[jira] [Commented] (LUCENE-5879) Add auto-prefix terms to block tree terms dict

["Michael McCandless (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-5879?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14131593#comment-14131593 ] 

Michael McCandless commented on LUCENE-5879:
--------------------------------------------

Hmm, one problem here is ... with this patch we are inserting
auto-prefix terms for numeric fields which is sort of silly (prefix
terms of prefix terms).  Not sure if/how to prevent that... I guess we
could do something hacky and try to detect when writing the postings
that it's a numeric field ... hmm.

I removed the DEBUG nocommits and ran a trunk vs patch perf test on
all English wikipedia "medium" docs (33.3M) and it didn't look like
there was any real change, just noise.


> 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: 4.10, 5.0
>
>         Attachments: 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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