> 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 >> >
