Thank you Dipan, it makes sense now. Cheers, Anurag
On Sun, Jul 16, 2023 at 12:43 AM Dipan Shah <dipan.s...@anant.us> wrote: > Hello Anurag, > > In Cassandra, Strong consistency is guaranteed when "R + W > N" where R is > Read consistency, W is Write consistency and N is the Replication Factor. > > So in your case, R(2) + W(1) = 3 which is NOT greater than your > replication factor(3) so you will not be able to guarantee strong > consistency. This is because you will write to 1 replica but your immediate > read can go to the other 2(quorum) replicas and they might not be updated > yet. > > On Sun, Jul 16, 2023 at 8:06 AM Anurag Bisht <bisht.anurag...@gmail.com> > wrote: > >> thank you Jeff, >> it makes more sense now. How about I write with ONE consistency, >> replication factor = 3 and read consistency is QUORUM. I am guessing in >> that case, I will not have the empty read even if it is happened >> immediately after the write request, let me know your thoughts ? >> >> Cheers, >> Anurag >> >> On Sat, Jul 15, 2023 at 7:28 PM Jeff Jirsa <jji...@gmail.com> wrote: >> >>> Consistency level controls when queries acknowledge/succeed >>> >>> Replication factor is where data lives / how many copies >>> >>> If you write at consistency ONE and replication factor 3, the query >>> finishes successfully when the write is durable on one of the 3 copies. >>> >>> It will get sent to all 3, but it’ll return when it’s durable on one. >>> >>> If you write at ONE and it goes to the first replica, and you read at >>> ONE and it reads from the last replica, it may return without the data: >>> you may not see a given write right away. >>> >>> > On Jul 15, 2023, at 7:05 PM, Anurag Bisht <bisht.anurag...@gmail.com> >>> wrote: >>> > >>> > >>> > Hello Users, >>> > >>> > I am new to Cassandra and trying to understand the architecture of it. >>> If I write to ONE node for a particular key and have a replication factor >>> of 3, would the written key will get replicated to the other two nodes ? >>> Let me know if I am thinking incorrectly. >>> > >>> > Thanks, >>> > Anurag >>> >> > > -- > > Thanks, > > *Dipan Shah* > > *Data Engineer* > > [image: https://www.anant.us/Home.aspx] > > > 3 Washington Circle NW, Suite 301 > > Washington, D.C. 20037 > > > *Check out our **blog* <https://blog.anant.us/>*!* > > > This email and any attachments to it may be confidential and are intended > solely for the use of the individual to whom it is addressed. Any views or > opinions expressed are solely those of the author and do not necessarily > represent those of Anant Corporation. If you are not the intended recipient > of this email, you must neither take any action based upon its contents, > nor copy or show it to anyone. Please contact the sender if you believe you > have received this email in error. >
