N+1 select with entities that contain Maps (even with FetchType.EAGER)
----------------------------------------------------------------------
Key: OPENJPA-1920
URL: https://issues.apache.org/jira/browse/OPENJPA-1920
Project: OpenJPA
Issue Type: Improvement
Components: kernel
Affects Versions: 2.0.0
Reporter: Vermeulen
When I have an entity that contains a Map, e.g.:
@Entity
public class TestEntity {
@ElementCollection(fetch = FetchType.EAGER)
Map<String, String> strings = new HashMap<String, String>();
}
And I select all existing entities
String query = "SELECT z FROM " +
TestEntity.class.getSimpleName()
+ " z";
List<TestEntity> result = em.createQuery(query,
TestEntity.class)
.getResultList();
n + 1 selects are performed which can be seen by using <property
name="openjpa.Log" value="DefaultLevel=TRACE" />
917 testPU TRACE [main] openjpa.Query - Executing query: SELECT z FROM
TestEntity z
918 testPU TRACE [main] openjpa.jdbc.SQL - <t 4837279, conn 6040101>
executing prepstmnt 17507279 SELECT t0.id, t0.name FROM TestEntity t0
918 testPU TRACE [main] openjpa.jdbc.SQL - <t 4837279, conn 6040101> [0 ms]
spent
919 testPU TRACE [main] openjpa.jdbc.SQLDiag - load field: 'strings' for
oid=entities.TestEntity-1 class entities.TestEntity
919 testPU TRACE [main] openjpa.jdbc.SQL - <t 4837279, conn 6040101>
executing prepstmnt 7493991 SELECT t0.KEY0, t0.value FROM TestEntity_strings t0
WHERE t0.TESTENTITY_ID = ? [params=(long) 1]
919 testPU TRACE [main] openjpa.jdbc.SQL - <t 4837279, conn 6040101> [0 ms]
spent
920 testPU TRACE [main] openjpa.jdbc.SQLDiag - load field: 'strings' for
oid=entities.TestEntity-51 class entities.TestEntity
920 testPU TRACE [main] openjpa.jdbc.SQL - <t 4837279, conn 6040101>
executing prepstmnt 7200207 SELECT t0.KEY0, t0.value FROM TestEntity_strings t0
WHERE t0.TESTENTITY_ID = ? [params=(long) 51]
etc.....
It doesn't matter whether or not I use <property
name="openjpa.jdbc.EagerFetchMode" value="parallel"/> or <property
name="openjpa.jdbc.EagerFetchMode" value="join"/>.
This is extremely inefficient when I wish to load a list of products that have
their name set in multiple languages by using a Map from language to String.
As a workaround I can turn the Map into a List and search the List myself for
the right entry.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
