=== modified file 'dhis-2/dhis-api/src/main/java/org/hisp/dhis/organisationunit/OrganisationUnitHierarchy.java'
--- dhis-2/dhis-api/src/main/java/org/hisp/dhis/organisationunit/OrganisationUnitHierarchy.java	2011-12-26 10:07:59 +0000
+++ dhis-2/dhis-api/src/main/java/org/hisp/dhis/organisationunit/OrganisationUnitHierarchy.java	2012-04-24 12:14:22 +0000
@@ -45,6 +45,9 @@
  */
 public class OrganisationUnitHierarchy
 {
+    /**
+     * Contains mappings between parent and immediate children.
+     */
     private Map<Integer, Set<Integer>> relationships = new HashMap<Integer, Set<Integer>>();
 
     private Map<Integer, Set<Integer>> subTrees = new HashMap<Integer, Set<Integer>>();
@@ -148,7 +151,7 @@
         
         List<Integer> children = new ArrayList<Integer>();
         
-        children.add( 0, parentId );
+        children.add( 0, parentId ); // Adds parent id to beginning of list
 
         int childCounter = 1;
         
@@ -169,8 +172,10 @@
     
     public Set<Integer> getChildren( Collection<Integer> parentIds )
     {
-        Set<Integer> children = new HashSet<Integer>();
+        int capacity = parentIds.size() + 5;
         
+        Set<Integer> children = new HashSet<Integer>( Math.max( capacity, 16 ) );
+
         for ( Integer id : parentIds )
         {
             children.addAll( getChildren( id ) );
@@ -218,7 +223,9 @@
             return getChildren( parentIds );
         }
         
-        Set<Integer> children = new HashSet<Integer>();
+        int capacity = ( parentIds.size() * groups.size() ) + 5;
+        
+        Set<Integer> children = new HashSet<Integer>( Math.max( capacity, 16 ) );
         
         for ( Integer id : parentIds )
         {

=== modified file 'dhis-2/dhis-api/src/test/java/org/hisp/dhis/organisationunit/OrganisationUnitHierarchyTest.java'
--- dhis-2/dhis-api/src/test/java/org/hisp/dhis/organisationunit/OrganisationUnitHierarchyTest.java	2011-12-26 10:07:59 +0000
+++ dhis-2/dhis-api/src/test/java/org/hisp/dhis/organisationunit/OrganisationUnitHierarchyTest.java	2012-04-24 12:14:22 +0000
@@ -30,6 +30,7 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertTrue;
+import static junit.framework.Assert.assertNotNull;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -112,6 +113,35 @@
     }
     
     @Test
+    public void testGetChildren()
+    {
+        Set<Integer> parentIds = new HashSet<Integer>();
+        
+        List<OrganisationUnitRelationship> relations = new ArrayList<OrganisationUnitRelationship>();
+
+        int parentMax = 1000; // Increase to stress-test
+        int childMax = 4;
+        int childId = 0;
+        
+        for ( int parentId = 0; parentId < parentMax; parentId++ )
+        {
+            parentIds.add( parentId );
+            
+            for ( int j = 0; j < childMax; j++ )
+            {
+                relations.add( new OrganisationUnitRelationship( parentId, ++childId ) );
+            }
+        }
+        
+        OrganisationUnitHierarchy hierarchy = new OrganisationUnitHierarchy( relations );
+        
+        Set<Integer> children = hierarchy.getChildren( parentIds );
+        
+        assertNotNull( children );
+        assertEquals( ( parentMax * childMax ) + 1, children.size() );
+    }
+    
+    @Test
     public void testGetChildrenA()
     {
         List<OrganisationUnitRelationship> relationships = new ArrayList<OrganisationUnitRelationship>();

=== modified file 'dhis-2/dhis-services/dhis-service-datamart-default/src/main/java/org/hisp/dhis/datamart/engine/DefaultDataMartEngine.java'
--- dhis-2/dhis-services/dhis-service-datamart-default/src/main/java/org/hisp/dhis/datamart/engine/DefaultDataMartEngine.java	2012-04-12 12:39:47 +0000
+++ dhis-2/dhis-services/dhis-service-datamart-default/src/main/java/org/hisp/dhis/datamart/engine/DefaultDataMartEngine.java	2012-04-24 12:14:22 +0000
@@ -217,6 +217,8 @@
         organisationUnitIds = organisationUnitIds != null ? organisationUnitIds : new ArrayList<Integer>();
         organisationUnitGroupIds = organisationUnitGroupIds != null ? organisationUnitGroupIds : new ArrayList<Integer>();
         
+        clock.logTime( "Data elements: " + dataElementIds.size() + ", indicators: " + indicatorIds.size() + ", periods: " + periodIds.size() + ", org units: " + organisationUnitIds.size() );
+        
         // ---------------------------------------------------------------------
         // Get objects
         // ---------------------------------------------------------------------