Nobody debates that it's easier, the debate is over whether or not it's correct (and more importantly, whether or not people realize it's not strictly correct in all edge cases).
Users expect correct results. People are literally betting their jobs on it. When you have to manually manage sync between two tables, you at least become (painfully) aware that correctness is difficult and you can't count on it (maybe you need an app level re-sync or similar). When you use a feature that is built in, people will assume it's correct, and there's no way for the average user to know that's not the case right now. Put another way: If your bank decided to use MVs right now for your personal bank/investment accounts, would you be ok with that? If not, then we need a way to stop the banks (and all other cassandra users) from doing it without realizing that it's not OK. On Tue, Oct 3, 2017 at 12:02 PM, Jake Luciani <jak...@gmail.com> wrote: > > > > The remaining issues are: > > > > * There's no way to determine if a view is out of sync with the base > table. > > * If you do determine that a view is out of sync, the only way to fix it > > is to drop and rebuild the view. > > * There are liveness issues with updates being reflected in the view. > > > > I just want to mention that manual de-normalization has all the same issues > as the list of above. If you write to multiple tables with batch logs when > do you know the data is consistent? > In fact, manual de-normalization is worse because you can't manually handle > updates to existing data due to the lack of synchronization on read before > write. > > I think a lot of you have lost sight on what MV was intended for, as a way > to keep developers from manually maintaining a consistent view of data > across tables. > There is still the fundamental problem of managing multiple views of data > even if you remove the MV feature, you just make it someone else's problem. > > I'll re-post this blog from back when MVs first came out to hopefully clear > questions up on the goals of MV. > > https://www.datastax.com/dev/blog/understanding-materialized-views > > -Jake > > > On Tue, Oct 3, 2017 at 2:50 PM, Aleksey Yeshchenko <alek...@apple.com> > wrote: > > > Indeed. Paulo and Zhao did a lot of good work to make the situation less > > bad. You did some as well. Even I retouched small parts of it - metadata > > related. I’m sorry if I came off as disrespectful - I didn’t mean to. > I’ve > > seen and I appreciate every commit that went into it. > > > > It is however my opinion that we started at a very low point, for a > > variety of reasons, and climbing out of that initial poor state, to the > > level that power users start having trust in MVs and overcome the initial > > deservedly poor impression, will probably take even more work. And > when/if > > we get there, maybe we won’t need the switch anymore. > > > > — > > AY > > > > On 3 October 2017 at 17:00:31, Sylvain Lebresne (sylv...@datastax.com) > > wrote: > > > > You're giving little credit to the hard work that people have put into > > getting MV in a usable state. > > > > > > -- > http://twitter.com/tjake >
