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From "Ning Li (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1541) Trie range - make trie range indexing more flexible
Date Fri, 20 Feb 2009 01:54:01 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12675212#action_12675212
] 

Ning Li commented on LUCENE-1541:
---------------------------------

If you are *really* concerned with the additional loop and the additional array allocations,
a long can be used to represent the precision steps. For example, precision steps 2-2-2-2-8-8-8-8-8-16
are represented as 0x80008080808080aa. Then bitCount, shift and numberOfTrailingZeros can
be used to determine the length of the trie array and the individual precision steps. Hmm,
we still have to support Java 1.4?

> Trie range - make trie range indexing more flexible
> ---------------------------------------------------
>
>                 Key: LUCENE-1541
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1541
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: contrib/*
>    Affects Versions: 2.9
>            Reporter: Ning Li
>            Assignee: Uwe Schindler
>            Priority: Minor
>             Fix For: 2.9
>
>         Attachments: LUCENE-1541.patch
>
>
> In the current trie range implementation, a single precision step is specified. With
a large precision step (say 8), a value is indexed in fewer terms (8) but the number of terms
for a range can be large. With a small precision step (say 2), the number of terms for a range
is smaller but a value is indexed in more terms (32).
> We want to add an option that different precision steps can be set for different precisions.
An expert can use this option to keep the number of terms for a range small and at the same
time index a value in a small number of terms. See the discussion in LUCENE-1470 that results
in this issue.

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