Alex Wood (
https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=712020%...
) *created* an issue
Hibernate ORM (
https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiYjVlOWY3YWIz...
) / Bug (
https://hibernate.atlassian.net/browse/HHH-17040?atlOrigin=eyJpIjoiYjVlOW...
) HHH-17040 (
https://hibernate.atlassian.net/browse/HHH-17040?atlOrigin=eyJpIjoiYjVlOW...
) Hibernate can return duplicate records on join depending on row ordering (
https://hibernate.atlassian.net/browse/HHH-17040?atlOrigin=eyJpIjoiYjVlOW...
)
Issue Type: Bug Affects Versions: 6.2.7 Assignee: Unassigned Created: 07/Aug/2023 07:43 AM
Environment: openjdk 17.0.7 2023-04-18
Priority: Major Reporter: Alex Wood (
https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=712020%...
)
We have a query that is fetching a grandchild collection via outer join. There should only
be one root object but in certain cases Hibernate can return duplicate root objects. The
cause of the inconsistency seems to be the ordering of the rows in the results. If all the
rows for the root object are grouped together (via an “order by” clause) for example, only
one root is returned. If the rows are disordered, duplicates are returned.
I’ve simulated the disordered results using an “order by random()” in the unit test, but
in our product environment we’ve seen rows can be returned ordered or unordered (it seems
to depend on the number of rows in the table as to whether the database decides to order
the results). I’ve included explain plans for different database behavior for the same
query as part of my pull request.
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