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https://issues.apache.org/jira/browse/LUCENE-1614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12710827#action_12710827
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Michael McCandless commented on LUCENE-1614:
--------------------------------------------

I wonder if instead of returning -1 when the iteration is done, we should 
return Integer.MAX_VALUE?

This would save CPU for scorers that merge multiple sub-scorers (like 
BooleanScorer/2), because instead of having to check for -1 returned from each 
sub-scorer, they could simply proceed with their normal logic and check for 
Integer.MAX_VALUE just before collecting the doc.  It'd be one fewer if to 
check, per sub-scorer per nextDoc/advance call, which would be a nice savings.

This is what I'm doing on LUCENE-1594.

> Add next() and skipTo() variants to DocIdSetIterator that return the current 
> doc, instead of boolean
> ----------------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-1614
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1614
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Shai Erera
>             Fix For: 2.9
>
>         Attachments: LUCENE-1614.patch
>
>
> See 
> http://www.nabble.com/Another-possible-optimization---now-in-DocIdSetIterator-p23223319.html
>  for the full discussion. The basic idea is to add variants to those two 
> methods that return the current doc they are at, to save successive calls to 
> doc(). If there are no more docs, return -1. A summary of what was discussed 
> so far:
> # Deprecate those two methods.
> # Add nextDoc() and skipToDoc(int) that return doc, with default impl in DISI 
> (calls next() and skipTo() respectively, and will be changed to abstract in 
> 3.0).
> #* I actually would like to propose an alternative to the names: advance() 
> and advance(int) - the first advances by one, the second advances to target.
> # Wherever these are used, do something like '(doc = advance()) >= 0' instead 
> of comparing to -1 for improved performance.
> I will post a patch shortly

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