[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-7175) Possible problem with org.hibernate.engine.query.HQLQueryPlan

[Imrich Olha (JIRA)]

    [ https://hibernate.onjira.com/browse/HHH-7175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=45984#comment-45984 ] 

Imrich Olha commented on HHH-7175:
----------------------------------

My suggestion for correction (shown on my simplified example):

int includedCount = -1;
for ( int x = 0; x < size; x++ ) {
final Object result = tmp.get( x );
includedCount++;
if ( max >= 0 && includedCount {color:red}>={color} max ) { // break the outer loop !!! break translator_loop; }
{color:red}combinedResults.add( result );{color}
}

> Possible problem with org.hibernate.engine.query.HQLQueryPlan
> -------------------------------------------------------------
>
>                 Key: HHH-7175
>                 URL: https://hibernate.onjira.com/browse/HHH-7175
>             Project: Hibernate ORM
>          Issue Type: Bug
>          Components: core
>         Environment: hibernate-core-3.3.2.GA.jar, Oracle DB, Java(TM) SE Runtime Environment (build 1.6.0_31-b04)
>            Reporter: Imrich Olha
>            Priority: Minor
>
> I wrote a simple 'polymorphic' queryString for org.hibernate.Query based on interface implemented by three other classes.
> I set restriction on size (maxRows) too.
> But when I executed that query, I found that some records where missing in returned list.
> I debugged sources and found possible issue in org.hibernate.engine.query.HQLQueryPlan in method 
> public List performList(QueryParameters queryParameters, SessionImplementor session) throws HibernateException { ... }
> specifically in branch for restricted (needsLimit) polymorphic query executing:
> **************************************************************************************
> int includedCount = -1;
> translator_loop: for ( int i = 0; i < translators.length; i++ ) {
> 	List tmp = translators[i].list( session, queryParametersToUse );
> 	if ( needsLimit ) {
> 		// NOTE : firstRow is zero-based
> 		int first = queryParameters.getRowSelection().getFirstRow() == null
> 		            ? 0
> 	                : queryParameters.getRowSelection().getFirstRow().intValue();
> 		int max = queryParameters.getRowSelection().getMaxRows() == null
> 		            ? -1
> 	                : queryParameters.getRowSelection().getMaxRows().intValue();
> 		final int size = tmp.size();
> 		for ( int x = 0; x < size; x++ ) {
> 			final Object result = tmp.get( x );
> 			if ( ! distinction.add( result ) ) {
> 				continue;
> 			}
> 			includedCount++;
> 			if ( includedCount < first ) {
> 				continue;
> 			}
> 			combinedResults.add( result );
> 			if ( max >= 0 && includedCount > max ) {
> 				// break the outer loop !!!
> 				break translator_loop;
> 			}
> 		}
> 	}
> 	else {
> 		combinedResults.addAll( tmp );
> 	}
> }
> **************************************************************************************
> or when I simplyfy the issue :
> int includedCount = -1;
> for ( int x = 0; x < size; x++ ) {
> 	final Object result = tmp.get( x );
> 	includedCount++;
> 	combinedResults.add( result );
> 	if ( max >= 0 && includedCount > max ) {
> 		// break the outer loop !!!
> 		break translator_loop;
> 	}
> }
> for example let start with max = 1;
> before for we start with   includedCount = -1; x is undefined; combinedResults is empty;
> after 1. iteration: includedCount = 0; x = 0; combinedResults contains 1 item;  test 'if ( max >= 0 && includedCount > max )' allows another iteration. 
> after 2. iteration: includedCount = 1; x = 1; combinedResults contains 2 items; test 'if ( max >= 0 && includedCount > max )' allows another iteration.
> after 3. iteration: includedCount = 2; x = 2; combinedResults contains 3 items; test 'if ( max >= 0 && includedCount > max )' BREAKS another iteration.
> so we will finished with 3 items in combinedResults list, but requires only max = 1;
> **************************************************************************************
> And this is (I suppose) my problem of missing records (in next iteration in our PagedDataSource) :)
> It is correct ?
> Imrich Olha
> Ps. Sorry my bad english :(

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