[jira] [Commented] (LUCENE-3892) Add a useful intblock postings format (eg, FOR, PFOR, PFORDelta, Simple9/16/64, etc.)

["Michael McCandless (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-3892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13245374#comment-13245374 ] 

Michael McCandless commented on LUCENE-3892:
--------------------------------------------

The proposal at
http://www.google-melange.com/gsoc/proposal/review/google/gsoc2012/billybob/1
looks great!  Some initial feedback:

  * There are actually more than 2 codecs (eg we also have Lucene3x,
    SimpleText, sep/intblock (abstract), random codecs/postings
    formats for testing...), but our default codec now is Lucene40.

  * I think you can use the existing abstract sep/intblock classes
    (ie, they implement layers like FieldsProducer/Consumer...), and
    then you can "just" implement the required methods (eg to
    encode/decode one int[] block).

  * We may need to tune the skipper settings, based on profiling
    results from skip-intensive (Phrase, And) queries... since it's
    currently geared towards single-doc-at-once encoding.  I don't think
    we should try to make a new skipper impl here... (there is a separate
    issue for that).

  * Maybe explore the combination of pulsing and PForDelta codecs;
    seems like the combination of those two could be important, since
    for low docFreq terms, retrieving the docs is now more
    expensive...

                
> Add a useful intblock postings format (eg, FOR, PFOR, PFORDelta, Simple9/16/64, etc.)
> -------------------------------------------------------------------------------------
>
>                 Key: LUCENE-3892
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3892
>             Project: Lucene - Java
>          Issue Type: Improvement
>            Reporter: Michael McCandless
>              Labels: gsoc2012, lucene-gsoc-12
>             Fix For: 4.0
>
>
> On the flex branch we explored a number of possible intblock
> encodings, but for whatever reason never brought them to completion.
> There are still a number of issues opened with patches in different
> states.
> Initial results (based on prototype) were excellent (see
> http://blog.mikemccandless.com/2010/08/lucene-performance-with-pfordelta-codec.html
> ).
> I think this would make a good GSoC project.

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