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https://issues.apache.org/jira/browse/LUCENE-3892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13431709#comment-13431709
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Adrien Grand commented on LUCENE-3892:
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The comment you added in 1371011 on the value of {{BLOCK_SIZE}} caught my
attention: I think that BLOCK_SIZE should be at least 64 with PackedInts
encoding/decoding since these conversions are long-aligned (I backported your
two commits and added a comment about this). For example, the {{PACKED}} 7-bits
encoder cannot encode less than 64 values in one iteration.
In case someone would really want to use smaller block sizes (eg. 32), I think
it should still perform pretty well if {{acceptableOverheadRatio >= ~25%}} (in
that case, all bits-per-value in the [1-24] range either use a
{{PACKED_SINGLE_BLOCK}} encoder or an 8-bits, 16-bits or 24-bits {{PACKED}}
decoder).
Do we plan to make the block size configurable?
> 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 - Core
> Issue Type: Improvement
> Reporter: Michael McCandless
> Labels: gsoc2012, lucene-gsoc-12
> Fix For: 4.1
>
> Attachments: LUCENE-3892-BlockTermScorer.patch,
> LUCENE-3892-blockFor&hardcode(base).patch,
> LUCENE-3892-blockFor&packedecoder(comp).patch,
> LUCENE-3892-blockFor-with-packedints-decoder.patch,
> LUCENE-3892-blockFor-with-packedints-decoder.patch,
> LUCENE-3892-blockFor-with-packedints.patch, LUCENE-3892-bulkVInt.patch,
> LUCENE-3892-direct-IntBuffer.patch, LUCENE-3892-for&pfor-with-javadoc.patch,
> LUCENE-3892-handle_open_files.patch, LUCENE-3892-non-specialized.patch,
> LUCENE-3892-pfor-compress-iterate-numbits.patch,
> LUCENE-3892-pfor-compress-slow-estimate.patch, LUCENE-3892_for_byte[].patch,
> LUCENE-3892_for_int[].patch, LUCENE-3892_for_unfold_method.patch,
> LUCENE-3892_pfor_unfold_method.patch, LUCENE-3892_pulsing_support.patch,
> LUCENE-3892_settings.patch, LUCENE-3892_settings.patch
>
>
> 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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