[jira] Created: (IBATIS-302) Lazy Loading performance improvement

["Oleg Shpak (JIRA)" <ib...@incubator.apache.org>]

Lazy Loading performance improvement
------------------------------------

         Key: IBATIS-302
         URL: http://issues.apache.org/jira/browse/IBATIS-302
     Project: iBatis for Java
        Type: Improvement

  Components: SQL Maps  
    Reporter: Oleg Shpak
    Priority: Minor


It is very common to use a single parameter (an object ID) to load a dependent object. This parameter is usually exposed as a property of the dependent object. It would be good if lazy loading could be configured to return this parameter as the respective property value without actually loading the object from the database.
Consider this example:

class Issue {
  public Project getProject();
...
}

  <select id="getProjectById" resultMap="result" parameterClass="java.lang.Integer">
    SELECT * FROM projects
    WHERE id=#id#
  </select>
  .....

  <resultMap id="issueResult" class="Issue">
    <result property="id" column="id"/>
    <result property="project" column="project_id" select="getProjectById"/>
    ...
  </resultmap>

issue.getProject().getId() may return without actually loading the object from the database.
I understand that some additional attributes will be needed to name the matching property of the target object.

A global iBatis settings parameter might be good to turn off this feature for some circumstances.

Thanks

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