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From Brian O'Neill <b...@alumni.brown.edu>
Subject Re: Bitmap indexes - reviving CASSANDRA-1472
Date Thu, 11 Apr 2013 03:02:27 GMT

<changing to user@>
(at least until we can determine if this can/should be proposed under 1472)

For those interested in analytics and set-based queries, see below...

-brian

---
Brian O'Neill
Lead Architect, Software Development
Health Market Science
The Science of Better Results
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On 4/10/13 10:43 PM, "Matt Stump" <mrevilgnome@gmail.com> wrote:

>Druid was our inspiration to layer bitmap indexes on top of Cassandra.
>Druid doesn't work for us because or data set is too large. We would need
>many hundreds of nodes just for the pre-processed data. What I envisioned
>was the ability to perform druid style queries (no aggregation) without
>the
>limitations imposed by having the entire dataset in memory. I primarily
>need to query whether a user performed some event, but I also intend to
>add
>trigram indexes for LIKE, ILIKE or possibly regex style matching.
>
>I wasn't aware of CONCISE, thanks for the pointer. We are currently
>evaluating fastbit, which is a very similar project:
>https://sdm.lbl.gov/fastbit/
>
>
>On Wed, Apr 10, 2013 at 5:49 PM, Brian O'Neill
><bone@alumni.brown.edu>wrote:
>
>>
>> How does this compare with Druid?
>> https://github.com/metamx/druid
>>
>> We're currently evaluating Acunu, Vertica and Druid...
>>
>> 
>>http://brianoneill.blogspot.com/2013/04/bianalytics-on-big-datacassandra.
>>html
>>
>> With its bitmapped indexes, Druid appears to have the most potential.
>> They boast some pretty impressive stats, especially WRT handling
>> "real-time" updates and adding new dimensions.
>>
>> They also use a compression algorithm, CONCISE, to cut down on the space
>> requirements.
>> http://ricerca.mat.uniroma3.it/users/colanton/concise.html
>>
>> I haven't looked too deep into the Druid code, but I've been meaning to
>> see if it could be backed by C*.
>>
>> We'd be game to join the hunt if you pursue such a beast. (with your
>>code,
>> or with portions of Druid)
>>
>> -brian
>>
>>
>> On Apr 10, 2013, at 5:40 PM, mrevilgnome wrote:
>>
>> > What do you think about set manipulation via indexes in Cassandra? I'm
>> > interested in answering queries such as give me all users that
>>performed
>> > event 1, 2, and 3, but not 4. If the answer is yes than I can make a
>>case
>> > for spending my time on C*. The only downside for us would be our
>>current
>> > prototype is in C++ so we would loose some performance and the
>>ability to
>> > dedicate an entire machine to caching/performing queries.
>> >
>> >
>> > On Wed, Apr 10, 2013 at 11:57 AM, Jonathan Ellis <jbellis@gmail.com>
>> wrote:
>> >
>> >> If you mean, "Can someone help me figure out how to get started
>>updating
>> >> these old patches to trunk and cleaning out the Avro?" then yes, I've
>> been
>> >> knee-deep in indexing code recently.
>> >>
>> >>
>> >> On Wed, Apr 10, 2013 at 11:34 AM, mrevilgnome <mrevilgnome@gmail.com>
>> >> wrote:
>> >>
>> >>> I'm currently building a distributed cluster on top of cassandra to
>> >> perform
>> >>> fast set manipulation via bitmap indexes. This gives me the ability
>>to
>> >>> perform unions, intersections, and set subtraction across
>>sub-queries.
>> >>> Currently I'm storing index information for thousands of dimensions
>>as
>> >>> cassandra rows, and my cluster keeps this information cached,
>> distributed
>> >>> and replicated in order to answer queries.
>> >>>
>> >>> Every couple of days I think to myself this should really exist in
>>C*.
>> >>> Given all the benifits would there be any interest in
>> >>> reviving CASSANDRA-1472?
>> >>>
>> >>> Some downsides are that this is very memory intensive, even for
>>sparse
>> >>> bitmaps.
>> >>>
>> >>
>> >>
>> >>
>> >> --
>> >> Jonathan Ellis
>> >> Project Chair, Apache Cassandra
>> >> co-founder, http://www.datastax.com
>> >> @spyced
>> >>
>>
>> --
>> Brian ONeill
>> Lead Architect, Health Market Science (http://healthmarketscience.com)
>> mobile:215.588.6024
>> blog: http://weblogs.java.net/blog/boneill42/
>> blog: http://brianoneill.blogspot.com/
>>
>>



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