Performance may be worse with stored fields indeed. In general Lucene makes the assumption that millions of documents are queried but only ~100 documents are retrieved in the end, so the bottleneck should be query processing, not retrieving stored fieds.
Le ven. 13 avr. 2018 à 05:27, Yonghui Zhao <zhaoyong...@gmail.com> a écrit : > My case is when I get some docs from lucene, I need also get some field > value of the retrieved docs. > > For example in lucene 4, I use FieldCache like this. > > FieldCache.DEFAULT.getTerms(reader, name, > false).get(locDocId).utf8ToString(); > > FieldCache.DEFAULT.getInts(reader, name, false).get(locDocId); > > FieldCache.DEFAULT.getDoubles(reader, name, false).get(locDocId); > > > while docId may be not in ascending order. > > Of course I can use stored field like this > > Document doc = indexSearcher.doc(docId, storedFields.keySet()); > > > But the performance should be worse than FieldCache. > > > 2018-04-12 19:57 GMT+08:00 Adrien Grand <jpou...@gmail.com>: > > > Hello, > > > > Doc values should be used instead of the field cache indeed. Note that > this > > require to add them to your documents at index time, eg. with a > > NumericDocValuesField. > > > > Regarding random access, maybe you can use the advanceExact API, which > > exists on all doc-value iterators. Just make sure to never call it on > > decreasing doc IDs. If that doesn't work for you, can you describe you > > use-case, maybe there are better ways to implement what you need. > > > > Le jeu. 12 avr. 2018 à 13:54, Yonghui Zhao <zhaoyong...@gmail.com> a > > écrit : > > > > > Hi, > > > > > > I am upgrading my project from Lucene 4 to 7. > > > > > > FieldCache is removed in lucene 7, DocValue is replacement? > > > > > > But seems DocValue doesn't support random access. > > > > > > I need random access to get some specified field value quickly. > > > > > > So how to solve it? > > > > > >
