gistfile1.txt

gotascii # i'm reading the forcing read repair section on the wiki, 
and some of it is a little unclear to me...how could you end up with a
failed read by increasing the r val on a bucket? one way i came up with
was if your r val is less than or equal to the change in r val you could 
get a whole set of node not found reads

seancribbs # gotascii: all you need is one fewer successful responses 
than R for the read to fail

gotascii # i.e. you go from 3 to 5 and then try to do a read with r = 2...you 
could get back the 2 nodes that don't have the data

seancribbs # but read repair happens regardless

gotascii: no, it'll wait until it at least 3 nodes say not found

gotascii # i thought in the instance where 1 of the R nodes doesnt 
have the obj but the other do, that it will auto red repair

seancribbs # or you get 2 successes whenever you read, yes, it repairs. 
regardless of the response to the client

gotascii # ah ok so it would send back a failure, and then repair

seancribbs # yes

gotascii # gotcha. and that is because doing it the other way would 
create a potentially high latency read while the client is waiting for the 
repair to take place...in the case of repairs that take a long time

gotascii # kinda obvious now that you've explained it heh, thanks sean!

gotascii # another reason read repair might happen is if two nodes respond 
and one node has a stale vector clock (not a divergent vector clock, but a 
definitively stale one)...in this case would the read be successful, 
return the latest obj, and then repair the stale node?

seancribbs # yes, if they can be resolved to a common lineage

justinsheehy # gotascii: yes, exactly. the "old" one will be read-repaired 
and replaced with the new one.

gotascii # which is different than if one node replies "not found" and 
the other replies "found"

seancribbs # right

gotascii # in that case the read would fail, and then behind the scenes 
it would repair

seancribbs # yes

gotascii # awesome, last repair ?..in the wiki it says to force read 
repair set R to the previous n and read all the objs...couldnt that 
result in a case where the original set of n replies for R

gotascii # and a repair doesn't happen

seancribbs # gotascii: that's the thing, even if you don't get all
 N replies, it will repair

gotascii # so even if i get a full read quorum of found objects, it will 
repair the other replicas that dont have it

seancribbs # yes

gotascii # wow, riak is pretty awesome

seancribbs # gotascii: it actually waits for all participating 
partitions to reply or timeout before repairing

gotascii # that is way cool