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https://issues.apache.org/jira/browse/LUCENE-2810?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12970796#action_12970796
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Simon Willnauer commented on LUCENE-2810:
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bq. For instance, perhaps it is possible to have a part of storage that 
contains the set of unique values for all the fields and the document field 
value simply contains a reference (could be as small as a few bits depending on 
the number of uniq. items) to that value instead of having a full copy. 

Grant, how would that be different to DocValues DerefVarBytes variant really. I 
don't think that the Stored Fields feature in lucene should be very much 
extended in its semantics. if somebody wants to use BDB or something else to 
store the values fine, other than that they should really use docValues and 
specialize for a certain usecase. Stored Fields support in Codec is far away 
IMO since we need to build quiet some API on top of the existing codec API to 
consume entire documents. Yet, that said - help is very welcome in the 
docValues branch....


simon

> Stored Fields Compression
> -------------------------
>
>                 Key: LUCENE-2810
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2810
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Store
>            Reporter: Grant Ingersoll
>            Assignee: Grant Ingersoll
>
> In some cases (logs, HTML pages w/ boilerplate, etc.), the stored fields for 
> documents contain a lot of redundant information and end up wasting a lot of 
> space across a large collection of documents.  For instance, simply 
> compressing a typical log file often results in > 75% compression rates.  We 
> should explore mechanisms for applying compression across all the documents 
> for a field (or fields) while still maintaining relatively fast lookup (that 
> being said, in most logging applications, fast retrieval of a given event is 
> not always critical.)  For instance, perhaps it is possible to have a part of 
> storage that contains the set of unique values for all the fields and the 
> document field value simply contains a reference (could be as small as a few 
> bits depending on the number of uniq. items) to that value instead of having 
> a full copy.  Extending this, perhaps we can leverage some existing 
> compression capabilities in Java to provide this as well.  
> It may make sense to implement this as a Directory, but it might also make 
> sense as a Codec, if and when we have support for changing storage Codecs.

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