Aim of the paper is to investigate the role of large databases in social research, with particular reference to the educational field. In the text, following the theoretical tracks of the social construction of knowledge and the Science and Technology Studies (STS), is investigated how the big data - the datasets produced by the international survey with the support of information infrastructure and multidisciplinary expert knowledge - are changing the cultural and educational policies at national and international level, producing the phenomenon of datafication of education. The OECD-PISA survey (Programme for International Student Assessment) is presented in the article as an emblematic case of the emergence of such processes.