A user-defined function (UDF) is a powerful database fea-
ture that allows users to customize database functional-
ity. Though useful, present UDFs have numerous limita-
tions, including install-time specification of input and out-
put schema and poor ability to parallelize execution. We
present a new approach to implementing a UDF, which we
call SQL/MapReduce (SQL/MR), that overcomes many of
these limitations. We leverage ideas from the MapReduce
programming paradigm to provide users with a straightfor-
ward API through which they can implement a UDF in