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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 Tue, 17 Jul 2012 09:21:36 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13416037#comment-13416037
] 

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

bq.  If a special decoder for foobar is needed, it must be loadable by SPI. 

I think we are in agreement on the broad principles. The fundamental question here though
is do you want to treat an index's choice of Hash algo as something that would require a new
SPI-registered PostingsFormat to decode or can that be handled as I have done here with a
general purpose SPI framework for hashing algos? 

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...


                
> 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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