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https://issues.apache.org/jira/browse/LUCENE-1476?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12668523#action_12668523
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Michael McCandless commented on LUCENE-1476:
--------------------------------------------
Hmm... when I run the TestDeletesDocIdSet, I don't see as much
improvement: trunk gets 10.507 seconds, patch gets 10.158 (~3.3%
faster). I'm running on OS X 10.5.6, quad core Intel; java version is
"1.6.0_07-b06-153" and I run "java -server -Xbatch -Xmx1024M
-Xms1024M".
But that test is rather synthetic: you create 15,000 docs, then delete
1 in 8, then do a search (for "text") that matches all of the docs.
So I went back to contrib/benchmark... I created a single-segment
index, with 0%, 1%, 2%, 5%, 10%, 20% and 50% deletions, using first 2M
docs from Wikipedia, then ran 5 different queries and compared qps w/
patch vs trunk. Results:
||%tg deletes||query||hits||qps||qpsnew||%tg change||
|0%|147| 4984|5560.1|5486.2| -1.3%|
|0%|text| 97191| 347.3| 339.4| -2.3%|
|0%|1 AND 2| 234634| 22.9| 22.8| -0.4%|
|0%|1| 386435| 88.4| 87.2| -1.4%|
|0%|1 OR 2| 535584| 20.9| 20.9| 0.0%|
|1%|147| 4933|5082.0|1419.2|-72.1%|
|1%|text| 96143| 313.9| 142.0|-54.8%|
|1%|1 AND 2| 232250| 22.1| 18.6|-15.8%|
|1%|1| 382498| 81.0| 62.2|-23.2%|
|1%|1 OR 2| 530212| 20.2| 17.5|-13.4%|
|2%|147| 4883|5133.6|1959.0|-61.8%|
|2%|text| 95190| 315.8| 149.2|-52.8%|
|2%|1 AND 2| 229870| 22.2| 18.4|-17.1%|
|2%|1| 378641| 81.2| 58.9|-27.5%|
|2%|1 OR 2| 524873| 20.3| 17.1|-15.8%|
|5%|147| 4729|5073.6|2600.8|-48.7%|
|5%|text| 92293| 315.2| 166.9|-47.0%|
|5%|1 AND 2| 222859| 22.5| 17.8|-20.9%|
|5%|1| 367000| 81.0| 56.2|-30.6%|
|5%|1 OR 2| 508632| 20.4| 16.3|-20.1%|
|10%|147| 4475|5049.6|2953.7|-41.5%|
|10%|text| 87504| 314.8| 180.9|-42.5%|
|10%|1 AND 2| 210982| 22.9| 17.8|-22.3%|
|10%|1| 347664| 81.5| 53.8|-34.0%|
|10%|1 OR 2| 481792| 21.2| 16.5|-22.2%|
|20%|147| 4012|5045.0|3455.5|-31.5%|
|20%|text| 77980| 317.2| 204.7|-35.5%|
|20%|1 AND 2| 187605| 23.9| 19.2|-19.7%|
|20%|1| 309040| 82.0| 54.7|-33.3%|
|20%|1 OR 2| 428232| 22.3| 17.5|-21.5%|
|50%|147| 2463|5283.2|4731.4|-10.4%|
|50%|text| 48331| 336.9| 290.2|-13.9%|
|50%|1 AND 2| 116887| 28.4| 25.9| -8.8%|
|50%|1| 193154| 86.4| 74.9|-13.3%|
|50%|1 OR 2| 267525| 27.6| 24.9| -9.8%|
I think one major source of slowness is the BitVector.nextSetBit()
impl: it now checks one bit at a time, but it'd be much better to use
OpenBitSet's approach.
I also think, realistically, this approach won't perform very well
until we switch to a sparse representation for the bit set, so that
next() and skipTo() perform well.
> BitVector implement DocIdSet, IndexReader returns DocIdSet deleted docs
> -----------------------------------------------------------------------
>
> Key: LUCENE-1476
> URL: https://issues.apache.org/jira/browse/LUCENE-1476
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Affects Versions: 2.4
> Reporter: Jason Rutherglen
> Priority: Trivial
> Attachments: LUCENE-1476.patch, LUCENE-1476.patch, LUCENE-1476.patch,
> LUCENE-1476.patch, LUCENE-1476.patch, quasi_iterator_deletions.diff,
> quasi_iterator_deletions_r2.diff, searchdeletes.alg, TestDeletesDocIdSet.java
>
> Original Estimate: 12h
> Remaining Estimate: 12h
>
> Update BitVector to implement DocIdSet. Expose deleted docs DocIdSet from
> IndexReader.
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