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Re: use of boolean literals

From: Rick Henderson <rickh@netscape.com>
Date: Thu, 23 Apr 1998 16:49:37 -0700
Message-ID: <353FD391.F152C169@netscape.com>
To: Judith Slein <slein@wrc.xerox.com>
CC: www-webdav-dasl@w3.org
Yes we're talking about the same distinction.  Full text search engines don't
in general support that sort of query directly.  There are tricks though that
make it reasonable to support if it were essential.  It doesn't happen
the way it would when implementing using an RDBMS.

I'm inclined to say anyway that the distinction is not essential.  DASL need
not call out the distinction in the query language.  It's another feature to
implement and why is it important?


Judith Slein wrote:

> Just let me make sure we are making the same distinction.  DAV defines
> properties to be name/value pairs.  When I say a property does not exist on
> a given resource, I mean neither that property name nor a value is present.
>  For the property to exist, the name has to be present, but its value could
> be empty or set to NULL.
> I wanted to claim that in the DAV world, it's possible for different
> resources on the same server to have completely different sets of
> properties, so that it would make sense for someone to ask whether the
> "author" property exists on a given resource -- meaning, whether a property
> with that name exists for the resource, regardless of whether its value is
> empty or NULL or "Henderson".
> Is this something a text search engine would have a problem with?
> At 05:16 PM 4/22/98 PDT, Rick Henderson wrote:
> >If the storage meachanism behind the DAV server is a text search engine
> >rather than a RDBMS it may not be so easy to determine the difference
> >between a property with a null value and a property that has never been
> >set.  It's problematic from an implementation standpoint.
> >
> >--Rick
> >*************************************************
> >Rick Henderson            (Netscape)(650)937-3152
> >rickh@netscape.com
> >*************************************************
> >
> >
> >
> >
> >
> Name:                   Judith A. Slein
> E-Mail:         slein@wrc.xerox.com
> Internal Phone:         8*222-5169
> Fax:                    (716) 422-2938
> MailStop:               105-50C
> Web Site:    http://www.nde.wrc.xerox.com/users/Slein/slein.htm

Rick Henderson            (Netscape)(650)937-3152
Received on Thursday, 23 April 1998 19:56:52 UTC

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