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From "Shai Erera (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1652) Enhancements to Scorers following the changes to DocIdSetIterator
Date Tue, 23 Jun 2009 20:11:07 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1652?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12723282#action_12723282
] 

Shai Erera commented on LUCENE-1652:
------------------------------------

It looks like everything we mentioned here was taken care of as part of LUCENE-1614 and LUCENE-1630.

Over in LUCENE-1630 we discussed TopScorer. Do you still think it's something we should do.
If so, we can do it as part of this issue.

I don't remember anything else that came up in the latest issues that we didn't list here.
Do you?

> Enhancements to Scorers following the changes to DocIdSetIterator
> -----------------------------------------------------------------
>
>                 Key: LUCENE-1652
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1652
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Shai Erera
>             Fix For: 3.0
>
>
> In LUCENE-1614, we changed the semantics of DocIdSetIterator's methods to return a sentinel
NO_MORE_DOCS (= Integer.MAX_VALUE) when the iterator has exhausted. Due to backward compatibility
issues, we couldn't implement that semantics in doc(). Therefore this issue, which can be
introduced in 3.0 only will:
> # Implement the new semantics in all extending classes, such that doc() will return NO_MORE_DOCS
when the iterator has exhausted.
> # Change BooleanScorer to take advantage of that by removing sub.done from SubScorer
and operate under the assumption that NO_MORE_DOCS is larger than any doc ID (Integer.MAX_VALUE).
> # Change ConjunctionScorer to operate under the same assumptions and remove 'more'.
> # Change ReqExclScorer to not rely on reqScorer in doc(), since the latter may be null.
> # Make more changes to ConjunctionScorer's init() and remove 'firstTime' to improve the
performance of nextDoc(), score(), advance().
> # Add start()/finish() to DISI?
> A snippet from LUCENE-1614 regarding the change in BooleanScorer
> {code}
> int doc = sub.done ? -1 : scorer.doc();
> while (!sub.done && doc < end) {
>   sub.collector.collect(doc);
>   doc = scorer.nextDoc();
>   sub.done = doc < 0;
> }
> {code}
> To this:
> {code}
> int doc = scorer.doc();
> while (doc < end) {
>   sub.collector.collect(doc);
>   doc = scorer.nextDoc();
> }
> {code}
> And in ConjunctionScorer, change this:
> {code}
> while (more && (firstScorer=scorers[first]).doc() < (lastDoc=lastScorer.doc()))
{
>   more = firstScorer.advance(lastDoc) >= 0;
>   lastScorer = firstScorer;
>   first = (first == (scorers.length-1)) ? 0 : first+1;
> }
> return more;
> {code}
> To this:
> {code}
> while ((firstScorer=scorers[first]).doc() < (lastDoc=lastScorer.doc())) {
>   firstScorer.advance(lastDoc);
>   lastScorer = firstScorer;
>   first = (first == (scorers.length-1)) ? 0 : first+1;
> }
> return lastDoc != DOC_SENTINEL;
> {code}

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