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https://issues.apache.org/jira/browse/LUCENE-5205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14027583#comment-14027583
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Paul Elschot commented on LUCENE-5205:
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bq. How can I help?
In case you're familiar with git/github we could cooperate at github, otherwise
we can post patches.
Shall I open another issue for this?
Could you take a look at the javadocs of LUCENE-5627 ? I think that would help
in understanding the connections to be made.
bq. What would the syntax of a query look like?
That is an open question to me. For the label-fragment joins this might work
for example to find a label l1 in the lb: field that has a fragment in the fr:
field containing f1:
lb:[ l1 fr:f1]
This would add the join from the fr: field to the lb: field automatically.
f1 might also be a nested query with brackets itself.
The allowed distance in the lb: field should normally be zero, the matches
should be at the same label position.
Basically that boils down to using something like SpanWithinQuery in the label
field.
There are also some corner cases. For example this could make sense:
lb:[ l1 fr:]
to query for labels l1 that have a non empty fragment in the fr: field.
The other way around:
fr:[ f1 lb:]
does not make sense because labels are never empty.
For the label tree queries have a look here
http://en.wikipedia.org/wiki/XPath#Axis_specifiers to get an idea of the
possibilities.
The attribute axis is not needed, in the positional joins XML attributes and
their values are indexed as fragments in separate fields.
I don't know much about namespaces, so for the moment they are not needed
either.
All the other axes might be implemented here, we could start by the ones I
mentioned above: child by name, child by index, parent, descendant-or -self.
The slash / is used by XPath for the child axis, and here it is in use for
regular expressions, so some other syntax might be needed here.
> [PATCH] SpanQueryParser with recursion, analysis and syntax very similar to
> classic QueryParser
> -----------------------------------------------------------------------------------------------
>
> Key: LUCENE-5205
> URL: https://issues.apache.org/jira/browse/LUCENE-5205
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/queryparser
> Reporter: Tim Allison
> Labels: patch
> Fix For: 4.9
>
> Attachments: LUCENE-5205-cleanup-tests.patch,
> LUCENE-5205-date-pkg-prvt.patch, LUCENE-5205.patch.gz, LUCENE-5205.patch.gz,
> LUCENE-5205_dateTestReInitPkgPrvt.patch,
> LUCENE-5205_improve_stop_word_handling.patch,
> LUCENE-5205_smallTestMods.patch, LUCENE_5205.patch,
> SpanQueryParser_v1.patch.gz, patch.txt
>
>
> This parser extends QueryParserBase and includes functionality from:
> * Classic QueryParser: most of its syntax
> * SurroundQueryParser: recursive parsing for "near" and "not" clauses.
> * ComplexPhraseQueryParser: can handle "near" queries that include multiterms
> (wildcard, fuzzy, regex, prefix),
> * AnalyzingQueryParser: has an option to analyze multiterms.
> At a high level, there's a first pass BooleanQuery/field parser and then a
> span query parser handles all terminal nodes and phrases.
> Same as classic syntax:
> * term: test
> * fuzzy: roam~0.8, roam~2
> * wildcard: te?t, test*, t*st
> * regex: /\[mb\]oat/
> * phrase: "jakarta apache"
> * phrase with slop: "jakarta apache"~3
> * default "or" clause: jakarta apache
> * grouping "or" clause: (jakarta apache)
> * boolean and +/-: (lucene OR apache) NOT jakarta; +lucene +apache -jakarta
> * multiple fields: title:lucene author:hatcher
>
> Main additions in SpanQueryParser syntax vs. classic syntax:
> * Can require "in order" for phrases with slop with the \~> operator:
> "jakarta apache"\~>3
> * Can specify "not near": "fever bieber"!\~3,10 ::
> find "fever" but not if "bieber" appears within 3 words before or 10
> words after it.
> * Fully recursive phrasal queries with \[ and \]; as in: \[\[jakarta
> apache\]~3 lucene\]\~>4 ::
> find "jakarta" within 3 words of "apache", and that hit has to be within
> four words before "lucene"
> * Can also use \[\] for single level phrasal queries instead of " as in:
> \[jakarta apache\]
> * Can use "or grouping" clauses in phrasal queries: "apache (lucene solr)"\~3
> :: find "apache" and then either "lucene" or "solr" within three words.
> * Can use multiterms in phrasal queries: "jakarta\~1 ap*che"\~2
> * Did I mention full recursion: \[\[jakarta\~1 ap*che\]\~2 (solr~
> /l\[ou\]\+\[cs\]\[en\]\+/)]\~10 :: Find something like "jakarta" within two
> words of "ap*che" and that hit has to be within ten words of something like
> "solr" or that "lucene" regex.
> * Can require at least x number of hits at boolean level: "apache AND (lucene
> solr tika)~2
> * Can use negative only query: -jakarta :: Find all docs that don't contain
> "jakarta"
> * Can use an edit distance > 2 for fuzzy query via SlowFuzzyQuery (beware of
> potential performance issues!).
> Trivial additions:
> * Can specify prefix length in fuzzy queries: jakarta~1,2 (edit distance =1,
> prefix =2)
> * Can specifiy Optimal String Alignment (OSA) vs Levenshtein for distance
> <=2: (jakarta~1 (OSA) vs jakarta~>1(Levenshtein)
> This parser can be very useful for concordance tasks (see also LUCENE-5317
> and LUCENE-5318) and for analytical search.
> Until LUCENE-2878 is closed, this might have a use for fans of SpanQuery.
> Most of the documentation is in the javadoc for SpanQueryParser.
> Any and all feedback is welcome. Thank you.
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