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https://issues.apache.org/jira/browse/LUCENE-843?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12506811
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Michael McCandless commented on LUCENE-843:
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> Does DocumentsWriter also solve the problem DocumentWriter had
> before LUCENE-880? I believe the answer is yes. Even though you
> close the TokenStreams in the finally clause of invertField() like
> DocumentWriter did before 880 this is safe, because addPosition()
> serializes the term strings and payload bytes into the posting hash
> table right away. Is that right?
That's right. When I merged in the fix for LUCENE-880, I realized
with this patch it's fine to close the token stream immediately after
processing all of its tokens because everything about the token stream
has been "absorbed" into postings hash.
> the benchmarks you run focus on measuring the pure indexing
> performance. I think it would be interesting to know how big the
> speedup is in real-life scenarios, i. e. with StandardAnalyzer and
> maybe even HTML parsing? For sure the speedup will be less, but it
> should still be a significant improvement. Did you run those kinds
> of benchmarks already?
Good question ... I haven't measured the performance cost of using
StandardAnalyzer or HTML parsing but I will test & post back.
> improve how IndexWriter uses RAM to buffer added documents
> ----------------------------------------------------------
>
> Key: LUCENE-843
> URL: https://issues.apache.org/jira/browse/LUCENE-843
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Affects Versions: 2.2
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Attachments: index.presharedstores.cfs.zip,
> index.presharedstores.nocfs.zip, LUCENE-843.patch, LUCENE-843.take2.patch,
> LUCENE-843.take3.patch, LUCENE-843.take4.patch, LUCENE-843.take5.patch,
> LUCENE-843.take6.patch, LUCENE-843.take7.patch, LUCENE-843.take8.patch,
> LUCENE-843.take9.patch
>
>
> I'm working on a new class (MultiDocumentWriter) that writes more than
> one document directly into a single Lucene segment, more efficiently
> than the current approach.
> This only affects the creation of an initial segment from added
> documents. I haven't changed anything after that, eg how segments are
> merged.
> The basic ideas are:
> * Write stored fields and term vectors directly to disk (don't
> use up RAM for these).
> * Gather posting lists & term infos in RAM, but periodically do
> in-RAM merges. Once RAM is full, flush buffers to disk (and
> merge them later when it's time to make a real segment).
> * Recycle objects/buffers to reduce time/stress in GC.
> * Other various optimizations.
> Some of these changes are similar to how KinoSearch builds a segment.
> But, I haven't made any changes to Lucene's file format nor added
> requirements for a global fields schema.
> So far the only externally visible change is a new method
> "setRAMBufferSize" in IndexWriter (and setMaxBufferedDocs is
> deprecated) so that it flushes according to RAM usage and not a fixed
> number documents added.
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