Develop Reference

Hibernate NamedQuery UPDATE statement throws QuerySyntaxException

I encountered a very interesting issue. I want to create an UPDATE statement NamedQuery for my class (I know this is a bit hacky).
The weird thing is if I use positioned parameters in the query like ?1, ?2 etc. it works perfectly. However, if I want to use named parameters like :id, it fails with the following error:
failed because of: org.hibernate.hql.internal.ast.QuerySyntaxException: expecting EOF, found 'consumingTxId' near line 1.
I'm using Kotlin btw.
My entity:
class StateDetailEntity(
#Id
#Column(name = "issue_tx_id")
val issueTxId: String,
#Column(name = "consuming_tx_id")
val consumingTxId: String?
)
My named query:
NamedQuery(
name = "StateDetailEntity.consume",
query = "UPDATE StateDetailEntity SET " +
"consumingTxId = :consumingTxId " +
"WHERE issueTxId = :issueTxId " +
"AND consumingTxId IS NULL"
)
If I add an alias to the table and re-write the name query to like UPDATE StateDetailEntity s SET... I get the following error:
org.hibernate.hql.internal.ast.QuerySyntaxException: expecting EOF, found 's'.
The funny thing is if I change the query like this:
NamedQuery(
name = "StateDetailEntity.consume",
query = "UPDATE StateDetailEntity SET " +
"consumingTxId = ?1 " +
"WHERE issueTxId = ?2 " +
"AND consumingTxId IS NULL"
)
There are no issues at all. Any ideas? Using Hibernate 5.4.32.Final.

How can I solve memory error in Hibernate Jpa? [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.

Filter rows in DataSet using JPA/Hibernate

I have the following code which is used to retrieve data from multiple tables (using joins) and then mapping every row into a DTOList but I also need to apply filters based on user preferences: per table1.name or table2.name, table3, etc.
So I just want to know what would be the best way to do it in terms of performance and best practices;
retrieving all rows and then apply the filters with lambdas (easier)
change the query to a dynamic query with Criteria or something else?
Any other solution=?
#Repository
public class ArchiveRepository {
#Autowired
EntityManager em;
String queryStr = "select wsr.id as sampleid, s.id as slideid, tb.name as batchname, k.lot_number as kitlot, " +
" 'STRING' as slidetype, tb.worklist_name as worklist, wsr.final_call as results, " +
" wa.final_pattern_ids as patterns, 'edited/yesno' as edited, wsr.last_modified_by as user, wsr.last_modified_date as time " +
" from slide s " +
" left join table2 tb on s.test_batch_id = tb.id " +
" left join table3 k on tb.kit_lot_id = k.id " +
" left join table4 w on s.id = w.slide_id " +
" left join tabl5 pw on pw.well_id = w.id " +
" left join tabl6 cw on cw.well_id = w.id " +
" left join tabl7 wsr on wsr.patient_well_sample_id = pw.id or wsr.control_sample_id = cw.id " +
" left join (select * from *** (other subselect)) wa on wa.well_sample_id = wsr.**id or wa.well_sample_id = wsr.**id " +
"where tb.state = 'STATENEEDED'";
public ArchiveDataListDTO getArchiveData(){
Query query = em.createNativeQuery(queryStr);
ArchiveDataListDTO archiveDataListDTO = new ArchiveDataListDTO();
List<Object[]> resultL = (List<Object[]>)query.getResultList();
for( Object[] o : resultL){
archiveDataListDTO.addArchiveDataRow(
new ArchiveDataDTO((String)o[0], String.valueOf(o[1]), (String) o[2], (String) o[3], (String) o[4], (String) o[5],
(String) o[6], (String) o[7], (String) o[8], (String) o[9], (String) o[10]));
}
return archiveDataListDTO;
}
}
**
note I struggled some with the code cause I wanted to apply #sqlresultsetmapping to avoid manual results mapping but it just didn´t work, most of the examples out there are when you have an entity in the DB but in this case I retrieve from many tables.**
Thanks so much

2 .- change the query to a dynamic query with Criteria or something else?

I ended up creating the query on the fly; depending on the filters I get from UI i assemble the query with Java and send it to DB, it´s easier since this required many tables...

JPA Hibernate JOIN ... ON ... AND

I use the following query:
SELECT * FROM phaseinproject as pip JOIN projectinrelease pir
ON pip.projectInRelease_id = pir.id
JOIN releaseperiod as rp ON pir.release_id = rp.id
JOIN releasestructure as rs ON rs.id = rp.releaseStructure_id
JOIN phaseinreleasestructure as pirs ON pirs.releaseStructure_id = rs.id
JOIN releasephase as rlp ON rlp.id = pirs.phase_id
AND rlp.id = pip.phase_id
This query works totally fine. I get three results (the amount I expect).
I convert this query to the following HQL query:
TypedQuery<PhaseInProjectOverview> findPhasesInRelease = em.createQuery("SELECT NEW nl.dashboard.dto.out.PhaseInProjectOverview(phaseInProject.id, phase.name, phaseInProject.startDate, phaseInProject.plannedEndDate, phaseInProject.endDate) FROM PhaseInProject phaseInProject "
+ "JOIN phaseInProject.projectInRelease projectInRelease "
+ "JOIN projectInRelease.release release "
+ "JOIN release.releaseStructure releaseStructure "
+ "JOIN releaseStructure.phaseInReleaseStructures phaseInReleaseStructure "
+ "JOIN phaseInReleaseStructure.phase phase "
+ "WHERE release.id = :releaseId ORDER BY phaseInReleaseStructure.position, phaseInProject.startDate", PhaseInProjectOverview.class);
findPhasesInRelease.setParameter("releaseId", releaseId);
return findPhasesInRelease.getResultList();
No matter what I try: I get 6 results, because HQL does not seem to support the "JOIN ... ON ... AND ..." sql syntax.
Does anyone know how to solve this problem?
edit:
I added my own answer with the used solution. Thank you all for the answers/pointers.

Try the with keyword: phaseInReleaseStructure.phase phase WITH phase.id = phaseInProject.phase_id - this should result in SQL like releasephase as rlp ON rlp.id = pirs.phase_id AND rlp.id = pip.phase_id
Alternatively just add that condition in the where clause:
... WHERE release.id = :releaseId AND phase.id = phaseInProject.phase_id ...

I solved my problem with an extra WHERE clause:
phase.id = phaseInProject.phase.id
Now I get the results I was expecting.
The 'WITH' keyword does not seem to work with multiple entities. When I try, I get an exception:
HQL error: with-clause referenced two different from-clause elements
When trying to use the 'ON' syntax like JOIN phaseInReleaseStructure.phase phase ON phase.id = phaseInProject.id, I get another error:
unexpected token: ON near line 1, column 473

How can I avoid the Warning "firstResult/maxResults specified with collection fetch; applying in memory!" when using Hibernate?

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.