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A comment on View Counting at Reddit. Parent comment

Re:View Counting at Reddit by sethammons on Saturday May 27, 2017 @10:42PM (#14432892)
I'm not following your solution for how it handles the unique visitor counting. You have to know when to increment the counter. Thus why they used the HLL.
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Re:View Counting at Reddit by diziet on Monday May 29, 2017 @02:30AM (#14437714)
Ah, sorry if it wasn't clear. By storing an expiring list post IDs in the close cache for loading the user metadata, you could filter out the posts that were already visited by that user.
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