should't there be a way to do it efficiently for any indexed field (even max in byte order)? Term dict is sorted
On May 17, 2013, at 12:08 PM, "Uwe Schindler" <u...@thetaphi.de> wrote: > Hi, > > Depending on the distinct number of actual values, it might be better to > iterate over the term dictionary and not index as doc-values. The lowest > value is easy to get, just seek to the first term in the dictionary. The last > term is unfortunately not so easy to get, you have to iterate the term > dictionary until you reach the last term. > > Uwe > > ----- > Uwe Schindler > H.-H.-Meier-Allee 63, D-28213 Bremen > http://www.thetaphi.de > eMail: u...@thetaphi.de > > >> -----Original Message----- >> From: Adrien Grand [mailto:jpou...@gmail.com] >> Sent: Friday, May 17, 2013 11:36 AM >> To: java-user@lucene.apache.org >> Subject: Re: how to get max value of a long field? >> >> Hi, >> >> On Fri, May 17, 2013 at 11:10 AM, Hu Jing <huj....@gmail.com> wrote: >>> I want to know the max value of a long field. >>> I read lucene api , but don't find any api about this? >>> does someone can supply any hits about how to implement this. >> >> To do this efficiently, your field needs to have doc values[1]. >> >> First, iterate over your DirectoryReader leaves[2]. Then for every >> AtomicReaderContext.reader(), get a NumericDocValues instance for your >> field[3]. Then iterate over the values to compute the maximum value: >> >> IndexReader rd; >> long max = Long.MIN_VALUE; >> for (AtomicReaderContext ctx : rd.leaves()) { >> final NumericDocValues longs = >> ctx.reader().getNumericDocValues("my_long_field"); >> final Bits liveDocs = ctx.reader().getLiveDocs(); >> for (int i = 0; i < ctx.reader().maxDoc(); ++i) { >> if (liveDocs != null || liveDocs.get(i)) { >> max = Math.max(max, longs.get(i)); >> } >> } >> } >> >> [1] >> http://lucene.apache.org/core/4_3_0/core/org/apache/lucene/document/ >> NumericDocValuesField.html >> [2] >> http://lucene.apache.org/core/4_3_0/core/org/apache/lucene/index/Index >> Reader.html#leaves() >> [3] >> http://lucene.apache.org/core/4_3_0/core/org/apache/lucene/index/Atomi >> cReader.html#getNumericDocValues(java.lang.String) >> >> -- >> Adrien >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org >> For additional commands, e-mail: java-user-h...@lucene.apache.org > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
