Detecting Hinted Handoff

DeadZen deadzen at deadzen.com
Mon Jul 25 06:25:30 EDT 2016


Hinted handoff from adding a node, removing a node or failing a node? Could
probably get some idea from a ring handler, hinted handoff could likely
very well trigger its own event as well without a large modification to
riak_core


On Sunday, July 24, 2016, Sargun Dhillon <sargun at sargun.me> wrote:

> It might also make a lot of sense to roll your own secondary indices. That
> is, have a CRDT set represent the primary key of the rows which meet the 2i
> condition. In that, you can query the CRDT set, and ensure some level of
> consistency. There are further tricks to be played here if interested.
>
> I'm curious, what is your data model?
>
> On Fri, Jul 22, 2016 at 11:01 AM, Alexander Sicular <siculars at gmail.com
> <javascript:_e(%7B%7D,'cvml','siculars at gmail.com');>> wrote:
>
>> Take a look at the "pw" and "pr" tunable consistency options for gets and
>> puts. The base level of abstraction in Riak is the virtual node - not the
>> physical machine. When data is replicated it is replicated to a replica set
>> of virtual nodes. Those virtual nodes have primary and secondary (due to
>> failures) allocations to physical machines. When using "pr" and "pw"
>> options you instruct Riak to only service the request from virtual nodes
>> that are residing on their primarily allocated physical machines. In short,
>> by abusing pr/pw you can infer the state of your cluster from your
>> application.
>>
>> Obviously, this is not foolproof. There may also be additional 2i
>> specific issues to consider. Nevertheless, I always liked this trick.
>>
>> Also, review this four part series on tunable consistency :
>>
>>
>> http://basho.com/posts/technical/understanding-riaks-configurable-behaviors-part-1/
>> http://basho.com/posts/technical/riaks-config-behaviors-part-2/
>> http://basho.com/posts/technical/riaks-config-behaviors-part-3/
>> http://basho.com/posts/technical/riaks-config-behaviors-part-4/
>>
>> -Alexander
>>
>>
>> @siculars
>> http://siculars.posthaven.com
>>
>> Sent from my iRotaryPhone
>>
>> On Jul 22, 2016, at 12:28, Hawk Newton <hawk.newton at gmail.com
>> <javascript:_e(%7B%7D,'cvml','hawk.newton at gmail.com');>> wrote:
>>
>> I've got a use case in which I'd like to use a secondary index but can't
>> tolerate partial result sets caused by hinted handoffs.  I'm not currently
>> running riak search and, as this is a fringe case, would prefer not add
>> the
>> additional overhead and complexity if I can help it.
>>
>> I'd like to detect a hinted handoff operation and throw a 503, if
>> possible.
>>
>> Does anyone know of a way I can programatically detect if a hinted handoff
>> is underway without having to shell out to riak-admin (yuck!) and parse
>> the
>> results? I'm running riak 2.0.5 at the moment.
>>
>> Thank you in advance.
>>
>> -- Hawk
>>
>>
>>
>> --
>> View this message in context:
>> http://riak-users.197444.n3.nabble.com/Detecting-Hinted-Handoff-tp4034489.html
>> Sent from the Riak Users mailing list archive at Nabble.com
>> <http://nabble.com>.
>>
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>
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