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https://issues.apache.org/jira/browse/LUCENE-10302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17501358#comment-17501358
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Greg Miller commented on LUCENE-10302:
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As I worked on this a little more, it occurs to me that I think we might want
to implement two separate abstractions here. It feels a bit like overloading
the idea of a PQ builder to provide sorted results.
I started sketching out the idea of a "top-N collector" (naming isn't great...)
that abstracts the idea of just "collecting" the top-n provided elements,
either sorted or unsorted. It encapsulates details about whether-or-not it ever
uses a heap, and just exposes methods to get the top-n, either sorted or
unsorted.
I think it's separately still very useful to have an explicit PQ builder for
cases where the user knows they need a PQ but can build it in bulk up-front.
> PriorityQueue: optimize where we collect then iterate by using O(N) heapify
> ---------------------------------------------------------------------------
>
> Key: LUCENE-10302
> URL: https://issues.apache.org/jira/browse/LUCENE-10302
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: David Smiley
> Priority: Major
> Attachments: LUCENE_PriorityQueue_Builder_with_heapify.patch
>
>
> Looking at LUCENE-8875 (LargeNumHitsTopDocsCollector.java ) I got to
> wondering if there was faster-than O(N*log(N)) way of loading a PriorityQueue
> when we provide a bulk array to initialize the heap/PriorityQueue. It turns
> out there is: the JDK's PriorityQueue supports this in its constructors,
> referring to "This classic algorithm due to Floyd (1964) is known to be
> O(size)" -- heapify() method. There's
> [another|https://www.geeksforgeeks.org/building-heap-from-array/] that may
> or may not be the same; I didn't look too closely yet. I see a number of
> uses of Lucene's PriorityQueue that first collects values and only after
> collecting want to do something with the results (typical / unsurprising).
> This lends itself to a builder pattern that can look similar to
> LargeNumHitsTopDocsCollector in terms of first having an array used like a
> list and then move over to the PriorityQueue if/when it gets full (it may
> not).
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