A new algorithm is presented for managing the buffer pool of a RDBMS, DBMIN. DBMIN is based on a new model of relational query behavior, the Query Locality Set Model (QLSM). Like the Hot Set Model, the QLSM has an advantage over the stochastic models due to its ability to predict future reference behavior. However, the QLSM avoids the potential problems of the hot set model by separating the modeling of reference behavior from any particular buffer management algorithm. After introducing the QLSM and describingthe DBMIN algorithm, they present a performance evaluation methodology for evaluating buffer management algorithms in a multi-user environment. This methodology employed a hybrid model that combines features of both trace driven and distribution driven simulation models. Using this model, the performance of the DBMIN algorithm is compared with that of the Hot Set Model and four more traditional buffer replacement algorithms.