postmodern-p

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Partition-by

Partition-by is not table partitioning. Rather it is a clause that allows you to set the range of records that will be used for each group within an over clause. Consider it a windowing function. Partition-by is available in Postmodern as of the Oct 29, 2013 git version.

Important: Note use of :order-by without being the function call at the beginning of a form.

(query (:select 'depname 'empno 'salary

                (:over (:avg 'salary)

                       (:partition-by 'depname))

                :from 'empsalary))

(query (:select 'depname 'empno 'salary

                (:over (:rank)

                       (:partition-by 'depname :order-by (:desc 'salary)))

                :from 'empsalary))