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 >>>> >>>
