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https://issues.apache.org/jira/browse/LUCENE-1593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12704232#action_12704232
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Shai Erera commented on LUCENE-1593:
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bq, I'm not sure we can make such a change even in 3.0. Ie, all that's 
"special" about 3.0 is we get to remove deprecated APIs, and begin using Java 
1.5 language features.

I'd like to discuss that in a separate thread, where it will have more 
visibility ... I'm a bit puzzled by what 3.0 means, but it should be discussed 
outside the scope of this issue.

bq. So maybe we can make a new abstract class called AbstractWeight ...

I think we should have an issue handling interfaces deprecation in general for 
2.9, since just deprecating Weight does not solve it. You'd have to deprecate 
Searchable.search* methods which accept Weight, but Searchable is an interface, 
so you might want to deprecate it entirely and create an AbstractSearchable? 
That I think also deserves its own thread, don't you think?

When I thought about the ambiguity that we have in BS2 between score(Collector) 
and next()/skipTo() and the proposal to have topScorer() and scorer(), I 
thought that perhaps we can make the following change (we'd have to solve the 
Weight-interface problem first):
# Define on Weight a score(IndexReader, Collector) API which will be called 
instead of the topScorer() proposal.
# Keep the scorer(IndexReader) API - this should be used for iterating over the 
Scorer.
# Make Scorer.score(Collector) package-private so that it can still be used by 
Weight.score(IndexReader, Collector), but not by anyone else. That will 
effectively remove that API from Scorer, but still keep the impl there so we 
make the least amount of changes to the current Scorers and Weights.
#* We should document that it should not be used, even from inside Lucene's 
code unless there's a really good reason. Everyone, including Lucene should use 
the Weight.score(IndexReader, Collector) API.

That should present a clean and clear API, i.e. topScorer() and scorer() might 
not be understood well, and we'd need to document their usage clearly, and we 
don't have a way to enforce that once topScorer() is called, score(Collector) 
will be the only method that's used and not next()/skipTo().

> Optimizations to TopScoreDocCollector and TopFieldCollector
> -----------------------------------------------------------
>
>                 Key: LUCENE-1593
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1593
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Shai Erera
>             Fix For: 2.9
>
>         Attachments: LUCENE-1593.patch, PerfTest.java
>
>
> This is a spin-off of LUCENE-1575 and proposes to optimize TSDC and TFC code 
> to remove unnecessary checks. The plan is:
> # Ensure that IndexSearcher returns segements in increasing doc Id order, 
> instead of numDocs().
> # Change TSDC and TFC's code to not use the doc id as a tie breaker. New docs 
> will always have larger ids and therefore cannot compete.
> # Pre-populate HitQueue with sentinel values in TSDC (score = Float.NEG_INF) 
> and remove the check if reusableSD == null.
> # Also move to use "changing top" and then call adjustTop(), in case we 
> update the queue.
> # some methods in Sort explicitly add SortField.FIELD_DOC as a "tie breaker" 
> for the last SortField. But, doing so should not be necessary (since we 
> already break ties by docID), and is in fact less efficient (once the above 
> optimization is in).
> # Investigate PQ - can we deprecate insert() and have only 
> insertWithOverflow()? Add a addDummyObjects method which will populate the 
> queue without "arranging" it, just store the objects in the array (this can 
> be used to pre-populate sentinel values)?
> I will post a patch as well as some perf measurements as soon as I have them.

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