The AND default has one big problem. If the user misspells a single word, they get no results. About 10% of queries are misspelled, so that means a lot more failures.
wunder Walter Underwood wun...@wunderwood.org http://observer.wunderwood.org/ (my blog) On Jul 15, 2015, at 7:21 AM, Jack Krupansky <jack.krupan...@gmail.com> wrote: > It is simply precision (AND) vs. recall (OR) - the former tries to limit > the total result count, while the latter tries to focus on relevancy of the > top results even if the total result count is higher. > > Recall is good for discovery and browsing, where you sort of know what you > generally want, but not exactly with any great precision. > > Recall will include results that almost meet the query terms, but maybe > some are missing. > > Precision will guarantee and insist that all query terms are present. > > One great example for recall is a plagiarism query - enter all the terms > for a passage and then find documents that most closely approximate the > passage without being necessarily exact matches. IOW, the plagiarizer > changes a word here and there. > > -- Jack Krupansky > > On Wed, Jul 15, 2015 at 8:16 AM, Steven White <swhite4...@gmail.com> wrote: > >> Hi Everyone, >> >> Out-of-the box, Solr (Lucene?) is set to use OR as the default Boolean >> operator. Can someone tell me the advantages / disadvantages of using OR >> or AND as the default? >> >> I'm leaning toward AND as the default because the more words a user types, >> the narrower the result set should be. >> >> Thanks >> >> Steve >>
