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From Jonathan Rochkind <>
Subject Re: filter cache and negative filter query
Date Tue, 17 May 2011 22:34:10 GMT
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

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