Alex Wood (
https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=712020%...
) *updated* an issue
Hibernate ORM (
https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiOTQzOWI1YTI3...
) / Bug (
https://hibernate.atlassian.net/browse/HHH-17040?atlOrigin=eyJpIjoiOTQzOW...
) HHH-17040 (
https://hibernate.atlassian.net/browse/HHH-17040?atlOrigin=eyJpIjoiOTQzOW...
) Hibernate can return duplicate records on join depending on row ordering (
https://hibernate.atlassian.net/browse/HHH-17040?atlOrigin=eyJpIjoiOTQzOW...
)
Change By: 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.
Unit test is available at
[
https://github.com/hibernate/hibernate-test-case-templates/pull/301|https...]
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