Sure. I'm making another change for cross multiple DC replication, once this one is done (probably in next week) I'll submit them together to Jira. All based on 0.6 beta2.
-Weijun -----Original Message----- From: Jonathan Ellis [mailto:jbel...@gmail.com] Sent: Saturday, March 13, 2010 5:36 AM To: cassandra-user@incubator.apache.org Subject: Re: question about deleting from cassandra You should submit your minor change to jira for others who might want to try it. On Sat, Mar 13, 2010 at 3:18 AM, Weijun Li <weiju...@gmail.com> wrote: > Tried Sylvain's feature in 0.6 beta2 (need minor change) and it worked > perfectly. Without this feature, as far as you have high volume new and > expired columns your life will be miserable :-) > > Thanks for great job Sylvain!! > > -Weijun > > On Fri, Mar 12, 2010 at 12:27 AM, Sylvain Lebresne <sylv...@yakaz.com> > wrote: >> >> I guess you can also vote for this ticket : >> https://issues.apache.org/jira/browse/CASSANDRA-699 :) >> >> </advertising> >> >> -- >> Sylvain >> >> >> On Fri, Mar 12, 2010 at 8:28 AM, Mark Robson <mar...@gmail.com> wrote: >> > On 12 March 2010 03:34, Bill Au <bill.w...@gmail.com> wrote: >> >> >> >> Let take Twitter as an example. All the tweets are timestamped. I >> >> want >> >> to keep only a month's worth of tweets for each user. The number of >> >> tweets >> >> that fit within this one month window varies from user to user. What >> >> is the >> >> best way to accomplish this? >> > >> > This is the "expiry" problem that has been discussed on this list >> > before. As >> > far as I can see there are no easy ways to do it with 0.5 >> > >> > If you use the ordered partitioner and make the first part of the keys a >> > timestamp (or part of it) then you can get the keys and delete them. >> > >> > However, these deletes will be quite inefficient, currently each row >> > must be >> > deleted individually (there was a patch to range delete kicking around, >> > I >> > don't know if it's accepted yet) >> > >> > But even if range delete is implemented, it's still quite inefficient >> > and >> > not really what you want, and doesn't work with the RandomPartitioner >> > >> > If you have some metadata to say who tweeted within a given period (say >> > 10 >> > days or 30 days) and you store the tweets all in the same key per user >> > per >> > period (say with one column per tweet, or use supercolumns), then you >> > can >> > just delete one key per user per period. >> > >> > One of the problems with using a time-based key with ordered partitioner >> > is >> > that you're always going to have a data imbalance, so you may want to >> > try >> > hashing *part* of the key (The first part) so you can still range scan >> > the >> > next part. This may fix load balancing while still enabling you to use >> > range >> > scans to do data expiry. >> > >> > e.g. your key is >> > >> > Hash of day number + user id + timestamp >> > >> > Then you can range scan the entire day's tweets to expire them, and >> > range >> > scan a given user's tweets for a given day efficiently (and doing this >> > for >> > 30 days is just 30 range scans) >> > >> > Putting a hash in there fixes load balancing with OPP. >> > >> > Mark >> > > >
