Efficient sampling of a relational database

A system, method and computer readable medium for sampling data from a relational database are disclosed, where an information processing system chooses rows from a table in a relational database for sampling, wherein data values are arranged into rows, rows are arranged into pages, and pages are arranged into tables. Pages are chosen for sampling according to a probability P and rows in a selected page are chosen for sampling according to a probability R, so that the overall probability of choosing a row for sampling is Q=PR. The probabilities P and R are based on the desired precision of estimates computed from a sample, as well as processing speed. The probabilities P and R are further based on either catalog statistics of the relational database or a pilot sample of rows from the relational database.