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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-2723) Speed up Lucene's low level bulk postings read API
Date Wed, 03 Nov 2010 12:11:23 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12927824#action_12927824
] 

Michael McCandless commented on LUCENE-2723:
--------------------------------------------

Ugh, sorry -- that GatherFieldValues isn't going to be committed; you can discard all mods
under contrib/benchmark in the patch.

And we'll have to fix the copyOfRange before committing.  I'll stuck a nocommit on it :)

> Speed up Lucene's low level bulk postings read API
> --------------------------------------------------
>
>                 Key: LUCENE-2723
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2723
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>             Fix For: 4.0
>
>         Attachments: LUCENE-2723.patch, LUCENE-2723.patch
>
>
> Spinoff from LUCENE-1410.
> The flex DocsEnum has a simple bulk-read API that reads the next chunk
> of docs/freqs.  But it's a poor fit for intblock codecs like FOR/PFOR
> (from LUCENE-1410).  This is not unlike sucking coffee through those
> tiny plastic coffee stirrers they hand out airplanes that,
> surprisingly, also happen to function as a straw.
> As a result we see no perf gain from using FOR/PFOR.
> I had hacked up a fix for this, described at in my blog post at
> http://chbits.blogspot.com/2010/08/lucene-performance-with-pfordelta-codec.html
> I'm opening this issue to get that work to a committable point.
> So... I've worked out a new bulk-read API to address performance
> bottleneck.  It has some big changes over the current bulk-read API:
>   * You can now also bulk-read positions (but not payloads), but, I
>      have yet to cutover positional queries.
>   * The buffer contains doc deltas, not absolute values, for docIDs
>     and positions (freqs are absolute).
>   * Deleted docs are not filtered out.
>   * The doc & freq buffers need not be "aligned".  For fixed intblock
>     codecs (FOR/PFOR) they will be, but for varint codecs (Simple9/16,
>     Group varint, etc.) they won't be.
> It's still a work in progress...

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