[nhibernate-issues] [JIRA] Commented: (NH-1001) Select statement issued for each not-found=ignore

[NHibernate J. <nh...@gm...>]

    [ http://nhjira.koah.net/browse/NH-1001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=19007#action_19007 ] 

Tobias Johansson commented on NH-1001:
--------------------------------------

This bug is causing serious performance issues in some of our applications. Because of the extra select statements generated when an entry is not found a query that should take 10-20ms takes close to 2 seconds. 

In the description of this bug it is mentioned it affects one-to-many/many-to-many but it also affects one-to-one mappings (using References())

> Select statement issued for each not-found=ignore
> -------------------------------------------------
>
>                 Key: NH-1001
>                 URL: http://nhjira.koah.net/browse/NH-1001
>             Project:  NHibernate
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.2.0.GA
>            Reporter: Tomer Avissar
>            Priority: Minor
>         Attachments: HRNHibernateTest.zip
>
>
> When using the not-found=ignore attribute in a one-to-many/many-to-many, NHibernate is issuing a query for every element not found in the collection, even when using an outer join. 
> In some cases this causes a significant performance overhead.

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