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From "Marcel Reutegger (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JCR-488) DASL <basicsearch> support
Date Tue, 22 Aug 2006 07:09:18 GMT
    [ http://issues.apache.org/jira/browse/JCR-488?page=comments#action_12429628 ] 
            
Marcel Reutegger commented on JCR-488:
--------------------------------------

Hi Julian,

According to the three-valued-logic rules on:
http://greenbytes.de/tech/webdav/draft-reschke-webdav-search-latest.html#three-valued-logic
imo, it will evaluate to true.

For your example:
[@a=1 or @b=1]

I think the following rule applies:

UNKNOWN or TRUE = TRUE


The reason why I came to the conclusion that only
the negation will pose a problem is the following:
DASL only returns a node when the where clause
evaluates to TRUE. That is, you can convert any
DASL where clause into an two-valued expression
that only returns TRUE or FALSE:

WHERE <dasl-expression>

->

WHERE <dasl-expression> and TRUE


In JCR any expression returns false that would
otherwise return unknown in DASL.

Applying this to the three-valued-logic rules, that
is replacing the unknown values with false gives
the following list of rules:

not FALSE = FALSE
FALSE and TRUE = FALSE
FALSE and FALSE = FALSE
FALSE and FALSE = FALSE
FALSE or TRUE = TRUE
FALSE or FALSE = FALSE
FALSE or FALSE = FALSE

In the boolean world everything but the negation
works out fine.

> DASL <basicsearch> support
> --------------------------
>
>                 Key: JCR-488
>                 URL: http://issues.apache.org/jira/browse/JCR-488
>             Project: Jackrabbit
>          Issue Type: Improvement
>          Components: webdav
>            Reporter: Darren Hartford
>
> http://www.webdav.org/dasl/protocol/draft-davis-dasl-protocol-00.html
> <queryschema> would also be great for application development to dynamically identify
indexed properties.

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