NH-3848 - Child collection fetched using left outer join with on clause or where clause restrictions on fetched collection shouldn’t be stored in second level cache.

[nhibernate-bot]

Lukasz created an issue — 22nd February 2016, 11:36:30:

Reproductions Steps:

1. Enable second level cache in nh configuration.
2. Create entity with collection.
3. Enable second level cache on collection (on collection entity also ofc).
4. Open session.
5. Create QueryOver (Criteria or HQL) which fetch root entities with children collections using left outer join with some restrictions on collection.
   E.g.

 firstSession.QueryOver<Customer>()
    .JoinAlias(n => n.Orders,
               () => ordersAlias,
               JoinType.LeftOuterJoin,
               Restrictions.Eq("Number", orderNumber))
    .List();

6. Open another session.
7. Create QueryOver on second session for all root entities. E.g.

secondSession.QueryOver<Customer>().List();

8. Iterate over entities fetched in point 7. and fetch child collections.
9. All collection fetched in point 8. Will be filtered like in point 5.

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Lukasz added a comment — 23rd February 2016, 13:08:49:

Pull request with tests and fix for Criteria and QueryOver: #460

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Lukasz added a comment — 24th February 2016, 14:01:27:

Pull request with tests and fix for HQL: #463

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Alexander Zaytsev added a comment — 7th April 2017, 1:37:44:

<~Lukasz> your pull request(s) do not consider 2 separate fetches. When there is a collection with restrictions and another one without then I expect that the collection without restrictions would be cached.

So, the property "CanAddCollectionsToCache" shall probably be a dictionary.

[fredericDelaporte]

The QueryOver and Criteria case has been separately fixed with #460, in 5.2. The HQL case remains to be fixed.

[nahumtimerman]

Hi,

LMK if I should open a new issue, I think mine is related to this one.

I have a similar issue, but the restriction is at the third level, i.e. grandchild. I'm using Nhibernate 5.5
In that case, the second level collection is cached, even though not all entities were brought (as they were filtered through the grandchild)

example:

session.QueryOver<User>
    .JoinQueryOver<Group>(x => x.Groups, JoinType.LeftOuterJoin)
    .JoinQueryOver<TestShellDomainGroup>(x => x.TestShellDomainGroups)
    .WhereRestrictionOn(x => x.Domain.Id).IsIn(domainIds).List<User>();

after making this call, user shows only a subset of groups in other calls (due to second level cache)
I look at the previous PR, and it checks if the immediate collection HasRestrictions, beforce deciding it is uncacheable.
However, couldnt restrictions on child collections cause parent collections to be considered uncacheable?