Hi, Nan, The class ibis::query does support a function called estimate. You will need to update your copy of FastBit source code from the SVN repository (give it some time, the web site hosting the repository is currently down).
The sequence of function call should be something like 1. bis::query aquery(ibis::util::userName(), &table); 2. aquery.setWhereClause (wc.str().c_str()); 3. aquery.estimate(); 4. vector <uint32_t> RIDs; 5. aquery.getCandidateRows(RIDs); Let us know if you have any questions. John On 5/8/13 9:45 AM, nan zhou wrote: > Dear author, > > Is that possible we can enable fastbit to answer the query ( says, > 1 < a < 10 AND 2< b < 5 ) only by looking up index? I don't need the > exact answer now, only approximate answer will be fine. Currently, I > have codes like following: > > 1. bis::query aquery(ibis::util::userName(), &table); > 2. aquery.setWhereClause (wc.str().c_str()); > 3. aquery.evaluate (); > 4. vector <uint32_t> RIDs; > 5. aquery.getHitRows (RIDs); > > But I found out for some queries, fastbit need to retrieve data from > raw data. I verified this by following : > 1. remove the raw data under fastbit folder > 2. do the query > 3. if there is no error, it means fastbit does not touch the data > 4. otherwise (fastbit complains missing raw data), it means fastbit > touches the raw data > > is there some APIs which allow me to do that ? > > thanks > > nan > > > _______________________________________________ > FastBit-users mailing list > [email protected] > https://hpcrdm.lbl.gov/cgi-bin/mailman/listinfo/fastbit-users > _______________________________________________ FastBit-users mailing list [email protected] https://hpcrdm.lbl.gov/cgi-bin/mailman/listinfo/fastbit-users
