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From "Michael McCandless (JIRA)" <>
Subject [jira] [Commented] (LUCENE-4069) Segment-level Bloom filters for a 2 x speed up on rare term searches
Date Mon, 09 Jul 2012 19:15:36 GMT


Michael McCandless commented on LUCENE-4069:

I ran with with the fastest configuration (lookupByReader=false,
shareEnums=true, doSortKeys=true, useDocValues=true,
doDirectDelete=true, useBase36=true).

I used MMapDir, 10M numDocs and keySpaceSize, Java 1.7.0_04, 2 GB
starting/max heap.

With doWorstCaseFlushing=false:

    55978 ms

    49880 ms

    55965 ms

    56059 ms

With doWorstCaseFlushing=true:

    61097 ms

    53698 ms

    61066 ms

    61355 ms

So Bloom is ~11-12% faster.  Very curious that Lucene40, Pulsing and
Memory are basically the same!

> Segment-level Bloom filters for a 2 x speed up on rare term searches
> --------------------------------------------------------------------
>                 Key: LUCENE-4069
>                 URL:
>             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: BloomFilterPostingsBranch4x.patch, LUCENE-4069-tryDeleteDocument.patch,
> 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:
> Benchmarks based on Wikipedia content here:
> 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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