Questions about R and N (and W): 1. If I set R to Quorum and cassandra identifies a need for read repair before returning, would the read repair happen on R nodes (I mean subset of R that needs repair) or N nodes before the data is delivered to the client ? 2. Also does the repair happen at level of row (key) or at level of column ?
3. During write, if W is met but N-W is not met for some reason; would cassandra try to repair N-W nodes in the background as and when it can. Or the N-W are only repaired when a read is issued ? 4. What is the significance of the 'primary' replica for writes from usage point ? Writes to primary and non-primary replicas all happen simultaneously. Ensuring W is decided irrespective of it being primary or not. Ensuring R is decided by any of the R nodes out of N. I know the tokens are divided per the primary replica. But other than that, for read and write operations, do the primary replica play any special role ? Thanks.
