Casandra's data files are write once. Deletes are another write. Until compaction they all live on disk.Making really big rows has these problem.
On Sat, Mar 2, 2013 at 1:42 PM, Michael Kjellman <mkjell...@barracuda.com>wrote: > What is your gc_grace set to? Sounds like as the number of tombstones > records increase your performance decreases. (Which I would expect) > > On Mar 2, 2013, at 10:28 AM, "Víctor Hugo Oliveira Molinar" < > vhmoli...@gmail.com> wrote: > > I have a daily maintenance of my cluster where I truncate this column > family. Because its data doesnt need to be kept more than a day. > Since all the regular operations on it finishes around 4 hours before > finishing the day. I regurlarly run a truncate on it followed by a repair > at the end of the day. > > And every day, when the operations are started(when are only few deleted > columns), the performance looks pretty well. > Unfortunately it is degraded along the day. > > > On Sat, Mar 2, 2013 at 2:54 PM, Michael Kjellman > <mkjell...@barracuda.com>wrote: > >> When is the last time you did a cleanup on the cf? >> >> On Mar 2, 2013, at 9:48 AM, "Víctor Hugo Oliveira Molinar" < >> vhmoli...@gmail.com> wrote: >> >> > Hello guys. >> > I'm investigating the reasons of performance degradation for my case >> scenario which follows: >> > >> > - I do have a column family which is filled of thousands of columns >> inside a unique row(varies between 10k ~ 200k). And I do have also >> thousands of rows, not much more than 15k. >> > - This rows are constantly updated. But the write-load is not that >> intensive. I estimate it as 100w/sec in the column family. >> > - Each column represents a message which is read and processed by >> another process. After reading it, the column is marked for deletion in >> order to keep it out from the next query on this row. >> > >> > Ok, so, I've been figured out that after many insertions plus deletion >> updates, my queries( column slice query ) are taking more time to be >> performed. Even if there are only few columns, lower than 100. >> > >> > So it looks like that the longer is the number of columns being >> deleted, the longer is the time spent for a query. >> > -> Internally at C*, does column slice query ranges among deleted >> columns? >> > If so, how can I mitigate the impact in my queries? Or, how can I avoid >> those deleted columns? >> >> Copy, by Barracuda, helps you store, protect, and share all your amazing >> things. Start today: www.copy.com. >> > > > ---------------------------------- > Copy, by Barracuda, helps you store, protect, and share all your amazing > things. Start today: www.copy.com <http://www.copy.com?a=em_footer>. > >
