Well, under the covers, the old Hits object *was* reloading the first N pages to get page N + 1, you just didn't see it. Hits also had other, undesirable behaviors.
But "loading docs N-1 times" it's not as expensive as you perhaps fear. To get a sorted list, you must sort the entire set of documents. Which means to get, say, page 3 in some sort order, somewhere, sometime you must keep track of the scores for documents 1-200 in order to insure that docs 201-300 are really in the proper place. Since a TopDocs is just an int/float pair we're not talking about much memory. So I'd advise just going about it as you outlined. The *real* savings would be in not re-executing the search every page, but I wouldn't think about a caching scheme unless you demonstrate a problem. And if you were making due with Hits before, I suspect this isn't really a problem.... Best Erick On Thu, Apr 16, 2009 at 10:58 AM, Ivan Vasilev <ivasi...@sirma.bg> wrote: > Hi All, > > As Hits class was deprecated in current Lucene and is expected to be > excluded from Lucene 3.0 we decided to change our code so that to use > TopDocs class. > Our app provides paging and now we are uondering what is the bset way to do > it with th TopDocs. I can see only this possibility: > 1. User opens page 1 - we load by searcher.search(..., docNum, ... ) method > as many docs as for page 1; > 2. User opens page 2 - we load as many results as the amount for page 1 and > page 2 (note that docs for page 1 are loaded again); > ... > N. User opens page n - we load as many docs as the amount of all pages from > #1 to #N (note that page 1 docs were loaded N-1 times, page 2 docs N-2 times > etc). > > With Hits class this loading of documents of previous pages was avoided - > they were loaded once and when needed docs for the next page Hits just > loaded the next portion of docs without reloading the previous pages. > > So my question is: > Is there better way for paging with the class TopDocs than the one that I > describe here? > > Thanks in Advance, > Ivan > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > >
