Hello Simon. Tombstone is a tricky topic in Cassandra that brought a lot of questions over time. I exposed my understanding in a blog post last year and thought it might be of interest for you, even though things probably evolved a bit, principles and tuning did not change that much I guess.
Here is the post: thelastpickle.com/blog/2016/07/27/about-deletes-and-tombstones.html. 2017-12-05 2:01 GMT+00:00 wxn...@zjqunshuo.com <wxn...@zjqunshuo.com>: > Got it. Thank you. > > > *From:* Meg Mara <mm...@digitalriver.com> > *Date:* 2017-12-05 01:54 > *To:* user@cassandra.apache.org > *Subject:* RE: Tombstone warnings in log file > > Simon, > > > > It means that in processing your queries, Cassandra is going through that > many tombstone cells in order to return your results. It is because some of > the partitions that you are querying for have already expired. The warning > is just cassandra’s way of letting you know that your reads are less > efficient because you are reading a lot of expired data. > > > > You could tune this by altering your tombstone parameters in Cassandra > yaml file. But a better solution would be to reduce your GC grace seconds > for that table to a smaller value (as opposed to default of 10 days) so > that the TTLed data will be purged sooner. > > > > You could also consider drafting more efficient queries which won’t hit > TTLed partitions. > > > > Thanks, > > *Meg* > > > > > > *From:* wxn...@zjqunshuo.com [mailto:wxn...@zjqunshuo.com] > *Sent:* Sunday, December 03, 2017 7:49 PM > *To:* user <user@cassandra.apache.org> > *Subject:* Tombstone warnings in log file > > > > Hi, > > My cluster is running 2.2.8, no update and deletion, only insertion with > TTL. I saw below warnings reacently. What's the meaning of them and what's > the impact? > > > > WARN [SharedPool-Worker-2] 2017-12-04 09:32:48,833 > SliceQueryFilter.java:308 - Read 2461 live and 1978 > tombstone cells in cargts.eventdata for key: 129762:20171202 (see > tombstone_warn_threshold). 5000 columns were requested, slices=[-] > > > > Best regards, > > -Simon > > WARN [SharedPool-Worker-2] 2017-12-04 09:32:48,833 SliceQueryFilter.java:308 > - Read 2461 live and 1978 tombstone cells in cargts.eventdata f or > key: 129762:20171202 (see tombstone_warn_threshold). 5000 columns were > requested, slices=[-] > >
