[jira] [Commented] (LUCENE-6863) Store sparse doc values more efficiently

["ASF subversion and git services (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-6863?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14993625#comment-14993625 ] 

ASF subversion and git services commented on LUCENE-6863:
---------------------------------------------------------

Commit 1712957 from [~jpountz] in branch 'dev/trunk'
[ https://svn.apache.org/r1712957 ]

LUCENE-6863: Optimized storage requirements of doc values fields when less than 1% of documents have a value.

> Store sparse doc values more efficiently
> ----------------------------------------
>
>                 Key: LUCENE-6863
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6863
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Adrien Grand
>            Assignee: Adrien Grand
>         Attachments: LUCENE-6863.patch, LUCENE-6863.patch, LUCENE-6863.patch
>
>
> For both NUMERIC fields and ordinals of SORTED fields, we store data in a dense way. As a consequence, if you have only 1000 documents out of 1B that have a value, and 8 bits are required to store those 1000 numbers, we will not require 1KB of storage, but 1GB.
> I suspect this mostly happens in abuse cases, but still it's a pity that we explode storage requirements. We could try to detect sparsity and compress accordingly.



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