When you say “no need for tombstones”, did you actually read that somewhere or were you just speculating? If the former, where exactly?
-- Jack Krupansky From: Ian Rose Sent: Tuesday, December 16, 2014 10:22 AM To: user Subject: does consistency=ALL for deletes obviate the need for tombstones? Howdy all, Our use of cassandra unfortunately makes use of lots of deletes. Yes, I know that C* is not well suited to this kind of workload, but that's where we are, and before I go looking for an entirely new data layer I would rather explore whether C* could be tuned to work well for us. However, deletions are never driven by users in our app - deletions always occur by backend processes to "clean up" data after it has been processed, and thus they do not need to be 100% available. So this made me think, what if I did the following? a.. gc_grace_seconds = 0, which ensures that tombstones are never created b.. replication factor = 3 c.. for writes that are inserts, consistency = QUORUM, which ensures that writes can proceed even if 1 replica is slow/down d.. for deletes, consistency = ALL, which ensures that when we delete a record it disappears entirely (no need for tombstones) e.. for reads, consistency = QUORUM Also, I should clarify that our data essentially append only, so I don't need to worry about inconsistencies created by partial updates (e.g. value gets changed on one machine but not another). Sometimes there will be duplicate writes, but I think that should be fine since the value is always identical. Any red flags with this approach? Has anyone tried it and have experiences to share? Also, I *think* that this means that I don't need to run repairs, which from an ops perspective is great. Thanks, as always, - Ian
