mmmm, that's not what i see while testing right now. Queries with -one OR -two
return less documents than a either operand does on its own, this is with
LuceneQParser. I haven't done extensive testing since i rarely use boolean
algebra in Lucene or Solr.
> Oops, you're right, I had misremembered --- Solr 1.4.1 "lucene" qp
> handles pure negative fine, it's Solr 1.4.1 _dismax_ that does not.
>
> Although, here's one, not actually related to this thread, that DOESN'T
> work in Solr 1.4.1 lucene query parser. Curious if it's been fixed in
> Solr 3.1.
>
> &defType=lucene&q=-one OR -two
>
> That one does NOT work as expected in solr 1.4.1, although I can't
> explain exactly what it's doing, it's not right. (It returns FEWER
> results than "-one" alone, which can't be right algebraicly). I think.
> So there are still some kinds of negative queries that do weird things.
>
> On 5/17/2011 6:29 PM, Markus Jelsma wrote:
> > Such a negation works just as one would expect.
> >
> > q=*:*
> > <result name="response" numFound="158" start="0">
> >
> > q=*:*&fq=-type:text/html
> > <result name="response" numFound="25" start="0">
> >
> > q=*:*&fq=type:text/html
> > <result name="response" numFound="133" start="0">
> >
> > Well, that adds up , doesn't it ;)
> >
> >> 1. I don't think Solr will re-use the filter cache in that situation,
> >> although I'm not sure. But I comment anyway because, not what you asked
> >> but something else that will trip you up with your example:
> >>
> >> 2. In fact, a pure-negative query like that doesn't work _at all_ in the
> >> default solr/lucene query parser used for 'fq', at least in Solr 1.4.1.
> >> Not sure if it's been improved in 3.1, but I don't think so. It will
> >> always return 0 hits, the solr/lucene query parser can't generate a
> >> proper lucene query from a pure negative query like that.
> >>
> >> To get around this, you can find a variation the query that means the
> >> same thing but isn't that form. Here's a really ugly one I use, with a
> >> nested dismax -- dismax ALSO has trouble with pure negatives, although I
> >> think maybe edismax can handle em? But this weird as heck combo works,
> >> maybe there's a better way.
> >>
> >> NOT _query_:"{!dismax qf=something}history"
> >>
> >> And to come around full circle, I have NO idea what effect nested
> >> queries have on the filter cache. I think that STILL won't re-use the
> >> filter cache.... but I wonder if it'll re-use the _query_ cache for
> >> "history"? I forget even more how the query cache works though.
> >>
> >> On 5/17/2011 6:07 PM, Burton-West, Tom wrote:
> >>> If I have a query with a filter query such as : " q=art&fq=history" and
> >>> then run a second query "q=art&fq=-history", will Solr realize that it
> >>> can use the cached results of the previous filter query "history" (in
> >>> the filter cache) or will it not realize this and have to actually do a
> >>> second filter query against the index for "not history"?
> >>>
> >>> Tom
