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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-2458) queryparser makes all CJK queries phrase queries regardless of analyzer
Date Wed, 26 May 2010 19:41:37 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12871907#action_12871907
] 

Michael McCandless commented on LUCENE-2458:
--------------------------------------------

I think the latest patch is an OK step forward.  Yeah it's not
perfect, but it's better than what we have today.  Progress not
perfection.

QP (and more generally all of Lucene's core) should aim to be language
neutral, and it's not now.  This patch improves that (defaulting the
auto-PhraseQuery to off, by version).

Yes, compound/syn handling in English should be available, but the way
QP does this is really quite broken (the analyzer can't do multi-words
syns).

There are deep questions/ideas about how to properly do multi-words
syns/compounds (see LUCENE-1622 -- we really need to change the index,
to store "span" of a token).  I'm no longer sure that having analyzer
mark tokens that should be made into PhraseQuery is the right
approach... eg with the contrib QP, a plugin could directly tweak the
query tree, instead of being forced to use a token stream to
communicate this.


> queryparser makes all CJK queries phrase queries regardless of analyzer
> -----------------------------------------------------------------------
>
>                 Key: LUCENE-2458
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2458
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: QueryParser
>            Reporter: Robert Muir
>            Assignee: Robert Muir
>            Priority: Blocker
>             Fix For: 3.1, 4.0
>
>         Attachments: LUCENE-2458.patch, LUCENE-2458.patch, LUCENE-2458.patch
>
>
> The queryparser automatically makes *ALL* CJK, Thai, Lao, Myanmar, Tibetan, ... queries
into phrase queries, even though you didn't ask for one, and there isn't a way to turn this
off.
> This completely breaks lucene for these languages, as it treats all queries like 'grep'.
> Example: if you query for f:abcd with standardanalyzer, where a,b,c,d are chinese characters,
you get a phrasequery of "a b c d". if you use cjk analyzer, its no better, its a phrasequery
of  "ab bc cd", and if you use smartchinese analyzer, you get a phrasequery like "ab cd".
But the user didn't ask for one, and they cannot turn it off.
> The reason is that the code to form phrase queries is not internationally appropriate
and assumes whitespace tokenization. If more than one token comes out of whitespace delimited
text, its automatically a phrase query no matter what.
> The proposed patch fixes the core queryparser (with all backwards compat kept) to only
form phrase queries when the double quote operator is used. 
> Implementing subclasses can always extend the QP and auto-generate whatever kind of queries
they want that might completely break search for languages they don't care about, but core
general-purpose QPs should be language independent.

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