[jira] [Created] (LUCENE-7638) Optimize graph query produced by QueryBuilder

["Jim Ferenczi (JIRA)" <ji...@apache.org>]

Jim Ferenczi created LUCENE-7638:
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             Summary: 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


The QueryBuilder now 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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