Hbase schema design -- to make sorting easy?

Question

I have 1M words in my dictionary. Whenever a user issue a query on my website, I will see if the query contains the words in my dictionary and increment the counter corresponding to them individually. Here is the example, say if a user type in "Obama is a president" and "Obama" and "president" are in my dictionary, then I should increment the counter by 1 for "Obama" and "president".

And from time to time, I want to see the top 100 words (most queried words). If I use Hbase to store the counter, what schema should I use? -- I have not come up an efficient one yet.

If I use word in my dictionary as row key, and "counter" as column key, then updating counter(increment) is very efficient. But it's very hard to sort and return the top 100.

Anyone can give a good advice? Thanks.

Answer 1

You can use the natural schema (row key as word and column as count) and use IHBase to get a secondary index on the count column. See https://issues.apache.org/jira/browse/HBASE-2037 for the initial implementation; the current code lives at http://github.com/ykulbak/ihbase.

Answer 2

Sorting 1M longs can be done in memory, so what?

Store words x,y,z issued at time t as key:t cols:word:x=1 word:y=1 word:z=1 in a table. Then use a MapRed job to sum up counts for words and get the top 100.

This also enables further analysis.