Group by ACCOUNT, then by date, process each group in turn, get the interval from first group from to the current group, and perform deduplication and counting. But SQL grouping must be accompanied by ...

APPROX_COUNT_DISTINCT( expression ) evaluates an expression for each row in a group, and returns the approximate number of unique non-null values in a group. This function is designed to provide ...

Great blog entry from Denny Lee on optmising distinct count measures here: I’d seen a ppt deck of a presentation he did at PASS a few years ago where he first set out these ideas, but it lo… ...

We consider a new type of distinct element counting problem in dynamic data streams, where (1) insertions and deletions of an element can appear not only in the same data stream but also in two or ...