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https://issues.apache.org/jira/browse/LUCENE-2680?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12928923#action_12928923
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Jason Rutherglen commented on LUCENE-2680:
------------------------------------------
All tests pass except org.apache.lucene.index.TestIndexWriterMergePolicy
testMaxBufferedDocsChange. Odd. I'm looking into this.
{code}
[junit] junit.framework.AssertionFailedError: maxMergeDocs=2147483647;
numSegments=11; upperBound=10; mergeFactor=10;
segs=_65:c5950 _5t:c10->_32 _5u:c10->_32 _5v:c10->_32 _5w:c10->_32 _5x:c10->_32
_5y:c10->_32 _5z:c10->_32 _60:c10->_32 _61:c10->_32 _62:c3->_32 _64:c7->_62
{code}
Also, in IW deleteDocument(*) we're calling a new method, getSegmentInfos which
is sync'ed on IW. Maybe we should use an atomic reference to a read only
segment infos instead?
> 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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