[hibernate-issues] [Hibernate-JIRA] Created: (HHH-3432) query.uniqueResult() potentially generates out of memory by calling list()

[Emmanuel Bernard (JIRA)]

query.uniqueResult() potentially generates out of memory by calling list()
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                 Key: HHH-3432
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3432
             Project: Hibernate3
          Issue Type: Bug
    Affects Versions: 3.3.0.CR2, 3.2.6
            Reporter: Emmanuel Bernard


calling list() while the user expects a single result has potential major flow: it's easy to trigger an out of memory situation where nobody would expect it... 
like getSingleResult("select CURRENT_TIME from AN_ENTITY_CONTAINING_ZILLIONS_OF_RECORDS") ; 

(and it is also a performance problem when it doesn't trigger the out of heap space... and a design issue: why fetching something the caller is not asking for ? with all the consequences on the cache...) 

fix:
Something like that
if (maxResults != 1) query.setMaxResults( 2 ); //avoid OOME if the list is huge
List result = query.list();
if ( maxResults != -1 ) query.setMaxResults( maxResults ); //put back the original value


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