Does Riak support Range Queries over binary safe strings?

gbrits gbrits at gmail.com
Wed Jul 17 06:31:19 EDT 2013


Sounds good to me. Just to confirm: the value which I want to get a slice
from can be a bytearray encoded as a string? (base 255)?

Oh and almost forgot, I DO need to be able to parameterize the m/r (with
param startSliceAt, endSliceAt + some other parameters that manage how
aggregation of values is performed) .
Being an absolute noob to m/r is this possible?




2013/7/17 Alexander Sicular [via Riak Users] <
ml-node+s197444n4028365h18 at n3.nabble.com>

> To the extent you limit your sliced data via an m/r you will reap those
> savings on the wire when transferring back to the client
>
> You can feed an m/r from riak search, 2i or enumerated keys thereby
> skipping a costly bucket scan.
>
>
> @siculars
> http://siculars.posthaven.com
>
> Sent from my iRotaryPhone
>
> On Jul 16, 2013, at 19:46, Jeremiah Peschka <[hidden email]<http://user/SendEmail.jtp?type=node&node=4028365&i=0>>
> wrote:
>
> Not a problem.
>
> MapReduce across an entire keyspace is slow.
>
> MapReduce when provided with a few bucket/key pairs is the same as a
> multi-get + processing.
>
> You can combine 2i + MR to get quick processing of data. Although, at that
> point, you might as well just process your data on the client side.
> Especially if you're just pulling out a slice of bytes.
>
> ---
> Jeremiah Peschka - Founder, Brent Ozar Unlimited
>  MCITP: SQL Server 2008, MVP
> Cloudera Certified Developer for Apache Hadoop
>
>
> On Tue, Jul 16, 2013 at 4:13 PM, gbrits <[hidden email]<http://user/SendEmail.jtp?type=node&node=4028365&i=1>
> > wrote:
>
>> Wow, high speed on this list!
>>
>> I wanted it for near realtime anyway so Map/reduce is out of the
>> question. Thought somehow it could be done through Riak Search or directly
>> on secondary indices instead of map/reduce.
>> Guess not. Oh well, can't have it all.
>>
>> Thanks
>>
>>
>> 2013/7/17 Jeremiah Peschka [via Riak Users] <[hidden email]<http://user/SendEmail.jtp?type=node&node=4028360&i=0>
>> >
>>
>>> Following up on Alex's comments -
>>>
>>> If you know which bytes you need to slice, you can store this in a
>>> secondary index. You can perform range queries across secondary indices (as
>>> well as keys).
>>>
>>> As long as you're storing your data in a way that allows it to be read
>>> by either Erlang or JavaScript, you should be able to query over it in
>>> MapReduce. This is typically regarded as a Bad Idea™ since an MR query will
>>> need to scan all keys in a bucket (which effectively means scanning the
>>> entire cluster) and is best done as an infrequent activity to transform
>>> data.
>>>
>>> ---
>>> Jeremiah Peschka - Founder, Brent Ozar Unlimited
>>>  MCITP: SQL Server 2008, MVP
>>> Cloudera Certified Developer for Apache Hadoop
>>>
>>>
>>> On Tue, Jul 16, 2013 at 3:45 PM, Alexander Sicular <[hidden email]<http://user/SendEmail.jtp?type=node&node=4028359&i=0>
>>> > wrote:
>>>
>>>> I would say no. Riak is generally oblivious as to the content of your
>>>> data. Any ranges or other method you would use to query needs to be
>>>> explicitly indexed via riak search or secondary indexes. Once you have
>>>> found your data you could operate over that data in a map reduce, but I
>>>> can't speak to "binary safe" blob operations in either erlang or JavaScript
>>>> although I'm inclined to say yes, you would be able to operate over it in
>>>> m/r.
>>>>
>>>> So searching for keys with certain data in the binblob is probably not
>>>> gonna happen but once you have a key to feed an m/r you could get a slice
>>>> of that value.
>>>>
>>>> Make sense?
>>>> -Alexander
>>>>
>>>> @siculars
>>>> http://siculars.posthaven.com
>>>>
>>>> Sent from my iRotaryPhone
>>>>
>>>> On Jul 16, 2013, at 18:17, gbrits <[hidden email]<http://user/SendEmail.jtp?type=node&node=4028359&i=1>>
>>>> wrote:
>>>>
>>>> > First, hello all!
>>>> >
>>>> > Coming from Redis, I love that you can just put any binary blob in
>>>> Redis
>>>> > which is just treated as a string. This is possible because Redis
>>>> strings
>>>> > are what they call 'binary safe'. This makes it possible to return
>>>> slices of
>>>> > string-encoded binary data, which is super useful for
>>>> bitset-operations,
>>>> > etc.
>>>> >
>>>> > I'm investigating Riak and I like it a lot so far. Riak seems to have
>>>> range
>>>> > queries (on values, as it seems I must make that distinction with
>>>> > column-stores), but I'm not sure if strings in Riak are "Binary safe"
>>>> in the
>>>> > above sense. If not, is there another way to store binary data in
>>>> Riak and
>>>> > still do range queries over them quickly?
>>>> >
>>>> > To be exact: I want to do multi-key lookups in Riak, where each
>>>> returned
>>>> > result should be of format: <key,slice(featureX,start,end)>
>>>> >
>>>> > Thanks,
>>>> > Geert-Jan
>>>> >
>>>> >
>>>> >
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