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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-7081) Docvalues terms dict should sometimes prefix-compress fixed-length data.
Date Wed, 09 Mar 2016 14:58:41 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-7081?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15187199#comment-15187199
] 

Michael McCandless commented on LUCENE-7081:
--------------------------------------------

+1, nice!

> Docvalues terms dict should sometimes prefix-compress fixed-length data.
> ------------------------------------------------------------------------
>
>                 Key: LUCENE-7081
>                 URL: https://issues.apache.org/jira/browse/LUCENE-7081
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Robert Muir
>         Attachments: LUCENE-7081.patch
>
>
> For Sorted/SortedSet types, we encode ordinals and a term dictionary (similar to old
lucene 3 term dictionary).
> Originally we had no prefix compression, so we "save space" in the fixed-width case by
avoiding addressing, we can just use multiplication: https://github.com/apache/lucene-solr/blob/master/lucene/core/src/java/org/apache/lucene/codecs/lucene54/Lucene54DocValuesConsumer.java#L423-L425

> But it means no compression whatsoever of the actual bytes, even if values are enormous,
I don't think its necessarily a good tradeoff. The lack of prefix compression can become much
more magnified now that we have fixed width 128-bit point types in the sandbox...



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