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 >>> >>
