Bug 123915 Add table-fetch limitation when DataSet Editor is populating table names.
When fetch table names from database of large volume of data, there lies a possibility that the editor window will be frozen because of the population of huge number of table names. This should be enhanced. A handy solution might be limiting the number of table names being fetched each schema.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
/**
	 * CleanUp database connection
	 */
	private void cleanUp( )
	{
		if ( metaDataProvider != null )
		{
			metaDataProvider.closeConnection( );
		}
	}
	/**
	 * Whether should the DatabaseObjectTree should be expanded.
	 * 
	 * @param expand True if the expanding is expected. Otherwise false.
	 */
	public void setDatabaseObjectTreeExpansion( boolean expand )
	{
		this.expandDbObjectsTree = expand;
	}
	
	/**
	 * remove the tree item's direct child treeItem, cause since 3.1,
	 * TreeItem.removeAll is supported.But in 3.0,this method is not supported.
	 * 
	 * @param treeItem
	 */
	private void removeTreeItem( TreeItem treeItem )
	{
		if ( treeItem.isDisposed( ) )
			return;