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https://issues.apache.org/jira/browse/LUCENE-1614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12714298#action_12714298
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Shai Erera commented on LUCENE-1614:
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Mike, I think we may have relaxed the policy of docID() a bit too much. IMO, it
should be clear what this method returns, and saying that it should return any
doc ID which is smaller than the first available, or NO_MORE_DOCS if it knows
there are not docs in the set, is problematic.
Consider the code in BS2 which checks if it should call nextDoc() before the
while loop (the score(Collector, int) method). If a DISI decided to return '2'
simply because the first doc available is '3', then we may incorrectly collect
'2'.
So I say we relax the policy in this way: "an implementation can return -1 if
it knows the iterator is not exhausted, or NO_MORE_DOCS otherwise".
> 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, LUCENE-1614.patch, LUCENE-1614.patch,
> LUCENE-1614.patch, LUCENE-1614.patch, LUCENE-1614.patch, 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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