Keys not listed during vnode transfers

Mark Phillips mark at basho.com
Tue Apr 2 17:46:27 EDT 2013


Hi Daniel,

Sorry for the delay here.

It looks like it's going to take a more investigation to nail down the
cause. Engel just opened an issue you can keep an eye on:

https://github.com/basho/riak/issues/305

Thanks for reporting. Feel free to add any relevant information to the
issue.

Mark

On Thursday, March 14, 2013, Daniel Iwan wrote:

> Maybe someone from Basho could shed some light on that issue?
>
> Regards
> Daniel
>
>
> On 12 March 2013 11:55, Daniel Iwan <iwan.daniel at gmail.com<javascript:_e({}, 'cvml', 'iwan.daniel at gmail.com');>
> > wrote:
>
>> Just to add to that.
>> Further test shows that 2i searches aso suffer form the problem of not
>> showing all results durring active vnode transfer.
>> Is this a known issue with Riak 1.2.1? Has it been solved in 1.3?
>>
>> Anyone else experienced that? I guess attaching a node would trigger that
>> as well, maybe in less severe way.
>> Also I've read somewhere that you should attach one node at a time to
>> Riak cluster, and wait until vnode transfer completes.
>> I think it's no longer true in 1.2 since you have a plan that you commit,
>> but attaching a node and shuffling vnodes will cause problem described
>>
>> What is the solution here? Waiting until vnode transfer finishes is not
>> acceptable (availability) and recent findings show it may take a while on
>> big clusters.
>>
>> Regards
>> Daniel
>>
>>
>>
>> On 11 March 2013 23:06, Daniel Iwan <iwan.daniel at gmail.com<javascript:_e({}, 'cvml', 'iwan.daniel at gmail.com');>
>> > wrote:
>>
>>> I'm aware that listing keys is not for production.
>>> I'm using it mainly during testing, which started to be unreliable after
>>> changes described above.
>>>
>>> What I was not expecting at all was that some of the keys won't be
>>> listed.
>>> I'm not sure if that is stated in documentation to tell the truth.
>>> To me it looks like it should be called 'listSomeKeys'
>>>
>>> About alternatives.
>>> Some time ago I did comparison of listing and 2i and MapReduce and
>>> surprisingly listing was quickest.
>>> I'm not sure why it was happening. I did similar tests today and what I
>>> got is:
>>>
>>> 1000 keys, grouped with 2i into 10 equal groups, each value < 1kB
>>> Listing:
>>> - via listkeys  276ms
>>> - via keyindex $key: 255ms
>>> - via 2i (10 calls), total 2480ms
>>>
>>> So for that simple case 2i is 10 times slower.
>>> Further test shows that 100k keys (100 groups, 1000 each) gives query
>>> response between 250-5500ms.
>>> Not good. It's almost silly NOT to use listing keys.
>>>
>>> I may need to do that test on different hardware to compare. At the
>>> moment I'm using just one 7200rpm HDD for Riak db.
>>>
>>> Daniel
>>>
>>>
>>
>
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