[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2207) Suggested fix for HQL - MySQL setMaxResults issue

[Max Rydahl Andersen (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2207?page=comments#action_25162 ] 

Max Rydahl Andersen commented on HHH-2207:
------------------------------------------

? your problem is in hibernate core, not hibernate ext (tools, annotations, etc.)

> Suggested fix for HQL - MySQL setMaxResults issue
> -------------------------------------------------
>
>          Key: HHH-2207
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2207
>      Project: Hibernate3
>         Type: Bug

>   Components: query-hql
>     Versions: 3.2.0.ga
>  Environment: Hi 3.2.0.ga MySQL
>     Reporter: Toby Moore
>  Attachments: querloaderdiff.patch
>
> Original Estimate: 0 minutes
>         Remaining: 0 minutes
>
> Hi,
> After some experimentation, we'd like to suggest an easy fix to a problem we encountered.
> When using HQL with the Hibernate 3 entity manager to limit the number of records returned ( at the database level, via generated SQL, not in memory) we were getting an exception due to the query builder trying to attach a parameter to the prepared statement that was out of bounds :
> by: java.sql.SQLException: Parameter index out of range (4 > number of parameters, which is 3).
>    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:910)
>    at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:2556)
>    at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:2584)
>    at com.mysql.jdbc.PreparedStatement.setInt(PreparedStatement.java:2540)
>    at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.setInt(NewProxyPreparedStatement.java:677)
>    at org.hibernate.loader.Loader.bindLimitParameters(Loader.java:1616)
>    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1560)
>    at org.hibernate.loader.Loader.doQuery(Loader.java:661)
>    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
>    at org.hibernate.loader.Loader.doList(Loader.java:2156)
>    ... 10 more
> On looking at the code in the method bindParameterValues in org.hibernate.loader.hql.QueryLoader ( line 491 ) the method returns the next parameter position that needs to be set, not the amount of parameters it has added, which is expected in Loader.java on the line
>          col += bindParameterValues( st, queryParameters, col, session );
> This causes the parameter count to get out of sync and thus throw the expcetion saying that it can't add a parameter out of range.
> A simple fix for this is to change the return line in QueryLoader to be
> return position - startPosition;
> which will return the amount of parameters this method added.
> We've tested this on our mysql implementation and it works, and run the unit tests to check that no extra errors are generated. If this seems like a good fix then i'll submit it as a patch via the JIRA, but would like to hear any thoughts first?
> Kind regards,
> TobyM - MindCandyDesign London

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