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From "Robert Muir (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-7371) BKDReader could compress values better
Date Mon, 18 Jul 2016 15:24:20 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-7371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15382452#comment-15382452
] 

Robert Muir commented on LUCENE-7371:
-------------------------------------

I think [~mikemccand] may have upgraded his operating system.

> BKDReader could compress values better
> --------------------------------------
>
>                 Key: LUCENE-7371
>                 URL: https://issues.apache.org/jira/browse/LUCENE-7371
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Adrien Grand
>            Assignee: Adrien Grand
>            Priority: Minor
>             Fix For: master (7.0), 6.2
>
>         Attachments: LUCENE-7371.patch, LUCENE-7371.patch, LUCENE-7371.patch
>
>
> For compressing values, BKDReader only relies on shared prefixes in a block. We could
probably easily do better. For instance there are only 256 possible values for the first byte
of the dimension that the values are sorted by, yet we use a block size of 1024. So by using
something simple like run-length compression we could save 6 bits per value on average.



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