[jira] [Commented] (LUCENE-3371) Support for a "SpanAndQuery" / "SpanAllNearQuery"

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

    [ https://issues.apache.org/jira/browse/LUCENE-3371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15469582#comment-15469582 ] 

Trejkaz commented on LUCENE-3371:
---------------------------------

To summarise some investigation I did towards using SpanNotNearQuery, it turns out that this doesn't work, but I can't immediately see why.

My rewrite:

{code}
    @Override
    public SpanQuery rewrite(IndexReader reader) throws IOException
    {
        int nearQueriesCount = nearQueries.size();
        SpanQuery[] notNearClauses = new SpanQuery[nearQueriesCount];
        int pre = inOrder ? slop : 0;
        int post = slop;
        for (int i = 0; i < nearQueriesCount; i++)
        {
            notNearClauses[i] = new SpanNotQuery(mainQuery, nearQueries.get(i), pre, post);
        }
        return new SpanNotQuery(mainQuery, new SpanOrQuery(notNearClauses));
    }
{code}


i.e., for each query, create a "not near" clause, and then subtract the "not near" clauses from the main query clause to get the "near all" result.

This logic is apparently wrong, because this query:

{noformat}
  mainQuery = SpanTerm("content", "a")
  nearQueries = [
    SpanTerm("content", "b"),
    SpanTerm("content", "c")
  ]
  slop = 2,
  inOrder = false
{noformat}

Is expected to match this text:

{noformat}
a x b c x x x a
{noformat}

But instead, it does not match.


> Support for a "SpanAndQuery" / "SpanAllNearQuery"
> -------------------------------------------------
>
>                 Key: LUCENE-3371
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3371
>             Project: Lucene - Core
>          Issue Type: New Feature
>          Components: core/search
>            Reporter: Trejkaz
>
> I would like to parse queries like this:
> {noformat}
> a WITHIN 5 WORDS OF (b AND c)
> {noformat}
> This would match cases where both a b span and a c span are within 5 of the same a span.
> The existing span query classes do not appear to be capable of doing this no matter how they are combined, although replacing the AND with "WITHIN 10 OF" (general rule is to double the first number) at least ensures that no hits are lost (it just returns too many.)
> I'm not sure how the class would work, but it might be like this:
> {code}
>   Query q = new SpanAllNearQuery(a, new SpanQuery[] { b, c }, 5, false);
> {code}
> The difference from SpanNearQuery is that SpanNearQuery considers the entire collection of terms as a single set to be found near each other, whereas this query would consider each of the terms in the array relative to the first.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: dev-help@lucene.apache.org