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https://issues.apache.org/jira/browse/LUCENE-7638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15826085#comment-15826085
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Jim Ferenczi commented on LUCENE-7638:
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Thanks for taking a look @mattweber and [~mikemccand]
{quote}
Can this handle "side paths on side paths" graph structure (I think you called
this "nested multi-term synonyms")? While no analysis chain can naturally
produce this today (that I know of!), the TokenStream attributes can easily
express it. And you could imagine it happening in the future, e.g. if you use
Kuromoji tokenizer or WordDelimiterGraphFilter followed by a SynonymGraphFilter
(except we'd need to e.g. use the synonym graph filter from LUCENE-5012, which
can correctly consume a graph). If this is expected to work maybe we should add
a test case showing that?
{quote}
I'll add a test case because it's expected to work ;) . This is also the reason
why this patch does not produce {code}PhraseQuery{code} for synonyms. For
simple "side paths" this is easy to do but we would need to switch to Span
queries for "side paths on side paths" so I though that it could be done in
another issue.
{quote}
It seems like you don't need to be using Term here, except at the end to pass
to the newXXXQuery, since everything is in a single field here, and we are
hoping to move away from Term entirely (LUCENE-7632)?
{quote}
Thanks, I'll simplify the patch.
{quote}
Holes are challenging for graph token streams ... can you add a test case that
encounters holes, e.g. simulated StopFilter? There are at least two "fun"
cases: a hole that cuts the graph entirely into two partitions, and a synonym
spanning over a hole ... CannedTokenStream is useful for feeding such
"interesting" cases.
{quote}
I though that holes would not be a problem for boolean queries but now I am not
sure. I'll test that.
{quote}
The Path.id seems to be used only for tie-breaking on compare, not for lookup
in the TreeSet as the comment suggests?
{quote}
The comment is misleading. It is needed because I use
{code}TreeSet#remove{code} which uses compare to check object equality. So the
{code}Path.id{code} is the unique identifier for the path.
> Optimize graph query produced by QueryBuilder
> ---------------------------------------------
>
> Key: LUCENE-7638
> URL: https://issues.apache.org/jira/browse/LUCENE-7638
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Jim Ferenczi
> Attachments: LUCENE-7638.patch
>
>
> The QueryBuilder creates a graph query when the underlying TokenStream
> contains token with PositionLengthAttribute greater than 1.
> These TokenStreams are in fact graphs (lattice to be more precise) where
> synonyms can span on multiple terms.
> Currently the graph query is built by visiting all the path of the graph
> TokenStream. For instance if you have a synonym like "ny, new york" and you
> search for "new york city", the query builder would produce two pathes:
> "new york city", "ny city"
> This can quickly explode when the number of multi terms synonyms increase.
> The query "ny ny" for instance would produce 4 pathes and so on.
> For boolean queries with should or must clauses it should be more efficient
> to build a boolean query that merges all the intersections in the graph. So
> instead of "new york city", "ny city" we could produce:
> "+((+new +york) ny) +city"
> The attached patch is a proposal to do that instead of the all path solution.
> The patch transforms multi terms synonyms in graph query for each
> intersection in the graph. This is not done in this patch but we could also
> create a specialized query that gives equivalent scores to multi terms
> synonyms like the SynonymQuery does for single term synonyms.
> For phrase query this patch does not change the current behavior but we could
> also use the new method to create optimized graph SpanQuery.
> [~mattweber] I think this patch could optimize a lot of cases where multiple
> muli-terms synonyms are present in a single request. Could you take a look ?
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