Actually it is even easier than that. I am not trying to make a
histogram. I just need to find out what the various flavors are.
The flavors are not predefined - they are attributes of the data
records - so I can't ask for them specifically as in your second
suggestion. The SQL equivalent would be something like:
SELECT DISTINCT FLAVOR FROM BUCKET
I am just looking for a faster way to do it that does not slow down
if there a lot of *other* buckets in the whole db.
Since new records are added rarely, and in batches, it it not
outrageous to have to sweep through the flavor index at that time to
regenerate the summary information. By using a range query, the
impact on the database should be less than if I got all the keys
from the bucket, shouldn't it? Because indexes are specific to one
bucket as I understand it.
On 2/2/2012 9:40 AM, Ryan Zezeski wrote:
Carl,
There is currently no GROUP BY or aggregate function support
for Riak indexes. I think range query fed into map/reduce is a
good option. Another option is to run a 2i term query for each
flavor. Although, I would make sure to measure both. Also,
since you are storing the histogram in a meta-object that the
application will read you don't have to worry about the query
runtime affecting your application directly.
-Ryan
On Wed, Feb 1, 2012 at 5:23 PM, Carl <[email protected]>
wrote:
I have a bucket containing about 1,000 records. These
records are
indexed on a property let's call "flavor". There are only
about 10
different flavors.
Is there a way I could query the flavor_bin index to
discover what these
unique values are? The brute-force method would be a
map-reduce doing a
range query on 'flavor_bin' from 'AAAA' to 'zzzz' and then
boiling that
down to the unique values in the reduce phase. But that
would have to
retrieve every record in the bucket.
Is there some meta-data about the index I could query more
efficiently
to do this?
This is not something I would need to do very often, and I
would store
the resulting list in one record for actual use by the
application.
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