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https://issues.apache.org/jira/browse/LUCENE-2680?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12928933#action_12928933
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Jason Rutherglen commented on LUCENE-2680:
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Sorry, spoke too soon, I made a small change to not redundantly delete, in
apply deletes all and TestStressIndexing2 is breaking. I think we need to
"push" segment infos changes to DW as they happen. I'm guessing that segment
infos are being shuffled around and so the infos passed into DW in IW deleteDoc
methods may be out of date by the time deletes are attached to segments.
Hopefully there aren't any lurking deadlock issues with this.
> Improve how IndexWriter flushes deletes against existing segments
> -----------------------------------------------------------------
>
> Key: LUCENE-2680
> URL: https://issues.apache.org/jira/browse/LUCENE-2680
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: Michael McCandless
> Fix For: 4.0
>
> Attachments: LUCENE-2680.patch, LUCENE-2680.patch, LUCENE-2680.patch,
> LUCENE-2680.patch
>
>
> IndexWriter buffers up all deletes (by Term and Query) and only
> applies them if 1) commit or NRT getReader() is called, or 2) a merge
> is about to kickoff.
> We do this because, for a large index, it's very costly to open a
> SegmentReader for every segment in the index. So we defer as long as
> we can. We do it just before merge so that the merge can eliminate
> the deleted docs.
> But, most merges are small, yet in a big index we apply deletes to all
> of the segments, which is really very wasteful.
> Instead, we should only apply the buffered deletes to the segments
> that are about to be merged, and keep the buffer around for the
> remaining segments.
> I think it's not so hard to do; we'd have to have generations of
> pending deletions, because the newly merged segment doesn't need the
> same buffered deletions applied again. So every time a merge kicks
> off, we pinch off the current set of buffered deletions, open a new
> set (the next generation), and record which segment was created as of
> which generation.
> This should be a very sizable gain for large indices that mix
> deletes, though, less so in flex since opening the terms index is much
> faster.
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