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https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13433045#comment-13433045
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Mark Harwood commented on LUCENE-4069:
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bq. Removing misleading 2X perf gain: it seems to depend heavily on the exact
use case.
Fair enough - the original patch targeted Lucene 3.6 which benefited more
heavily from this technique. The issue then morphed into a 4.x patch where
performance gains were harder to find.
I think the sweet spot is in primary key searches on indexes with ongoing heavy
changes (more segment fragmentation, less OS-level caching?). This is the use
case I am targeting currently and my final tests using our primary-key-counting
test rig saw a 10 to 15% improvement over Pulsing.
bq. I'm asking because I need his feature but I'm stuck with 3.x for a while.
I have a client in a similar situation who are contemplating using the 3.6
patch.
bq. Is there bugs which should be fixed in initial 3.6 patch?
It has been a while since I looked at it - a quick run of "ant test" on my copy
here showed no errors. I will be giving it a closer review if my client decides
to go down this route and can post any fixes here.
I expect if you use the patch and get into trouble you can use an un-patched
version of 3.6 to read the same index files (it should just ignore the extra
"blm" files created by the patched version).
> Segment-level Bloom filters
> ---------------------------
>
> Key: LUCENE-4069
> URL: https://issues.apache.org/jira/browse/LUCENE-4069
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/index
> Affects Versions: 3.6, 4.0-ALPHA
> Reporter: Mark Harwood
> Assignee: Mark Harwood
> Priority: Minor
> Fix For: 4.0-BETA, 5.0
>
> Attachments: 4069Failure.zip, BloomFilterPostingsBranch4x.patch,
> LUCENE-4069-tryDeleteDocument.patch, LUCENE-4203.patch,
> MHBloomFilterOn3.6Branch.patch, PKLookupUpdatePerfTest.java,
> PKLookupUpdatePerfTest.java, PKLookupUpdatePerfTest.java,
> PKLookupUpdatePerfTest.java, PrimaryKeyPerfTest40.java
>
>
> An addition to each segment which stores a Bloom filter for selected fields
> in order to give fast-fail to term searches, helping avoid wasted disk access.
> Best suited for low-frequency fields e.g. primary keys on big indexes with
> many segments but also speeds up general searching in my tests.
> Overview slideshow here:
> http://www.slideshare.net/MarkHarwood/lucene-bloomfilteredsegments
> Benchmarks based on Wikipedia content here: http://goo.gl/X7QqU
> Patch based on 3.6 codebase attached.
> There are no 3.6 API changes currently - to play just add a field with "_blm"
> on the end of the name to invoke special indexing/querying capability.
> Clearly a new Field or schema declaration(!) would need adding to APIs to
> configure the service properly.
> Also, a patch for Lucene4.0 codebase introducing a new PostingsFormat
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