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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (LUCENE-5879) Add auto-prefix terms to block tree terms dict
Date Wed, 01 Apr 2015 21:46:54 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-5879?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Michael McCandless updated LUCENE-5879:
---------------------------------------
    Attachment: LUCENE-5879.patch

Another iteration, adding a test case as Rob suggested.  It was somewhat tricky because BasePFTestCase
tests all IndexOptions but this new PF only supports DOCS.

So, I factored out a RandomPostingsTester (in test-framework) from BasePFTestCase, which lets
you specify which IndexOptions to test, and then added TestAutoPrefixPF to use that.

This process managed to find a couple latent bugs in BasePostingsFormatTestCase's SeedPostings!

Tests seem to pass ... I ran distributed beasting for 17 iters.

I think it's ready.

> Add auto-prefix terms to block tree terms dict
> ----------------------------------------------
>
>                 Key: LUCENE-5879
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5879
>             Project: Lucene - Core
>          Issue Type: New Feature
>          Components: core/codecs
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>             Fix For: 5.0, Trunk
>
>         Attachments: LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch,
LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch,
LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch, LUCENE-5879.patch
>
>
> This cool idea to generalize numeric/trie fields came from Adrien:
> Today, when we index a numeric field (LongField, etc.) we pre-compute
> (via NumericTokenStream) outside of indexer/codec which prefix terms
> should be indexed.
> But this can be inefficient: you set a static precisionStep, and
> always add those prefix terms regardless of how the terms in the field
> are actually distributed.  Yet typically in real world applications
> the terms have a non-random distribution.
> So, it should be better if instead the terms dict decides where it
> makes sense to insert prefix terms, based on how dense the terms are
> in each region of term space.
> This way we can speed up query time for both term (e.g. infix
> suggester) and numeric ranges, and it should let us use less index
> space and get faster range queries.
>  
> This would also mean that min/maxTerm for a numeric field would now be
> correct, vs today where the externally computed prefix terms are
> placed after the full precision terms, causing hairy code like
> NumericUtils.getMaxInt/Long.  So optos like LUCENE-5860 become
> feasible.
> The terms dict can also do tricks not possible if you must live on top
> of its APIs, e.g. to handle the adversary/over-constrained case when a
> given prefix has too many terms following it but finer prefixes
> have too few (what block tree calls "floor term blocks").



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