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From Shai Erera <ser...@gmail.com>
Subject Re: NearSpansOrdered semantics
Date Wed, 03 Sep 2014 18:23:46 GMT
Thanks Hoss, this is very useful information, especially
FieldMaskingSpanQuery :).

So according to those issues, it seems others also think that end1 <= end2
is also a "correct" behavior of SNQ (in case ordered=true, and
start1==start2). Was there a reason these issues were not resolved (e.g.
LUCENE-3120)? I'm asking if there was additional discussion where people
raised objections against this, or was it just a matter of lack of
time/focus?

Shai


On Wed, Sep 3, 2014 at 8:47 PM, Chris Hostetter <hossman_lucene@fucit.org>
wrote:

> : I then implemented a variation of a span query which I call
> SpanWithinQuery
> : which allows me to search for "fox WITHIN nickname". The way it's
> : implemented is a SpanNearQuery on annot:nick and annot:/nick, and
> whenever
> : a match is found for 'fox', it makes sure that the position falls within
> : the range of the nick annotation. Quite simple.
>
> FWIW: i think what you are describing is just a special case of
> FieldMaskingSpanQuery, might save you some custom code -- but that's a
> tangent.
>
> : If you forget about all the preface I wrote above, I have a basic
> question
> : about the semantics of SNQ. I tried a simple case -- SNQ("fox", "fox")
> and
> : I get 0 results. Is this a bug in SNQ itself, or it's not built to find
> : spans that are identical in their start/end positions, and I should use
> : another variant of SpanQuery?
>
> I'm not lookin at the code, and i'ts been a looooong while since i thouht
> about phrases/spans in depth, but i seem to recall this being a known
> aspect of the behavior ... similar to how PhraseQuery behaves i think?
>
> since you have "ordered=true" then the 2nd span must come *after* the
> first span, and "after" is defined based on the end position of hte spans
> (aparently?)
>
> You'll find a couple issues in jira (both closed and open) discussing what
> the "right" behavior of SpanNearQuery should be.  Some particularly
> on-point issues based on a quick skim...
>
> https://issues.apache.org/jira/browse/LUCENE-3120
> https://issues.apache.org/jira/browse/LUCENE-3371
> https://issues.apache.org/jira/browse/LUCENE-3229
>
>
> -Hoss
> http://www.lucidworks.com/
>
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