MR tools, especially high level wrappers like cascading (which gives you capability to do easy joins on Hadoop) are very good for building indices for query. Yo

MR tools, especially high level wrappers like cascading (which gives you capability to do easy joins on Hadoop) are very good for building indices for query. You can use these tools to process the (log) data once and load the results into a scalable db like Hypertable (or even MySQL if the results set is small) and query them.