GAIA will obtain, in a five-year mission, astrometric, photometricand spectroscopic data for more than a billion stars. The treatment ofthis huge amount of data is a challenge for the astronomicalcommunity, not only due to the database size, but also to the complexrelationships existing between the different sets of data and with theinstrumental and orbital parameters. The GAIA Data Analysis Study(GDAAS), under ESA's contract, aims to prove the feasibility of thedata reduction scheme and to implement and test a prototype of such alarge database. We present the main aspects that GDAAS addresses andreview its present status.