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https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13416084#comment-13416084
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Mark Harwood commented on LUCENE-4069:
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bq. MessageDigest.getInstance(name) should be the way to go
I'm less keen now - a quick scan of the docs around MessageDigest throws up
some issues:
1) SPI registration of MessageDigest providers looks to get into permissions
hell as it is closely related to security - see
http://docs.oracle.com/javase/1.4.2/docs/guide/security/CryptoSpec.html#ProviderInstalling
which talks about the steps required to approve a trusted "provider".
2) MessageDigest as an interface is designed to stream content in potentially
many method calls past the hashing algo. MurmurHash2.java is not currently
written to process content this way and suits our needs in hashing small blocks
of content in one hit.
For these 2 reasons it looks like MessageDigest may be a pain to adopt and the
existing approach proposed in this patch may be preferable.
> 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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