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From "ASF subversion and git services (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-7121) BKDWriter should not store ords when documents are single valued
Date Sun, 20 Mar 2016 13:18:33 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-7121?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15203290#comment-15203290
] 

ASF subversion and git services commented on LUCENE-7121:
---------------------------------------------------------

Commit cc01ba39cd98bf2274f2ac98c44bcd60028697b3 in lucene-solr's branch refs/heads/branch_6x
from Mike McCandless
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=cc01ba3 ]

LUCENE-7121: don't write ord for single-valued points, saving 4 bytes per point


> BKDWriter should not store ords when documents are single valued
> ----------------------------------------------------------------
>
>                 Key: LUCENE-7121
>                 URL: https://issues.apache.org/jira/browse/LUCENE-7121
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>             Fix For: master, 6.1
>
>         Attachments: LUCENE-7121.patch
>
>
> Since we now have stats for points fields, it's easy to know up front whether the field
you are about to build a BKD tree for is single valued or not.
> If it is single valued, we can optimize space by not storing the ordinal to identify
a point, since its docID also uniquely identifies it.
> This saves 4 bytes per point, which for the 1D case is non-trivial (12 bytes down to
8 bytes per doc), and even for the 2D case is good reduction (16 bytes down to 12 bytes per
doc).
> This is an optimization ... I won't push it into 6.0.



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