Bug 180189 Support in memory data set cache.
Currently, Design-Time Data Cache is stored on disks. By performance tests using ramdisk, we found that caching in physical memory can improve the performance of RunAndRender by 30%.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedJointDataSourceQuery.java
}
			}
			if ( dataSet.getResultSetHints( ) != null )
			{
				List hintList = dataSet.getResultSetHints( );
				for ( int i = 0; i < hintList.size( ); i++ )
				{
					IColumnDefinition columnDefinition = (IColumnDefinition) hintList.get( i );
					for ( int j = 0; j < projectedColumns.size( ); j++ )
					{
						ResultFieldMetadata resultFieldMetadata = (ResultFieldMetadata) projectedColumns.get( j );
						if ( columnDefinition.getColumnName( )
								.equals( resultFieldMetadata.getName( ) ) )
						{
							resultFieldMetadata.setAlias( columnDefinition.getAlias( ) );
							break;
						}
					}
				}
			}
			ResultClass resultClass = new ResultClass( projectedColumns );
			return new JointResultMetadata( resultClass, columnSource, index );
		}
		catch ( BirtException be )
		{
			throw DataException.wrap( be );
		}
	}
	/**
	 * Return the IQueryResults