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https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13286815#comment-13286815
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Mark Harwood commented on LUCENE-4069:
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bq. Its not worth the complexity
There's no real added complexity in BloomFilterPostingsFormat - it has to be
capable of storing blooms for >1 field anyway and using the fieldname set is
roughly 2 extra lines of code to see if a TermsConsumer needs wrapping or not.
>From a client side you don't have to use this feature - the fieldname set can
>be null in which case it will wrap all fields sent its way. If you do chose to
>supply a set the wrapped PostingsFormat will have the advantage of being
>shared for bloomed and non-bloomed fields. We could add a constructor that
>removes the set and mark the others "expert".
For me this falls into one of the many faster-if-you-know-about-it
optimisations like FieldSelectors or recycling certain objects. Basically a
useful hint to Lucene to save some extra effort but one which you dont *need*
to use.
Lucene-4093 may in future resolve the multi-file issue but I'm not sure it will
do so without significant complication.
> 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
> Reporter: Mark Harwood
> Priority: Minor
> Fix For: 4.0, 3.6.1
>
> Attachments: BloomFilterPostings40.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 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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