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Posted to dev@lucene.apache.org by "Varun Thacker (JIRA)" <ji...@apache.org> on 2014/05/20 15:26:38 UTC
[jira] [Updated] (LUCENE-5688) NumericDocValues fields with sparse
data can be compressed better
[ https://issues.apache.org/jira/browse/LUCENE-5688?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Varun Thacker updated LUCENE-5688:
----------------------------------
Attachment: LUCENE-5688.patch
Here is a quick patch. Wanted to get some feedback on the approach.
When I run the showIndexBloat method without the SPARSE_COMPRESSED changes, this is the size of the docValues data -
{noformat}
-rw-r--r-- 1 varun wheel 9.9M May 20 18:28 _a_Lucene45_0.dvd
-rw-r--r-- 1 varun wheel 312B May 20 18:28 _a_Lucene45_0.dvm
{noformat}
With the SPARSE_COMPRESSED changes
{noformat}
-rw-r--r-- 1 varun wheel 2.7M May 20 18:51 _a_Lucene45_0.dvd
-rw-r--r-- 1 varun wheel 352B May 20 18:51 _a_Lucene45_0.dvm
{noformat}
> NumericDocValues fields with sparse data can be compressed better
> ------------------------------------------------------------------
>
> Key: LUCENE-5688
> URL: https://issues.apache.org/jira/browse/LUCENE-5688
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Varun Thacker
> Priority: Minor
> Attachments: LUCENE-5688.patch
>
>
> I ran into this problem where I had a dynamic field in Solr and indexed data into lots of fields. For each field only a few documents had actual values and the remaining documents the default value ( 0 ) got indexed. Now when I merge segments, the index size jumps up.
> For example I have 10 segments - Each with 1 DV field. When I merge segments into 1 that segment will contain all 10 DV fields with lots if 0s.
> This was the motivation behind trying to come up with a compression for a use case like this.
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