I strongly recommend avoiding tick tock. You'll be one of the only people putting it in prod and will likely hit a number of weird issues nobody will be able to help you with. On Tue, Oct 4, 2016 at 12:40 PM Benjamin Roth <benjamin.r...@jaumo.com> wrote:
> I have the impression, that not the tick-tock is the real problem but MVs > are not really battle-tested yet. > Depending on the model, they put much more complexity on a cluster and > it's behaviour under heavy load. Especially if you are going to create an > MV with a different partition key than the base table this might be a shot > in the head. > At least I was able to bring my cluster down many times just by throwing a > few queries too much at it or by running some big repairs with reaper. > Only since some days, things seem to go smoothly after having struggled > about 2 months with very different kind of issues. > > We'll see ... most probably I will stick with the latest version. After > all it seems to work ok, I gained a lot of experience in running and > troubleshooting and to deal with bugs and maybe I am so able to contribute > a bit to further development. > > 2016-10-04 18:26 GMT+02:00 Vladimir Yudovin <vla...@winguzone.com>: > > >Would you consider 3.0.x to be more stable than 3.x? > I guess yes, but there are some discussion on this list: > > (C)* stable version after 3.5 > <https://lists.apache.org/thread.html/4e4e67175efd1207965eb528e098f35dd268fba0f66632924d8bd0a2@%3Cuser.cassandra.apache.org%3E> > Upgrade from 3.0.6 to 3.7. > <https://lists.apache.org/thread.html/14e383fabe1ea1750a3e3eec78a1490ae27484ed2d3424d9c3aeb9e2@%3Cuser.cassandra.apache.org%3E> > > It seems to be eternal topic till tick-tock approach stabilizes. > > > Best regards, Vladimir Yudovin, > > > *Winguzone Inc <https://winguzone.com?from=list> - Hosted Cloud Cassandra > on Azure and SoftLayer.Launch your cluster in minutes.* > > > ---- On Tue, 04 Oct 2016 12:19:13 -0400 *Benjamin > Roth<benjamin.r...@jaumo.com <benjamin.r...@jaumo.com>>* wrote ---- > > I use the self-compiled master (3.10, ticktock). I had to fix a severe bug > on my own and decided to go with the latest code. > Would you consider 3.0.x to be more stable than 3.x? > > 2016-10-04 18:14 GMT+02:00 Vladimir Yudovin <vla...@winguzone.com>: > > Hi Benjamin! > > >we now use CS 3.x and have been advised that 3.x is still not considered > really production ready. > > Did you consider using of 3.0.9? Actually it's 3.0 with almost an year > fixes. > > > Best regards, Vladimir Yudovin, > > > *Winguzone Inc <https://winguzone.com?from=list> - Hosted Cloud Cassandra > on Azure and SoftLayer.Launch your cluster in minutes.* > > > ---- On Tue, 04 Oct 2016 07:27:54 -0400 *Benjamin Roth > <benjamin.r...@jaumo.com <benjamin.r...@jaumo.com>>* wrote ---- > > Hi! > > I have a frequently used pattern which seems to be quite costly in CS. The > pattern is always the same: I have a unique key and a sorting by a > different field. > > To give an example, here a real life example from our model: > CREATE TABLE visits.visits_in ( > user_id int, > user_id_visitor int, > created timestamp, > PRIMARY KEY (user_id, user_id_visitor) > ) WITH CLUSTERING ORDER BY (user_id_visitor ASC) > > CREATE MATERIALIZED VIEW visits.visits_in_sorted_mv AS > SELECT user_id, created, user_id_visitor > FROM visits.visits_in > WHERE user_id IS NOT NULL AND created IS NOT NULL AND user_id_visitor > IS NOT NULL > PRIMARY KEY (user_id, created, user_id_visitor) > WITH CLUSTERING ORDER BY (created DESC, user_id_visitor DESC) > > This simply represents people, that visited my profile sorted by date desc > but only one entry per visitor. > Other examples with the same pattern could be a whats-app-like inbox where > the last message of each sender is shown by date desc. There are lots of > examples for that pattern. > > E.g. in redis I'd just use a sorted set, where the key could be like > "visits_${user_id}", set key would be user_id_visitor and score > the created timestamp. > In MySQL I'd create the table with PK on user_id + user_id_visitor and > create an index on user_id + created > In C* i use an MV. > > Is this the most efficient approach? > I also could have done this without an MV but then the situation in our > app would be far more complex. > I know that denormalization is a common pattern in C* and I don't hesitate > to use it but in this case, it is not as simple as it's not an append-only > case but updates have to be handled correctly. > If it is the first visit of a user, it's that simple, just 2 inserts in > base table + denormalized table. But on a 2nd or 3rd visit, the 1st or 2nd > visit has to be deleted from the denormalized table before. Otherwise the > visit would not be unique any more. > Handling this case without an MV requires a lot more effort, I guess even > more effort than just using an MV. > 1. You need kind of app-side locking to deal with race conditions > 2. Read before write is required to determine if an old record has to be > deleted > 3. At least CL_QUORUM is required to make sure that read before write is > always consistent > 4. Old record has to be deleted on update > > I guess, using an MV here is more efficient as there is less roundtrip > between C* and the app to do all that and the MV does not require strong > consistency as MV updates are always local and are eventual consistent when > the base table is. So there is also no need for distributed locks. > > I ask all this as we now use CS 3.x and have been advised that 3.x is > still not considered really production ready. > > I guess in a perfect world, this wouldn't even require an MV if SASI > indexes could be created over more than 1 column. E.g. in MySQL this case > is nothing else than a BTree. AFAIK SASI indices are also BTrees, filtering > by Partition Key (which should to be done anyway) and sorting by a field > would perfectly do the trick. But from the docs, this is not possible right > now. > > Does anyone see a better solution or are all my assumptions correct? > > -- > Benjamin Roth > Prokurist > > Jaumo GmbH · www.jaumo.com > Wehrstraße 46 · 73035 Göppingen · Germany > Phone +49 7161 304880-6 · Fax +49 7161 304880-1 > AG Ulm · HRB 731058 · Managing Director: Jens Kammerer > > > > > > > -- > Benjamin Roth > Prokurist > > Jaumo GmbH · www.jaumo.com > Wehrstraße 46 · 73035 Göppingen · Germany > Phone +49 7161 304880-6 · Fax +49 7161 304880-1 > AG Ulm · HRB 731058 · Managing Director: Jens Kammerer > > > > > > > -- > Benjamin Roth > Prokurist > > Jaumo GmbH · www.jaumo.com > Wehrstraße 46 · 73035 Göppingen · Germany > Phone +49 7161 304880-6 · Fax +49 7161 304880-1 > AG Ulm · HRB 731058 · Managing Director: Jens Kammerer >
