Lossy Unique Count with hll

We can rewrite the query using our hll data type now, even though, at this stage, it’s not going to be very useful because we still have the full logs of every visit, and we can afford to compute precise counts.

Computing precise counts

Nonetheless, our goal is to dispose of the daily entries that we anticipate will be just too large a dataset. So, the hll-based query looks like this: