You're ignoring the other side here. For the folks who *can't* use LCS, defaulting to it is a nightmare.
Sorry, but you can't screw over 20% of the community to make life a little better for the 80%. This is a terrible tradeoff. Jon On Fri, Dec 6, 2024 at 8:36 PM Dinesh Joshi <djo...@apache.org> wrote: > I would argue that vast majority of real world workloads are read heavy. > LCS would therefore be a net benefit for the average user. > > To mitigate the write amplification concern I would make this change and > make sure it is well documented for operators so they’re not caught off > guard. > > On Fri, Dec 6, 2024 at 8:06 PM Jeff Jirsa <jji...@gmail.com> wrote: > >> And it works for that most of the time, so what’s the concern? “You lose >> throughput because iops / write amplification go up, so the perf of the >> default install goes down” ? (But the cost per byte goes way down, too)? >> >> >> >> On Dec 6, 2024, at 8:01 PM, Brad <bscho...@gmail.com> wrote: >> >> > Could you elaborate what you mean by 'disk storage management'? >> >> I often see clusters use LCS as an easy fix to avoid the 50% disk free >> recommendation of STCS without considering the write >> magnification implications. >> >> On Fri, Dec 6, 2024 at 10:46 PM Dinesh Joshi <djo...@apache.org> wrote: >> >>> Could you elaborate what you mean by 'disk storage management'? >>> >>> On Fri, Dec 6, 2024 at 7:30 PM Brad <bscho...@gmail.com> wrote: >>> >>>> I'm -1 on LCS being the default, seen far too many people use it for >>>> disk storage management >>>> >>>> On Fri, Dec 6, 2024 at 10:08 PM Jon Haddad <j...@rustyrazorblade.com> >>>> wrote: >>>> >>>>> I'm -1 on LCS being the default, since using it in the wrong >>>>> situations renders clusters inoperable. >>>>> >>>>> >>>>> On Fri, Dec 6, 2024 at 7:03 PM Paulo Motta <pa...@apache.org> wrote: >>>>> >>>>>> > I'd prefer to see the default go from STCS to UCS >>>>>> >>>>>> I’m proposing this for latest unstable (cassandra_latest.yaml) since >>>>>> it’s a more recent strategy still being adopted. For latest stable >>>>>> (cassandra.yaml) I’d prefer LCS since it does not need tuning to support >>>>>> mutable workloads (UPDATE/DELETE) and is battle-tested. >>>>>> >>>>>> On Fri, 6 Dec 2024 at 21:37 Jon Haddad <j...@rustyrazorblade.com> >>>>>> wrote: >>>>>> >>>>>>> I'd prefer to see the default go from STCS to UCS, probably with >>>>>>> scaling_parameters T4. That's essentially the same as STCS but without >>>>>>> the >>>>>>> ridiculous SSTable growth, allowing us to leverage the fast streaming >>>>>>> path >>>>>>> more often. I don't think there's any valid use cases for STCS anymore >>>>>>> now >>>>>>> that we have UCS. >>>>>>> >>>>>>> That said, many have taken issue with the state of UCS docs, myself >>>>>>> included, so that would need to be addressed with any default change. >>>>>>> >>>>>>> I don't think we should mark TWCS as experimental. Maybe we prevent >>>>>>> repairs to tables using TWCS, or do a better job of encouraging folks to >>>>>>> use incremental repair at higher frequencies. It's definitely not >>>>>>> experimental though. >>>>>>> >>>>>>> Side note: I think experimental has been over-used and has lost all >>>>>>> meaning. How is Java 17 experimental? Very confusing for the >>>>>>> community. >>>>>>> >>>>>>> I think TWCS should use UCS under the hood which would address >>>>>>> streaming performance (and thus node density) or UCS could be updated to >>>>>>> allow for time window's options. Either would solve issue #3 in your >>>>>>> list. >>>>>>> >>>>>>> Jon >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Fri, Dec 6, 2024 at 5:36 PM Paulo Motta <pa...@apache.org> wrote: >>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> It’s 2024 and users are still facing issues due to misconfigured >>>>>>>> compaction when using default configuration. >>>>>>>> >>>>>>>> I would like to start a conversation around improving compaction >>>>>>>> defaults in 5.1/trunk, so users trying out CQL transactions don’t need >>>>>>>> to >>>>>>>> worry about tuning compaction. >>>>>>>> >>>>>>>> A few suggestions: >>>>>>>> >>>>>>>> 1) Make LeveledCompactionStrategy default on cassandra.yaml, UCS >>>>>>>> default on cassandra_latest.yaml ? >>>>>>>> >>>>>>>> 2) Does TWCS work out of the box with repairs and hints? My >>>>>>>> understanding is that due to CASSANDRA-10496 this causes droppable >>>>>>>> tombstone issues when in combination with repair and hints (see more on >>>>>>>> this thread [1]). We should either fix this or mark TWCS experimental. >>>>>>>> >>>>>>>> 3) When STCS is used with deletions/TTL, tombstones accumulate in >>>>>>>> higher level stables when unchecked_tombstone_compaction is disabled >>>>>>>> (see >>>>>>>> CASSANDRA-6563). I propose having adding a new setting “auto” enabled >>>>>>>> by >>>>>>>> default that will have this set to true when STCS/TWCS is used. >>>>>>>> >>>>>>>> I believe addressing these points will improve user experience with >>>>>>>> Cassandra. >>>>>>>> >>>>>>>> I apologize in advance if these topics were discussed in recent >>>>>>>> threads. I would be happy to get pointers of related discussions on >>>>>>>> this >>>>>>>> topic. >>>>>>>> >>>>>>>> I will be happy to create JIRA if there’s agreement on addressing >>>>>>>> these items. >>>>>>>> >>>>>>>> Thanks, >>>>>>>> >>>>>>>> Paulo >>>>>>>> >>>>>>>> [1] - >>>>>>>> >>>>>>>> https://user.cassandra.apache.narkive.com/VQOacfnT/twcs-repair-create-new-buckets-with-old-data >>>>>>>> >>>>>>> >>
