Hibernate Batch Fetching to Lazy Loading

Question

Currently, I observe in hbernate3, the following behavior. if I have @BatchSize(size=5) set, then hibernate will fetch 5 subsets of the mapped type in one SQL query.

If I have .setFetchMode( "set", FetchMode.JOIN ); , then hibernate will eagerly fetch all the subsets of the mapped type ina single SQL query.

However, when I set .setFetchMode( "commands", FetchMode.SELECT ); , then hibernate still uses batch fetching, and not lazy fetching.

Is there a way to force hibernate to use lazy fetching when @BatchSize is set?

The same question applies to when @Fetch(FetchMode.SUBSELECT) is set.

user18943 · Accepted Answer · 2011-06-17 10:23:07Z

7

+50

If you want to override these settings programmatically, you can consider using @FetchProfile. Just create a @FetchProfile for an entity:

@FetchProfiles({
  @FetchProfile(name = "profileName", fetchOverrides = {
    @FetchProfile.FetchOverride(entity = YourEntity.class, 
                                association = "anAssociation", 
                                mode = FetchMode.JOIN),
...

    })
})

and enable that profile in your service/repository method like:

session.enableFetchProfile( "profileName" );

and your customized fetch settings will work for that session.

answered Jun 17, 2011 at 10:23

user18943

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2 Comments

iliaden Over a year ago

that sounds like what I'm looking for. Can I enable/disable this profile between two transaction within a single session?

user18943 Over a year ago

@iliaden Yes you can use Session#disableFetchProfile( profileName ) to disable that in the same session. You can also use Session#isFetchProfileEnabled( profileName ) to find out if a fetch profile is enabled or disabled.

alex.b · Accepted Answer · 2011-06-16 20:41:49Z

0

Sorry, but @BatchSize is used to solve "N+1 problem" but not to ask Hibernate load entities eagerly or lazy. Try to search by keywords: "Hibernate, n+1 problem, batch size".

answered Jun 16, 2011 at 20:41

alex.b

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1 Comment

iliaden Over a year ago

I'm aware that it helps resolving the N+1 problem. However, it overwrites the eager/lazy settings. My question is whether it is possible or not ofr these settings to co-exist and be set programmatically.

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