A method and system are disclosed for use with an ETL (Extract, Transform, Load) process, comprising optimizing a filter expression to select a subset of data and evaluating the filter expression on the data after the extracting, before the loading, but not during the transforming of the ETL process. The method and system optimizes the filtering using a pipelined evaluation for single predicate filtering and an adaptive optimization for multiple predicate filtering. The adaptive optimization includes an initial phase and a dynamic phase.