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Date: Fri, 22 Oct 2010 17:50:19 -0400 (EDT)
From: "Uwe Schindler (JIRA)" <jira@apache.org>
To: dev@lucene.apache.org
Subject: [jira] Updated: (LUCENE-2719) Re-add SorterTemplate and use it to
 provide fast ArraySorting and replace BytesRefHash sorting
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     [ https://issues.apache.org/jira/browse/LUCENE-2719?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Uwe Schindler updated LUCENE-2719:
----------------------------------

    Attachment: LUCENE-2719.patch

Attached you find the patch. Robert offered to do benchmarks with Automaton.

The patch can be applied to a clean checkout, you no longer need to svn copy old SorterTemplate, as this is a almost complete rewrite.

This patch removes the CHANGES.txt entry for 3.x, as it readds the class. If we don't merge this to 3.x, the CHANGES should be reverted. As Lucene uses Arrays.sort(Object[]) which is slow at other places, I recommend to add it also to 3.x.

Please test the stuff with large -Dtests.multiplier! Maybe also verify my modified quickSort!

> Re-add SorterTemplate and use it to provide fast ArraySorting and replace BytesRefHash sorting
> ----------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-2719
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2719
>             Project: Lucene - Java
>          Issue Type: Improvement
>    Affects Versions: 3.1
>            Reporter: Uwe Schindler
>            Assignee: Uwe Schindler
>             Fix For: 3.1, 4.0
>
>         Attachments: LUCENE-2719.patch
>
>
> This patch adds back an optimized and rewritten SorterTemplate back to Lucene (removed after release of 3.0). It is of use for several components:
> - Automaton: Automaton needs to sort States and other things. Using Arrays.sort() is slow, because it clones internally to ensure stable search. This component is much faster. This patch adds Arrays.sort() replacements in ArrayUtil that work with natural order or using a Comparator<?>. You can choose between quickSort and mergeSort.
> - BytesRefHash uses another QuickSort algorithm without insertionSort for very short ord arrays. This class uses SorterTemplate to provide the same with insertionSort fallback in a very elegant way. Ideally this class can be used everywhere, where the sort algorithm needs to be separated from the underlying data and you can implement a swap() and compare() function (that get slot numbers instead of real values). This also applies to Solr (Yonik?).
> SorterTemplate provides quickSort and mergeSort algorithms. Internally for short arrays, it automatically chooses insertionSort (like JDK's Arrays). The quickSort algorith was copied modified from old BytesRefHash. This new class only shares MergeSort with the original CGLIB SorterTemplate, which is no longer maintained.

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