[hibernate-issues] [Hibernate-JIRA] Commented: (HSEARCH-521) Improve performance MassIndexer through Eager fetching

[Marc Schipperheyn (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-521?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=36864#action_36864 ] 

Marc Schipperheyn commented on HSEARCH-521:
-------------------------------------------

After reviewing fetch profiles I was initially very enthusiastic. It seems to be the answer to some of the infuriating issues with n+1. 
However, on review it doesn't work or at least not as I would expect. Running MassIndexer on an entity

@FetchProfiles({
	@FetchProfile(name = "search", fetchOverrides = {
		@FetchProfile.FetchOverride(entity = MyClass.class, association = "foreign", mode = FetchMode.JOIN)
	})
})
@Entity
@Table
public class MyClass implements IOffer, Serializable {

a method 
@OneToOne(optional = false, cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name = "FK_ForeignID", nullable = false, updatable = false)
@IndexedEmbedded
public Foreign getForeign() {
	return foreign;
}

I see for each MyClass a separate query being executed for getForeign. This does not happen when I map getForeign as a FetchType.EAGER association.

This doesn't seem to just happen with search. I also see this behaviour on other types of hibernate core queries. Don't really understand either why there is no FetchMode for inner joins.

Anyway, this doesn't really apply to Hibernate Search other than that it doesn't look like FetchProfile works for it.

> Improve performance MassIndexer through Eager fetching
> ------------------------------------------------------
>
>                 Key: HSEARCH-521
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-521
>             Project: Hibernate Search
>          Issue Type: Improvement
>          Components: engine
>    Affects Versions: 3.2.0.CR1
>            Reporter: Marc Schipperheyn
>            Priority: Minor
>             Fix For: 3.3.0
>
>
> The MassIndexer fetches all of a certain entity from the database. It then proceeds to index it and the tree of IndexedEmbedded objects is traversed. In doing so, a lot of additional queries get executed. These queries are not really necessary, since we know beforehand that the data is needed for the indexing operation. So it would make sense to eagerly fetch all associations that are marked as indexEmbedded. This way MassIndexer would significantly speed up.

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