Design issue

chandra.shekher · **Posted:** Tue May 22, 2007 2:43 am

Hi Everybody,

I have one question...

Suppose i have such a query that brings data on the based of 4 or 5 clasess.
some of the tables have huge data around 4 to 5 lacs.

When Application runs the hibenate query. it loads all entity classes and respective data and stores it in memory.. so this way, our application server gets the heap memory error becuse all data is stores in memory.

what i feel there would be some design problem from my side...
so i want your precious advice in this context

regards
chandra
infoaxon technology

adamgibbons · **Joined:** Sat Apr 21, 2007 11:01 pm **Posts:** 144

Select only the data you need into a simple VO using "select new", you can pick and choose which colums you want to go into the VO.
Here's an example:

Code:

    @SuppressWarnings("unchecked")
    public List<AdvancedSearchSitesResultsVO> findResultsVOListBySiteBucket(int siteBucketId){
       String hql = "select new " + AdvancedSearchSitesResultsVO.class.getName() + "(\n"
                  + "    sbs.site.siteId,\n"
                  + "    sbs.site.siteRef,\n"
                  + "    sbs.site.siteName,\n"
                  + "    sbs.site.siteAdd1,\n"
                  + "    sbs.site.siteGroup.sgDesc,\n"
                  + "    sbs.site.tenancyType.tenancyType\n"
                  + ")"
                  + "from " + SiteBucketSite.class.getName() + " as sbs\n"
                  + "where sbs.siteBucket.id = " + siteBucketId;
       return (List<AdvancedSearchSitesResultsVO>)getHibernateTemplate().find(hql);
    }

the VO:

Code:

   public AdvancedSearchSitesResultsVO(
      Integer siteId, 
      String siteRef, 
      String siteName, 
      String addr1, 
      String siteGroup, 
      String usageType
   ){
      this.siteId = siteId;
      this.siteRef = siteRef;
      this.siteName = siteName;
      this.addr1 = addr1;
      this.siteGroup = siteGroup;
      this.usageType = usageType;
   }

kochcp · **Posted:** Tue May 22, 2007 9:23 am

expanding on what he said, only load the collections that you need when you need them. lazy="true" on all the relationships. and load them only when you need to display them.