Thanks Erick. As indexed is not necessary, and docValues is more efficient than stored fields for function queries, so we shall go with the following:
3) indexed=false, stored=false, docValues=true. Is my understanding correct? Best, Wei On Wed, Nov 4, 2020 at 5:24 AM Erick Erickson <erickerick...@gmail.com> wrote: > You don’t need to index the field for function queries, see: > https://lucene.apache.org/solr/guide/8_6/docvalues.html. > > Function queries, as opposed to sorting, faceting and grouping are > evaluated at search time where the > search process is already parked on the document anyway, so answering the > question “for doc X, what > is the value of field Y” to compute the score. DocValues are still more > efficient I think, although I > haven’t measured explicitly... > > For sorting, faceting and grouping, it’s a much different story. Take > sorting. You have to ask > “for field Y, what’s the value in docX and docZ?”. Say you’re parked on > docX. Doc Z is long gone > and getting the value for field Y much more expensive. > > Also, docValues will not increase memory requirements _unless used_. > Otherwise they’ll > just sit there on disk. They will certainly increase disk space whether > used or not. > > And _not_ using docValues when you facet, group or sort will also > _certainly_ increase > your heap requirements since the docValues structure must be built on the > heap rather > than be in MMapDirectory space. > > Best, > Erick > > > > On Nov 4, 2020, at 5:32 AM, uyilmaz <uyil...@vivaldi.net.INVALID> wrote: > > > > Hi, > > > > I'm by no means expert on this so if anyone sees a mistake please > correct me. > > > > I think you need to index this field, since boost functions are added to > the query as optional clauses ( > https://lucene.apache.org/solr/guide/6_6/the-dismax-query-parser.html#TheDisMaxQueryParser-Thebf_BoostFunctions_Parameter). > It's like boosting a regular field by putting ^2 next to it in a query. > Storing or enabling docValues will unnecesarily consume space/memory. > > > > On Tue, 3 Nov 2020 16:10:50 -0800 > > Wei <weiwan...@gmail.com> wrote: > > > >> Hi, > >> > >> I have a couple of primitive single value numeric type fields, their > >> values are used in boosting functions, but not used in sort/facet. or in > >> returned response. Should I use docValues for them in the schema? I > can > >> think of the following options: > >> > >> 1) indexed=true, stored=true, docValues=false > >> 2) indexed=true, stored=false, docValues=true > >> 3) indexed=false, stored=false, docValues=true > >> > >> What would be the performance implications for these options? > >> > >> Best, > >> Wei > > > > > > -- > > uyilmaz <uyil...@vivaldi.net> > >
