If you check the Jira issue I linked you'll see a recent comment describing a potential explanation for my mixed LWT/non-LWT problem. So, it looks like there can be some edge cases.
I'd say that if data was inserted a while ago (seconds) there should be no problems. -- Jacques-Henri Berthemet -----Original Message----- From: Hiroyuki Yamada [mailto:mogwa...@gmail.com] Sent: Sunday, March 25, 2018 1:10 AM To: user@cassandra.apache.org Subject: Re: LWT on data mutated by non-LWT operation is valid ? Thank you JH. But, it's still a little bit unclear to me Let me clarify the question. What I wanted to know is whether or not linearizability is sustained by doing LWT (Consistency: QUORUM, Serial Consistency: SERIAL) on data previously mutated by non-LWT (Consistency: QUORUM). I think It should be OK if non-LWT surely correctly happened before the LWT, but I'm wondering if there is a corner case where it's not OK. For example, to test LWT (Update) operations, initial data should be inserted by LWT operations ? or it can be non-LWT operations ? Thanks, Hiroyuki On Sat, Mar 24, 2018 at 8:27 PM, Jacques-Henri Berthemet <jacques-henri.berthe...@genesys.com> wrote: > Hi Hiroyuki, > > > For both operations you'll have to provide partition key so "conflict" > at DB level can always be resolved. > > But if two operations, LWT and non-LWT, are racing against each others > the result is unpredictable, if non-LWT is applied after LWT the > result will be overwritten. > > > It seems mixing LWT and non-LWT can result in strange results, we > recently opened a bug on non-working delete after LWT insert: > https://issues.apache.org/jira/browse/CASSANDRA-14304 > .apache.org > > > Regards, > > JH > > ________________________________ > From: Hiroyuki Yamada <mogwa...@gmail.com> > Sent: Saturday, March 24, 2018 4:38:15 AM > To: user@cassandra.apache.org > Subject: LWT on data mutated by non-LWT operation is valid ? > > Hi all, > > I have some question about LWT. > > I am wondering if LWT works only for data mutated by LWT or not. > In other words, doing LWT on some data mutated by non-LWT operations > is still valid ? > I don't fully understand how system.paxos table works in LWT, but > row_key should be empty for a data mutated by non-LWT operation, so > conflict resolution seems impossible. > It works only if a previous non-LWT operation is completely finished ? > > Thanks in advance. > > Best regards, > Hiroyuki > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org > For additional commands, e-mail: user-h...@cassandra.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org For additional commands, e-mail: user-h...@cassandra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org For additional commands, e-mail: user-h...@cassandra.apache.org
