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https://issues.apache.org/jira/browse/LUCENE-2723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12986568#action_12986568
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Robert Muir commented on LUCENE-2723:
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Simon, just took a quick glance (not a serious review, all the bulkpostings
stuff is heavy).
I agree with the idea that Codecs should only need to implement the bulk api at
a minimum:
if all serious stuff (queries) is using these bulk apis, then the "friendly"
iterator methods
can simply be a wrapper over it.
but separately, i know there are some performance degradations with the bulk
APIs today
versus trunk... (with the same index). I know if i use other fixed-int codecs i
see these same
problems, so I dont think its just Standard's implementation: pretty sure the
issue is somewhere
with advance()/jump().
I really wish we could debug whatever this performance problem is, just in case
the bulk APIs
themselves need changing... a little concerned about them at the moment thats
all...
not sure it should stand in the way of your patch, just saying I don't like the
performance
regression.
> 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-BulkEnumWrapper.patch,
> LUCENE-2723-termscorer.patch, LUCENE-2723-termscorer.patch,
> LUCENE-2723-termscorer.patch, LUCENE-2723.patch, LUCENE-2723.patch,
> LUCENE-2723.patch, LUCENE-2723.patch, LUCENE-2723.patch, LUCENE-2723.patch,
> LUCENE-2723_bulkvint.patch, LUCENE-2723_facetPerSeg.patch,
> LUCENE-2723_facetPerSeg.patch, LUCENE-2723_openEnum.patch,
> LUCENE-2723_termscorer.patch, LUCENE-2723_wastedint.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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