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From "Uwe Schindler (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4069) Segment-level Bloom filters for a 2 x speed up on rare term searches
Date Tue, 17 Jul 2012 09:26:34 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13416039#comment-13416039
] 

Uwe Schindler commented on LUCENE-4069:
---------------------------------------

bq. Actually, re-thinking this, I suspect rather than creating our own, I can use Java's existing
SPI framework for hashing in the form of MessageDigest. I'll take a closer look into that...

That's a good idea. MessageDigest.getInstance(name) should be the way to go. And this name
string is encoded to the index. If the MessageDigest API is enough then one can e.g. use bouncycastle
by just plugging into the calsspath. If on opening index, this is not available, he will get
Exception just like when codec/postingsformat is missing.
                
> Segment-level Bloom filters for a 2 x speed up on rare term searches
> --------------------------------------------------------------------
>
>                 Key: LUCENE-4069
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4069
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: core/index
>    Affects Versions: 3.6, 4.0-ALPHA
>            Reporter: Mark Harwood
>            Priority: Minor
>             Fix For: 4.0
>
>         Attachments: 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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