Re: What does ReadRepair exactly do?

2012-10-25 Thread shankarpnsn
manuzhang wrote > read quorum doesn't mean we read newest values from a quorum number of > replicas but to ensure we read at least one newest value as long as write > quorum succeeded beforehand and W+R > N. I beg to differ here. Any read/write, by definition of quorum, should have at least n/2 +

Re: What does ReadRepair exactly do?

2012-10-24 Thread shankarpnsn
Hiller, Dean wrote > I guess one more thing is I completely ignore your second write mainly > because I assume it comes after we already read so your let's say you > current state is > > node1 = val1 node2 = val1 node3 = val1 > > You do a write quorom of val=2 which is IN the middle!!! > > node1

Re: What does ReadRepair exactly do?

2012-10-24 Thread shankarpnsn
Hiller, Dean wrote > in general it is okay to get the older or newer value. If you are reading > 2 rows however instead of one, that may change. This is certainly interesting, as it could mean that the user could see a value that never met the required consistency. For instance with 3 replicas a

Re: What does ReadRepair exactly do?

2012-10-23 Thread shankarpnsn
manuzhang wrote > why repair again? We block until the consistency constraint is met. Then > the latest version is returned and repair is done asynchronously if any > mismatch. We may retry read if fewer columns than required are returned. Just to make sure I understand you correct, considering th

Re: What does ReadRepair exactly do?

2012-10-23 Thread shankarpnsn
Hello, This conversation precisely targets a question that I had been having for a while - would be grateful if you someone cloud clarify it a little further: Considering the case of a "repair" created due to a consistency constraint (first case in the discussion above), would the following int