Hi Jean, I am trying to solve a similar problem here. I would say that the only deterministic way is to rebuild the SStable of that column family via nodetool scrub.
Otherwise you'd need to : * decrease tombstone_threshold * wait for gc_grace_time Cheers, Stefano On Tue, May 26, 2015 at 12:51 PM, Jean Tremblay < jean.tremb...@zen-innovations.com> wrote: > I played around with these settings, namely the tombstone_threshold, and > it **eventually** triggered a Tombstone Compaction. > Now I see that getting rid of these Tombstone is a process which takes > some times. > > I would like to be able to schedule a Tombstone Compaction. > > Is there a way to trigger immediately a Tombstone Compaction on a table > which is using LeveledCompactionStrategy? > > > Thanks a lot for your help > > Jean > > On 14 May 2015, at 22:45 , Nate McCall <n...@thelastpickle.com> wrote: > > You can make LCS more aggressive with tombstone-only compactions via > seting unchecked_tombstone_compaction=true and turn down > tombstone_threshold to 0.05 (maybe going up or down as needed). Details on > both can be found here: > http://docs.datastax.com/en/cql/3.1/cql/cql_reference/compactSubprop.html > > As for monitoring tombstones, there is a "tombstoneScannedHistogram" on > ColumnFamilyMetrics which measures how many tombstones were discarded > during reads. > > Also, you should take a couple of SSTables from production and use the > sstablemetadata utility specifically looking at "Estimated droppable > tombstones" and "Estimated tombstone drop times" output from such. > > Spend some time experimenting with those settings incrementally. Finding > the sweet spot is different for each workload will make a huge difference > in overall performance. > > > > On Thu, May 14, 2015 at 8:06 AM, Jean Tremblay < > jean.tremb...@zen-innovations.com> wrote: > > > > Hi, > > > > I’m using Cassandra 2.1.4 with a table using LeveledCompactionStrategy. > > Often I need to delete many rows and I want to make sure I don’t have > too many tombstones. > > > > How does one get rid of tombstones in a table using LCS? > > How can we monitor how many tombstones are around? > > > > Thanks for your help. > > > > Jean > > > > > -- > ----------------- > Nate McCall > Austin, TX > @zznate > > Co-Founder & Sr. Technical Consultant > Apache Cassandra Consulting > http://www.thelastpickle.com > > >
