From a disk format point of view the only thing I remember was the disk type bug with UDTs. Bringing that logic back was hard as the type system (in 5.0) tries to avoid allowing construction of invalid states, and we would need to weaken that in order to enable the migration. Assuming the user migrated from 3.x to 4.x then the sstable metadata should have been rewritten to fix this bug.
One thought (though know its a ton of effort).. we have talked about for a long time about moving the reading/writing logic into its jar (so tools don’t need cassandra-all and can limit the dependencies)… if we did that we could try to solve this as an out of process migration… have the 2.2 reader then write using 6.0 writer (ignoring compact storage… )… > On Dec 11, 2024, at 4:59 AM, Benedict <bened...@apache.org> wrote: > > I think 3.11 supported upgrade from 2.2, but I haven’t checked. I am fairly > sure 4.x supported upgrade from 3.0.x also. > > >> On 11 Dec 2024, at 12:53, Miklosovic, Stefan via dev >> <dev@cassandra.apache.org> wrote: >> >> I see. That makes sense. I think that by 3.x you meant basically the latest >> 3.11, right? I guess 2.2 -> 3.0 already works, we would just try to support >> 2.2 -> 3.11 straight away. I need to check where we are at in that area. >> >> ________________________________________ >> From: Benedict <bened...@apache.org> >> Sent: Wednesday, December 11, 2024 13:09 >> To: dev@cassandra.apache.org >> Cc: Miklosovic, Stefan; dev@cassandra.apache.org; Miklosovic, Stefan >> Subject: Re: Supporting 2.2 -> 5.0 upgrades >> >> EXTERNAL EMAIL - USE CAUTION when clicking links or attachments >> >> >> >> >> 2.2 is particularly hard because of the major storage format changes that >> took place. >> >> I think if we want to retain (restore) upgrade support from 3.x I would >> support that, but 2.x is probably too burdensome and likely to have too many >> hard edges. >> >> I think if users only had to upgrade 2.2->3.x then eg 3.x->6.0 that would be >> a pretty friendly upgrade path all things considered. >> >>> On 11 Dec 2024, at 12:03, Miklosovic, Stefan via dev >>> <dev@cassandra.apache.org> wrote: >>> >>> Hey, >>> >>> I want to fork the thread where we are mentioning that 2.2 -> 5.0 would be >>> cool to support. >>> >>> I was involved in checking that offline upgrades from 3.0 to 5.0 work and >>> fixed few issues along the way (1), hence I can imagine that supporting 2.2 >>> -> 5.0 would be basically the same thing just on steroids and more >>> involved? Anyway, having a stab into this is not useless at all, I will at >>> least go deep into the upgrade stuff I have never given a lot of thought to >>> which is good learning experience. >>> >>> Any tips where to start? Was any progress done by anybody already in this >>> matter to not start from zero? >>> >>> (1) >>> https://urldefense.com/v3/__https://issues.apache.org/jira/browse/CASSANDRA-19002__;!!Nhn8V6BzJA!RFZoz6sQSrP_qLd0K_eNWO3UAc1s8mTT5SkFalUMwM7_l9gWfb4cnfTFvdY68zsh5-REW7T8ALTPQwqMM_gWWSyp$ >>> >>> Regards >> >
