I have now come to the task of estimating man-days to add "Blended Search Results" to Apache Solr. The argument has been made that this is not desirable (see Jonathan Rochkind's blog entries on Bento search with blacklight). But the estimate remains. No estimate is worth much without a design. So, I am come to the difficult of estimating this without having an in-depth knowledge of the Apache core. Here is my design, likely imperfect, as it stands.
- Configure a core specific to each search source (local or remote) - On cores that index remote content, implement a periodic delete query that deletes documents whose timestamp is too old - Implement a custom requestHandler for the "remote" cores that goes out and queries the remote source. For each result in the top N (configurable), it computes an id that is stable (e.g. it is based on the remote resource URL, doi, or hash of data returned). It uses that id to look-up the document in the lucene database. If the data is not there, it updates the lucene core and sets a flag that commit is required. Once it is done, it commits if needed. - Configure a core that uses a custom SearchComponent to call the requestHandler that goes and gets new documents and commits them. Since the cores for remote content are different cores, they can restart their searcher at this point if any commit is needed. The custom SearchComponent will wait for commit and reload to be completed. Then, search continues uses the other cores as "shards". - Auto-warming on this will assure that the most recently requested data is present. It will, of course, be very slow a good part of the time. Erik and others, I need to know whether this design has legs and what other alternatives I might consider. On Sun, Aug 18, 2013 at 3:14 PM, Erick Erickson <erickerick...@gmail.com>wrote: > The lack of global TF/IDF has been answered in the past, > in the sharded case, by "usually you have similar enough > stats that it doesn't matter". This pre-supposes a fairly > evenly distributed set of documents. > > But if you're talking about federated search across different > types of documents, then what would you "rescore" with? > How would you even consider scoring docs that are somewhat/ > totally different? Think magazine articles an meta-data associated > with pictures. > > What I've usually found is that one can use grouping to show > the top N of a variety of results. Or show tabs with different > types. Or have the app intelligently combine the different types > of documents in a way that "makes sense". But I don't know > how you'd just get "the right thing" to happen with some kind > of scoring magic. > > Best > Erick > > > On Fri, Aug 16, 2013 at 4:07 PM, Dan Davis <dansm...@gmail.com> wrote: > >> I've thought about it, and I have no time to really do a meta-search >> during >> evaluation. What I need to do is to create a single core that contains >> both of my data sets, and then describe the architecture that would be >> required to do blended results, with liberal estimates. >> >> From the perspective of evaluation, I need to understand whether any of >> the >> solutions to better ranking in the absence of global IDF have been >> explored? I suspect that one could retrieve a much larger than N set of >> results from a set of shards, re-score in some way that doesn't require >> IDF, e.g. storing both results in the same priority queue and *re-scoring* >> before *re-ranking*. >> >> The other way to do this would be to have a custom SearchHandler that >> works >> differently - it performs the query, retries all results deemed relevant >> by >> another engine, adds them to the Lucene index, and then performs the query >> again in the standard way. This would be quite slow, but perhaps useful >> as a way to evaluate my method. >> >> I still welcome any suggestions on how such a SearchHandler could be >> implemented. >> > >
