To enhance performance on a report containing time series (year ago) values, we want to create an aggregate for the fact table that is used in the report. This aggregate will be added as source to the logical fact table in the OBI Administration Tool (of OBIEE 10g). Currently this table contains a logical column DENETBG_YAGO which has as formula "AGO(DENETBG, year, 1)". The aggregate however contains a column 'DENETBG_Y1' which already contains the DENETBG value for 1 year before. Is it possible, and if so how, to add this column as source to the DENETBG_AGO logical column? I can't figure out how to mix the logical AGO-function and the fysical column in one logical column.