I am +1 on Benjamin’s proposal and less interruptions during upgrades. For more visibility maybe we can also write a short article about the options and the tradeoffs, further to NEWS.txt (that’s not something to decide now, of course :-) )
On Tue, 24 Nov 2020 at 9:13, Benjamin Lerer <benjamin.le...@datastax.com> wrote: > Paulo, what you propose with the yaml seems different from default to > *correctness*. It means to me that we are forcing the user to choose > between *correctness *and *performance*. Most of us have a good > understanding of the problem and it is a hard choice for us. I imagine that > most of the users do not fully understand LWTs and will not know what to > choose. Some might not even use LWTs and will suddenly be forced to make a > choice that they do not understand. It does not feel right to me to push > them to make that choice. > > I also agree with Benedict and Mick that it is a risky thing to do. > > something that can bring a cluster down upon an unprepared user. > > > I do not think that it will be the case (feel free to correct me Benedict). > The impact will probably be an increase in the number of write/read > timeouts for the LWTs read/writes. For a heavy load that would cause the > services depending on those queries to become unreliable. On the other hand > the impact of the current problem is that we can hit some correctness issue > without even knowing it. > > We need to choose between two imperfect solutions and we have some > difficulties to agree on which one to choose. > > Benedict suggested that Sylvain and I made the choice. Sylvain did not want > to make the final call. > I chose correctness. If it is a problem and people prefer to vote. It is > perfectly fine for me too :-) > > I just want us to move forward. > > > > On Tue, Nov 24, 2020 at 12:52 PM Mick Semb Wever <m...@apache.org> wrote: > > > > I think the keyword there is "normally" - if we can't say _certainly_, > > > then this is probably an unsafe change to make. > > > > > > I can imagine any number of hacky upgrade processes that would be > > > dangerous with this change. > > > > > > > > > I agree. We just don't know what users are doing, this is risky. > > > > IMO the same applies to a performance degradation, i.e. something that > can > > bring a cluster down upon an unprepared user. Despite our best efforts > with > > NEWS.txt we should still look after such users. IMHO the imperfection of > > LWTs on past branches we have to carry. I'm well aware this is easier > said > > than done, even for far simpler changes. Having the flag there to switch > to > > "correct LWT" is still a huge win for users. > > >
