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From "Robert Muir (JIRA)" <>
Subject [jira] Commented: (LUCENE-2458) queryparser makes all CJK queries phrase queries regardless of analyzer
Date Wed, 26 May 2010 12:14:32 GMT


Robert Muir commented on LUCENE-2458:

bq. I've got to -1 this commit.

As mentioned on apache's website:
To prevent vetos from being used capriciously, they must be accompanied by a technical justification
showing why the change is bad (opens a security exposure, negatively affects performance,
etc.). A veto without a justification is invalid and has no weight.

No one has been able to provide any technical justifications, only subjective opinions.

When standard test collections were used, it was shown that this behavior significant hurts
CJK and delivers only 10% of standard IR techniques (not generating phrases but using boolean
word/bigram queries). See Ivan's results above. This isn't surprising since CJK IR has been
pretty well studied, there is nothing new here.

At the same time, when english test collections were used, there was no difference, on the
contrary, it only tended to slightly improve relevance for english, too.

Why do we even bother trying to start an openrelevance project if people do not want to go
with the scientific method but prefer subjective opinion?

> queryparser makes all CJK queries phrase queries regardless of analyzer
> -----------------------------------------------------------------------
>                 Key: LUCENE-2458
>                 URL:
>             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
> 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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