I'd be happy to see this, but I agree with Scott and others that the implications around the auto_repair table-level property and the system_distributed tables that are added as part of CEP-37 should be thoroughly understood and vetted.
I also wanted to note a few things about a possible backport: * There is a branch that Jaydeep had been keeping in sync off of 4.1.6 ( https://github.com/apache/cassandra/pull/3367). I'm not sure how up to date it is but the last commit on the branch is Sep 21 2025. * As for "How far to backport", from previous discussions I know there has been an appetite to backport this to 4.1, but I'd be curious what the appetite would be for 4.0. I think if we backport it at all, we should be aiming at least for 4.1 as a minimum. * While the code in CEP-37 is rather isolated, maintaining it on 4.1+ should hopefully not add too much burden to maintain; however, we are benefitting from changes in 5.0 (CASSANDRA-20092) for simplifying getting amount of bytes a token range covers in an SSTable, where the 4.1 implementation makes some changes to BigTableScanner to get what we need ( https://github.com/apache/cassandra/pull/3367/files#diff-e8c75699e007d2ac1f3563865ee5b3769bae24eee75936e27c1d5c603aabd4cc), which are less optimal than the impl used on trunk (but maybe not enough to matter?). * Some API changes around TCM meant how we look up replicas in AutoRepair are different in 4.1/5.0 vs trunk. Andy On Tue, Dec 2, 2025 at 2:35 PM Brandon Williams <[email protected]> wrote: > It still changes the schema hash in 4.0, yeah. > > Kind Regards, > Brandon > > On Tue, Dec 2, 2025 at 2:34 PM Jeff Jirsa <[email protected]> wrote: > > > > Is it still the case (4.0, 4.1) where adding the table param changes the > schema hash (including in the mixed mode during the first deploy), or is > that a solved problem in 4.0+? > > > > > > > > > > > On Dec 2, 2025, at 2:54 PM, Brandon Williams <[email protected]> wrote: > > > > > > Maybe I was too hasty with my vote, then. I know from experience that > > > once table params or new system table properties are added, rolling > > > back is generally not possible. That can perhaps be fixed in some way > > > but nothing currently exists. > > > > > > Kind Regards, > > > Brandon > > > > > > On Tue, Dec 2, 2025 at 1:49 PM C. Scott Andreas <[email protected]> > wrote: > > >> > > >> The patch will need vetting for compatibility implications of > upgrades from (e.g.,) 4.0 + CEP-37 to newer-versioned releases like Apache > Cassandra 5.0.6 that don't have this change. > > >> > > >> Some sources of potential incompatibility (briefly scanned, not > vetted) look like: > > >> > > >> – Table params: > https://github.com/apache/cassandra/commit/6753fb49dcba6af6cccc02e62a5d425704d45b20#diff-44546e8ca2f2a8a986ec2b16f837b7526f2444e5fb2c6367abf35d8756fd0e51R578-R631 > > >> – system_distributed generation bump: > https://github.com/apache/cassandra/commit/6753fb49dcba6af6cccc02e62a5d425704d45b20#diff-68edc51628c3cf6a0e9dbcff0dd697e130b952e0f328699db5541a21300aa0b2R89-R104 > > >> – System table: > https://github.com/apache/cassandra/commit/6753fb49dcba6af6cccc02e62a5d425704d45b20#diff-68edc51628c3cf6a0e9dbcff0dd697e130b952e0f328699db5541a21300aa0b2R166 > > >> > > >> > > >> On Dec 2, 2025, at 11:36 AM, Josh McKenzie <[email protected]> > wrote: > > >> > > >> > > >> In a couple prior discuss threads, the topic of backporting > in-project repair scheduling (CEP-37) came up a few times and the consensus > seemed to be that everyone was receptive to us backporting this feature to > all GA branches. The goal of this thread is to focus on that and formalize > discussion and consensus before a potential vote. > > >> > > >> Here's a link to the CEP-37: > https://cwiki.apache.org/confluence/display/CASSANDRA/CEP-37%3A+Apache+Cassandra+Unified+Repair+Solution > > >> > > >> And a link to the JIRA for the impl: > https://issues.apache.org/jira/browse/CASSANDRA-19918 > > >> > > >> And here's the PR: > https://github.com/apache/cassandra/commit/6753fb49dcba6af6cccc02e62a5d425704d45b20 > > >> > > >> So: what do we think? > > >> > > >> I'm personally +1 on allowing this to be backported to 4.0, 4.1, and > 5.0. > > >> > > >> ----- > > >> Prior reading: > > >> - Discussing potential of a backport branch: > https://lists.apache.org/thread/xbxt21rttsqvhmh8ds9vs2cr7fx27w3k > > >> - Discussing understanding fork motivations: > https://lists.apache.org/thread/5nv1f4bng4nw5ofgh135k5pf2f6l6lgl > > >> > > >> > > >
