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Posted to dev@lucene.apache.org by "Michael McCandless (JIRA)" <ji...@apache.org> on 2012/05/25 18:21:23 UTC
[jira] [Commented] (LUCENE-4069) Segment-level Bloom filters for a
2 x speed up on rare term searches
[ https://issues.apache.org/jira/browse/LUCENE-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13283574#comment-13283574 ]
Michael McCandless commented on LUCENE-4069:
--------------------------------------------
bq. I see a 35% improvement over standard Codecs on random lookups on a warmed index.
Impressive! This is for primary key lookups?
It looks like the primary keys are GUID-like right? (Ie randomly generated). I wonder if they had some structure instead (eg '%09d' % (id++)) how the results would look...
bq. I also notice that the PulsingCodec is no longer faster than standard Codec - is this news to people as I thought it was supposed to be the way forward?
That's baffling to me: it should only save seeks vs Lucene40 codec, so on a cold index you should see substantial gains, and on a warm index I'd still expect some gains. Not sure what's up...
bq. I can open a seperate JIRA issue for this 4.0 version of the code if that makes more sense.
I think it's fine to do it here? Really 3.6.x is only for bug fixes now ... so I think we should commit this to trunk.
I wonder if you can wrap any other PostingsFormat (ie instead of hard-coding to Lucene40PostingsFormat)? This way users can wrap any PF they have w/ the bloom filter...
Can you use FixedBitSet instead of OpenBitSet? Or is there a reason to use OpenBitSet here...?
> 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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