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From "Mark Miller (JIRA)" <>
Subject [jira] Commented: (LUCENE-2006) Optimization for FieldDocSortedHitQueue
Date Fri, 23 Oct 2009 22:47:59 GMT


Mark Miller commented on LUCENE-2006:

Okay Uwe -

I took a 2 GB zipped Wiki dump and used a SkipDocTask to create four unique indices of 64,000
docs each.

Then I ran a search matching all docs and sorting on title, taking the average of 1000 runs
and recording that overage over a few times for each method.

I tried topn's of 10, 100, and 1000.

I couldn't measure a meaningful difference one way or the other. Lets do it.

> Optimization for FieldDocSortedHitQueue
> ---------------------------------------
>                 Key: LUCENE-2006
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>    Affects Versions: 3.0
>            Reporter: Uwe Schindler
>            Assignee: Uwe Schindler
>             Fix For: 3.0
>         Attachments: LUCENE-2006.patch
> When updating core for generics,  I found the following as a optimization of FieldDocSortedHitQueue:
> All FieldDoc values are Compareables (also the score or docid, if they
> appear as SortField in a MultiSearcher or ParallelMultiSearcher). The code
> of lessThan seems very ineffective, as it has a big switch statement on the
> SortField type, then casts the value to the underlying numeric type Object,
> calls Number.xxxValue() & co for it and then compares manually. As
> j.l.Number is itself Comparable, I see no reason to do this. Just call
> compareTo on the Comparable interface and we are happy. The big deal is that
> it prevents casting and the two method calls xxxValue(), as Number.compareTo
> works more efficient internally.
> The only special cases are String sort, where the Locale may be used and the
> score sorting which is backwards. But these are two if statements instead of
> the whole switch.
> I had not tested it now for performance, but in my opinion it should be
> faster for MultiSearchers. All tests still pass (because they should).

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