Bug 139346 Using isTopN in table inside list group header doesn't work.
Description: Using isTopN in table inside list group header doesn't work. Steps to reproduce: 1.Insert a list with a group 2.Insert a table to list group header 3.Using Total.isTopN(row[],2,null,0) as filter expression in table item. 4.Preview Result: Only the first group displayed top 2 records, other groups kept display all records.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
odiQuery = createOdiQuery( );
		odiQuery.setDistinctValueFlag( dataSet.needDistinctValue( ) );
		odiQuery.setExprProcessor( exprProcessor );
		populateOdiQuery( );
		prepareOdiQuery( );
		isPrepared = true;
	}
	
	/**
	 * Open the required DataSource. This method should be called after
	 * "dataSource" is initialized by findDataSource() method.
	 * 
	 * @throws DataException
	 */
	protected void openDataSource( ) throws DataException
	{
		assert odiDataSource == null;
		
		
	    
		if ( dataSource != null  )
		{
			
			if ( !dataSource.isOpen( )
					|| DataSetCacheManager.getInstance( ).doesLoadFromCache( ) == true )
			{
				
				
				
				dataSource.beforeOpen();