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https://issues.apache.org/jira/browse/LUCENE-1593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12706373#action_12706373
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Michael McCandless commented on LUCENE-1593:
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Patch looks good! I can confirm that all tests pass. (Though the back-compat
tag has moved forward -- I just carried that part of the patch forward).
Thanks Shai.
Some small comments:
* No need to call out the API change to HitQueue in CHANGES.txt
(it's package private)
* Can't the out-of-order TFC classes do the "pre-populate pqueue w/
sentinel" optimization?
* There are some leftover javadocs references to
Query#scoresDosInOrder (in at least TSDC)
* I don't think we should this yet, but..: it'd be conceivably
possible at indexing time to record if a given field ever uses the
sentinel value for that field's type. If it doesn't, we can also
safely pre-fill the queue w/ sentinels even for in-order scoring.
(There are many barriers to doing this optimization today in
Lucene).
> 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, LUCENE-1593.patch, 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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