If you’re at RF= 3 and read/write at quorum, you’ll have full visibility of all data if you switch to RF=4 and continue reading at quorum because quorum if 4 is 3, so you’re guaranteed to overlap with at least one of the two nodes that got all earlier writes
Going from 3 to 4 to 5 requires a repair after 4. > On Jun 28, 2019, at 8:32 PM, Oleksandr Shulgin <oleksandr.shul...@zalando.de> > wrote: > >> On Fri, Jun 28, 2019 at 11:29 PM Jeff Jirsa <jji...@gmail.com> wrote: > >> you often have to run repair after each increment - going from 3 -> 5 means >> 3 -> 4, repair, 4 -> 5 - just going 3 -> 5 will violate consistency >> guarantees, and is technically unsafe. > > Jeff, > > How going from 3 -> 4 is *not violating* consistency guarantees already? Are > you assuming quorum writes and reads and a perfectly repaired keyspace? > > Regards, > -- > Alex >
