What makes you think that RDBMS will give you acceptable performance?
I guess you will try to index it to death (because otherwise the "ad
hoc" queries won't work well if at all), and at this point you may be
hit with a performance penalty.
It may be a good idea to interview users and build denormalized views in
Cassandra, maybe on a separate "look-up" cluster. A few percent of users
will be unhappy, but you'll find it hard to do better. I'm talking from
my experience with an industrial strength RDBMS which doesn't scale very
well for what you call "ad-hoc" queries.
Regards,
Maxim
On 1/20/2012 9:28 AM, Brian O'Neill wrote:
I can't remember if I asked this question before, but....
We're using Cassandra as our transactional system, and building up
quite a library of map/reduce jobs that perform data quality analysis,
statistics, etc.
(> 100 jobs now)
But... we are still struggling to provide an "ad-hoc" query mechanism
for our users.
To fill that gap, I believe we still need to materialize our data in
an RDBMS.
Anyone have any ideas? Better ways to support ad-hoc queries?
Effectively, our users want to be able to select count(distinct Y)
from X group by Z.
Where Y and Z are arbitrary columns of rows in X.
We believe we can create column families with different key structures
(using Y an Z as row keys), but some column names we don't know /
can't predict ahead of time.
Are people doing bulk exports?
Anyone trying to keep an RDBMS in synch in real-time?
-brian
--
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/
