distribution of data among riak cluster physical nodes

kzhang kzhang at wayfair.com
Fri Oct 11 19:10:59 EDT 2013


I read the documentation again
(http://docs.basho.com/riak/latest/dev/references/http/fetch-object/).

r - (read quorum) how many replicas need to agree when retrieving the object
(default is defined by the bucket)
pr - how many primary replicas need to be online when doing the read
(default is defined by the bucket)
basic_quorum - whether to return early in some failure cases (eg. when r=1
and you get 2 errors and a success basic_quorum=true would return an error)
(default is defined by the bucket)
notfound_ok - whether to treat notfounds as successful reads for the
purposes of R (default is defined by the bucket)

If I have:

r = 1
notfound_ok=true
basic_quorum = true

does the client get notfound after 1 reply (since notfound_ok=true and r =
1) or after 2 replies (since basic_quorum = true)?

Or if I have:

r = 1
notfound_ok=false
basic_quorum = true

the client gets notfound if the first two replies are notfound? if the first
reply is found, the client gets found? if the first reply is notfound, the
second is found, does the client get found, or have to wait for the third
vnode (in my environment, N=3) to reply?

In the next setup:

r = 1
notfound_ok=false
basic_quorum = false

only when all three replies are notfound, then the client gets notfound?
otherwise, it is found.

The last one:

r = 1
notfound_ok=true
basic_quorum = false

which is the default. if the first reply is found, then client gets found.
if the first reply is notfound, clients gets notfound. 









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