code is:
List<Results> r = em.createNativeQuery("SELECT r FROM RESULTS r\n"
+ "INNER JOIN SESSION S ON s.SESSION_ID = r.SESSION_ID WHERE s.SESSION_ID = '" + sessionId + "'").getResultList();
I've already tried with Object[], but the error still the same
List<Object[]> r = em.createNativeQuery("SELECT r FROM RESULTS r\n"
+ "INNER JOIN SESSION S ON s.SESSION_ID = r.SESSION_ID WHERE s.SESSION_ID = '" + sessionId + "'").getResultList();
Someone knows whats wrong?

I noticed you are using JPQL syntax for a nativeQuery, have you tried this code with the createQuery method()?
List<Results> r = em.createQuery("SELECT r FROM RESULTS r\n"
+ "INNER JOIN SESSION S ON s.SESSION_ID = r.SESSION_ID WHERE s.SESSION_ID = '" + sessionId + "'").getResultList();
If the sql is correct and you are using a native query, does
Query query = em.createNativeQuery(SELECT * FROM RESULTS r\n"
+ "INNER JOIN SESSION S ON s.SESSION_ID = r.SESSION_ID WHERE s.SESSION_ID = '" + sessionId + "'");
List<Object[]> result = query.getResultList();
Return without a class cast exception?

On the assumption that you're using SQL and not JPQL then why aren't you just using this?
List<Object> result = query.getResultList();
Since you're only selecting a single column in the SQL then makes more sense for each row to map to an Object.

Error: Cannot create TypedQuery for query with more than one return

I try to do the function searchBook with java and jpa. I have 2 classes which are Media and Book. Book extends Media. And I keep the data in the different table. I try to select the data from the query below:
TypedQuery<Media> query = em.createQuery(
"SELECT m.title, b.isbn, b.authors"
+ " FROM Book b, Media m" + " WHERE b.isbn = :isbn"
+ " OR lower(m.title) LIKE :title"
+ " OR b.authors LIKE :authors", Media.class);
query.setParameter("isbn", book.getisbn());
query.setParameter("title", "%" + book.getTitle().toLowerCase()
+ "%");
query.setParameter("authors", "%" + book.getAuthors() + "%");
bookList = query.getResultList();
But I got the error:
java.lang.IllegalArgumentException: Cannot create TypedQuery for query
with more than one return
This is the first time I use JPA. I can't find the the mistake.

As a workaround, to get entity composed by other entity attributes, you can create it within query, providing constructor for it.
Query :
TypedQuery<Media> query = em.createQuery("SELECT NEW package_name.Media(m.title, b.isbn, b.authors)"
+ " FROM Book b, Media m"
+ " WHERE b.isbn = :isbn"
+ " OR lower(m.title) LIKE :title"
+ " OR b.authors LIKE :authors", Media.class);
Entity :
public Media(String title, int isbn, String author){
//-- Setting appropriate values
}
I have provided sample, change the datatypes of the constructor accordingly.

Without goind into details about how Media and Book should be modeled, I will at least explain why you get this exception.
You're doing:
em.createQuery(someJPQL, Media.class);
This means: create a query using someJPQL, and this query will return instances of the Media entity.
But your JPQL is:
SELECT m.title, b.isbn, b.authors ...
So the query does not return entities of type Media. It returns three fields, from two different entities. There is no way your JPA engine could magically create instances of Media from these 3 columns. A query would return instances of Media if it looked like this:
select m from Media m ...

If you still want to use TypedQuery you can change the result type to Object[].
List<Object[]> results = entityManager
.createQuery("SELECT m.title, b.isbn, b.authors ...", Object[].class)
.getResultList();
Each Object[] in the List represents a row of data. It contains the selected values for that row in the order in which they were selected in the query. Element 0 is the title, element 1 is the ISBN, and element 2 is the authors. You'll likely need to cast those values if you want to use them in a meaningful way. Since the field values come from two different tables, you could store them in some kind of container object.
List<MediaContainer> mediaList = new ArrayList<>();
for (Object[] row : results) {
MediaContainer container = new MediaContainer();
container.setTitle((String) row[0]);
container.setIsbn((int) row[1]);
container.setAuthors((String) row[2]);
mediaList.add(container);
}

#WebUser instead of doing
List<EntityIDKey> companies =
getEntityManager().createQuery(sql, EntityIDKey.class).getResultList();
Try this :
List<EntityIDKey> companies =
(List<EntityIDKey>)getEntityManager().createQuery(sql).getResultList();
works for me.

if your are using Hibernate version < 4, you can meet this bug.
I go same problem with v3.5. Finally i had to use simple Query and cast each parameter manually
see other comments here : https://groups.google.com/forum/#!topic/axonframework/eUd1d4rotMY

I... remove
Media.class
of
createQuery
because you return more Entities in this source "SELECT m.title, b.isbn, b.authors"
Ex.:
TypedQuery<Media> query = em.createQuery(
"SELECT m.title, b.isbn, b.authors"
+ " FROM Book b, Media m" + " WHERE b.isbn = :isbn"
+ " OR lower(m.title) LIKE :title"
+ " OR b.authors LIKE :authors");

You can resolve the issue by doing this kind of query:
em.createQuery( "SELECT m"
+ " FROM Book b, Media m" + " WHERE b.isbn = :isbn"
+ " OR lower(m.title) LIKE :title"
+ " OR b.authors LIKE :authors", Media.class);
but this works only if you need fields only from one of the requested tables