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From "Mark Harwood (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4069) Segment-level Bloom filters for a 2 x speed up on rare term searches
Date Mon, 28 May 2012 20:07:23 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13284536#comment-13284536
] 

Mark Harwood commented on LUCENE-4069:
--------------------------------------

bq.  I wonder if that also helps indexing in terms of applying deletes. did you test that

I've not looked into that particularly but I imagine this may be relevant. 

Thanks for the tips for making the patch more generic. I'll get on it tomorrow and changed
to FixedBitSet while I'm at it.

bq. I also wonder if we can extract a "bloomfilter" class into utils

There's some reusable stuff in this patch for downsizing the Bitset (according to desired
saturation levels) having accumulated a stream of values.
                
> 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
>            Reporter: Mark Harwood
>            Priority: Minor
>             Fix For: 3.6.1
>
>         Attachments: BloomFilterCodec40.patch, MHBloomFilterOn3.6Branch.patch, PrimaryKey40PerformanceTestSrc.zip
>
>
> 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 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.

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