If I understand you've got a data model which looks like this:
CF Events:
"row1": { "event1": 1050, "event2": 1200, "event3": 830, ... }
You can't query on column values but you can build every day a ranking in
a dedicated CF by iterating over events:
create column family Ranking
with comparator = 'LongType(reversed=true)'
...
CF Ranking:
"rank": { 1200: "event2", 1050: "event1", 830: "event3", ... }
Then you can make a "top ten" or whatever you want because counter values
will be sorted.
Filippo Diotalevi <fili...@ntoklo.com> a écrit sur 21/05/2012 16:59:43 :
> Hi,
> I'm trying to understand what's the best design for a simple
> "ranking" use cases.
> I have, in a row, a good number (10k - a few 100K) of counters; each
> one is counting the occurrence of an event. At the end of day, I
> want to create a ranking of the most occurred event.
>
> What's the best approach to perform this task?
> The brute force approach of retrieving the row and ordering it
> doesn't work well (the call usually goes timeout, especially is
> Cassandra is also under load); I also don't know in advance the full
> set of event names (column names), so it's difficult to slice the get
call.
>
> Is there any trick to solve this problem? Maybe a way to retrieve
> the row ordering for counter values?
>
> Thanks,
> --
> Filippo Diotalevi
