1. A computer-implemented method, comprising: receiving a query for which one or more indexes are to be recommended, the query including one or more expressions; identifying an expression in the query; generating a set of column statistics related to the expression; identifying one or more candidate function-based indexes associated with the query based, at least in part, on the set of column statistics; generating a set of function-based index statistics related to the one or more candidate function-based indexes; and recommending a candidate function-based index based, at least in part, on the set of function-based index statistics.