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https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13415604#comment-13415604
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Michael McCandless commented on LUCENE-4069:
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{quote}
bq. It's the unique term count (for this one segment) that you need right?
Yes, I need it before I start processing the stream of terms being flushed.
{quote}
At a minimum I think before committing we should make the
SegmentWriteState accessible. EG then at least I can use numDocs for
my primary key field.
I really don't like how easy it is to silently mis-configure this PF:
the default 8 MB is way to high for an NRT setting and way too low for
a large index.
bq. Currently all PostingFormat impls that extend BloomFilterPostingsFormat can
be anonymous (i.e. unregistered via SPI).
Hmm why is anonymity at search time important? I think that's a
non-feature, and we shouldn't make our core code more complex for it?
Ie, it's fine to require the app to have to make a named PF (that is
accessible via SPI), implementing all their custom bloom logic (which
fields are bloom'd, what hash to use, etc.).
When an app makes a custom Codec/PostingsFormat, it's expected that
that class is accessible via SPI at both index time and search time.
> 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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