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From "Adrien Grand (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (LUCENE-4509) Make CompressingStoredFieldsFormat the new default StoredFieldsFormat impl
Date Tue, 13 Nov 2012 15:54:12 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-4509?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Adrien Grand resolved LUCENE-4509.
----------------------------------

       Resolution: Fixed
    Fix Version/s: 4.1

Thanks Robert for your comments, I replaced "documents" with "individual documents" and added
a link to the protobuf docs.

Committed:
 - trunk      r1408762
 - branch 4.x r1408796
                
> Make CompressingStoredFieldsFormat the new default StoredFieldsFormat impl
> --------------------------------------------------------------------------
>
>                 Key: LUCENE-4509
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4509
>             Project: Lucene - Core
>          Issue Type: Wish
>          Components: core/store
>            Reporter: Adrien Grand
>            Assignee: Adrien Grand
>            Priority: Minor
>             Fix For: 4.1
>
>         Attachments: LUCENE-4509.patch, LUCENE-4509.patch
>
>
> What would you think of making CompressingStoredFieldsFormat the new default StoredFieldsFormat?
> Stored fields compression has many benefitsĀ :
>  - it makes the I/O cache work for us,
>  - file-based index replication/backup becomes cheaper.
> Things to know:
>  - even with incompressible data, there is less than 0.5% overhead with LZ4,
>  - LZ4 compression requires ~ 16kB of memory and LZ4 HC compression requires ~ 256kB,
>  - LZ4 uncompression has almost no memory overhead,
>  - on my low-end laptop, the LZ4 impl in Lucene uncompresses at ~ 300mB/s.
> I think we could use the same default parameters as in CompressingCodec :
>  - LZ4 compression,
>  - in-memory stored fields index that is very memory-efficient (less than 12 bytes per
block of compressed docs) and uses binary search to locate documents in the fields data file,
>  - 16 kB blocks (small enough so that there is no major slow down when the whole index
would fit into the I/O cache anyway, and large enough to provide interesting compression ratiosĀ ;
for example Robert got a 0.35 compression ratio with the geonames.org database).
> Any concerns?

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