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From "Uwe Schindler (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (LUCENE-4839) Sorter API: Use TimSort to sort doc IDs and postings lists
Date Sat, 16 Mar 2013 15:04:13 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13604283#comment-13604283
] 

Uwe Schindler edited comment on LUCENE-4839 at 3/16/13 3:03 PM:
----------------------------------------------------------------

Nice! Why do we need the private inner class TimSort?

I would be happy to also add the timSort algorithm to ArrayUtils and CollectionUtils. Its
just adding some convenience methods using the already existing SorterTemplates for arrays
and collections.
The bonus would be: The extensive random tests in TestArrayUtils and TestCollectionUtils could
be used for timSort, too (their existence is the reason why there is no TestSorterTemplate
class in current code).
                
      was (Author: thetaphi):
    Nice! Why do we need the private inner class TimSort?

I would be happy to also add the timSort algorithm to ArrayUtils and CollectionUtils. Its
just adding some convenience methods using the already existing SorterTemplates for arrays
and collections.
                  
> Sorter API: Use TimSort to sort doc IDs and postings lists
> ----------------------------------------------------------
>
>                 Key: LUCENE-4839
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4839
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Adrien Grand
>            Assignee: Adrien Grand
>            Priority: Minor
>         Attachments: LUCENE-4839.patch
>
>
> TimSort (http://svn.python.org/projects/python/trunk/Objects/listsort.txt, used by python
and Java's Arrays.sort(Object[]) in particular) is a sorting algorithm that performs very
well on partially-sorted data. Indeed, with TimSort, sorting an array which is in reverse
order or a finite concatenation of sorted arrays is a linear operation (instead of O(n ln(n))).
> The sorter API could benefit from this algorithm when using Sorter.REVERSE_DOCS or merging
several sorted readers for example.

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