[jira] Commented: (LUCENE-2836) FieldCache rewrite method for MultiTermQueries

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

    [ https://issues.apache.org/jira/browse/LUCENE-2836?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12976707#action_12976707 ] 

Michael McCandless commented on LUCENE-2836:
--------------------------------------------

This is a great speedup for the hard wildcard queries!

I think we should commit it, but jdoc the limitations (eg single valued).

I'll add a "whole title" field to luceneutil so we can more naturally test wildcards...

> FieldCache rewrite method for MultiTermQueries
> ----------------------------------------------
>
>                 Key: LUCENE-2836
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2836
>             Project: Lucene - Java
>          Issue Type: New Feature
>            Reporter: Robert Muir
>             Fix For: 4.0
>
>         Attachments: LUCENE-2836.patch
>
>
> For some MultiTermQueries, like RangeQuery we have a FieldCacheRangeFilter etc (in this case its particularly optimized).
> But in the general case, since LUCENE-2784 we can now have a rewrite method to rewrite any MultiTermQuery 
> using the FieldCache, because MultiTermQuery's getEnum no longer takes IndexReader but Terms, and all the 
> FilteredTermsEnums are now just real TermsEnum decorators.
> In cases like low frequency queries this is actually slower (I think this has been shown for numeric ranges before too),
> but for the really high-frequency cases like especially ugly wildcards, regexes, fuzzies, etc, this can be several times faster 
> using the FieldCache instead, since all the terms are in RAM and automaton can blast through them quicker.

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