Is it possible to decrement a HyperLogLog set in Redis

Question

Let's say that i have a hyperloglog in redis which counts messages is there any provisions whereby I can to some degree account for delete messages?

Kunzite

Would it be reasonable to create two hyperloglog sets? messages.created and messages.deleted and just assert the decrement? – Kunzite

The two hyperloglog sets way MIGHT be a solution. It depends on your scenario. For example, it cannot solve the following scenario: add an element, delete the element, and then add the same element again. Can you give us more details on your scenario? – Norward

@Norward Yeah i mean that'd make sense. Although not sure i'd ever create the same element again - as recreating a previously deleted message would have a new UUID. – Kunzite

Another solution might be to just recreate the HLL and PFADD the entire dataset. But that becomes less and less feasible with the size of the HLL :( – Kunzite

Answer 1

No, the HyperLogLog doesn't support the concept of deletion. Instead, use a different counter (could be an integer, Set or HyperLogLog) and subtract the totals.

Ody