Using SERIAL is of course much more expensive, but then the trade-off is that you are guaranteed to have linearizability cross data-centers.
Please note that when using Lightweight Transactions, there 2 two distinct consistency levels to be set: 1) The Paxos phase consistency level: SERIAL or LOCAL_SERIAL (equivalent to QUORUM/LOCAL_QUORUM) 2) The commit/Cassandra write consistency level: any normal consistency level Please see this diagram: https://www.slideshare.net/doanduyhai/cassandra-introduction-parisjug/90 The Paxos consistency level applies to phases 1 to 3. The commit consistency level only applies to the last phase. On Sat, Sep 9, 2017 at 12:49 AM, Charulata Sharma (charshar) < chars...@cisco.com> wrote: > Thanks for your reply. I understand that LOCAL_SERIAL is for within a DC , > will setting up SERIAL not slow down the operation? > > And should I set SERIAL for both read and write phase or just Read phase? > This is becoming a big problem for us. It happens for a small percentage of > > data set but it happens daily because of the highly concurrent and random > DC routing of the received events. > > > > We had a counter implementation prior to CAS, which used to fail most of > the times. CAS provided a big relief but it is still not totally without > errors. > > Would really appreciate the community’s feedback. > > > > Thanks, > > Charu > > > > *From: *vasu gunja <vasu.no...@gmail.com> > *Reply-To: *"user@cassandra.apache.org" <user@cassandra.apache.org> > *Date: *Friday, September 8, 2017 at 1:56 PM > *To: *"user@cassandra.apache.org" <user@cassandra.apache.org> > *Subject: *Re: Lightweight transaction in Multi DC > > > > LOCAL_SERIAL is dc level, SERIAL checks for complete cluster level. > > > > On Fri, Sep 8, 2017 at 2:33 PM, Charulata Sharma (charshar) < > chars...@cisco.com> wrote: > > Yes …it is with LOCAL_SERIAL. Should I be using SERIAL ? > > > > Thanks, > > Charu > > > > *From: *DuyHai Doan <doanduy...@gmail.com> > *Reply-To: *"user@cassandra.apache.org" <user@cassandra.apache.org> > *Date: *Friday, September 8, 2017 at 12:30 PM > *To: *"user@cassandra.apache.org" <user@cassandra.apache.org> > *Subject: *Re: Lightweight transaction in Multi DC > > > > Are you using CAS with SERIAL consistency level for your multi-DC setup ? > > > > On Fri, Sep 8, 2017 at 9:27 PM, Charulata Sharma (charshar) < > chars...@cisco.com> wrote: > > Hi, > > We are facing a serious issue with CAS in a multi DC setup and I > wanted to get some input on it from the forum. > > > > We have a Column family which stores counts for the number of events our > application receives. When the counts reach a certain threshold, > > there is another process which kicks in. The issue that is happening is, > sometimes when concurrent events come in 2 Data Centers, both the events > read the same count > > and increment it to the same value which causes the next process to not > kick in. > > > > When concurrent events come in the same DC, this does not happen, because > in this case, the CAS explicitly fails for one of them. > > However, in case of Multiple DCs this is not happening. Has anyone faced a > similar issue and is there any resolution to this?? I was unable to find > any open Jira on this. > > > > Thanks, > > Charu > > > > > > > > >
