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From "Joshua O'Madadhain" <jmad...@ics.uci.edu>
Subject Re: Empty phrase search
Date Tue, 17 Dec 2002 07:03:42 GMT
Minh:

Why not just use a special character or string (one that won't appear in a
non-empty field) to represent an empty field?  It doesn't have to appear
in the user interface, if that's a concern; you could convert a query
including "FieldA:NULL" (or whatever) into a query containing
"FieldA:emptyfield" automatically.

This allows you to finesse the entire issue of adding something to
Lucene--which may be for the best anyway, since this is really just a
special case of looking for fields whose contents have a specific
characteristic.

Good luck--

Joshua O'Madadhain

 jmadden@ics.uci.edu...Obscurium Per Obscurius...www.ics.uci.edu/~jmadden
  Joshua O'Madadhain: Information Scientist, Musician, Philosopher-At-Tall
 It's that moment of dawning comprehension that I live for--Bill Watterson
My opinions are too rational and insightful to be those of any organization.

On Tue, 17 Dec 2002, Minh Kama Yie wrote:

> Thanks for that Peter.
> 
> Unfortunately I'm not looking for "all" documents but rather documents where
> the fields can be empty.
> Hence using the universal field wouldn't quite work.
> The "empty:true" approach is interesting however it effectively doubles the
> number of indexable fields for a document.
> 
> Need to assess whether or not we want to support this feature I guess.
> 
> Currently, considering Lucene's architecture this feature needs to be
> inherently supported rather than worked around with various fields I think
> for it to be used/done properly...
> 
> Would anyone be able to point me in the general direction of where to look
> in the Lucene code to attempt this?
> Hopefully this way I can give a proper cost/benefit analysis as to whether
> or not to support this feature...and if all goes well, release something
> back for the great work you guys do....
> 
> 
> ----- Original Message -----
> From: "Peter Carlson" <carlson@bookandhammer.com>
> To: "Lucene Users List" <lucene-user@jakarta.apache.org>
> Sent: Tuesday, December 17, 2002 4:25 PM
> Subject: Re: Empty phrase search
> 
> 
> > I don't think so.
> >
> > One approach to look for everything, or not something is to add a field
> > to each document which is a constant value. Like a field named exists
> > and a value of true.
> >
> > Then you can do search like
> >
> > exists:true NOT microsoft
> >
> > This will find all documents without the term microsoft in them.
> >
> > Just to have it find documents with nothing might be a little tricky.
> > You might want to put a field in the document which indicates the size
> > or something like that. Or just create an empty field and look for
> >
> > empty:true
> >
> > I hope this rambling helps
> >
> > --Peter
> >
> > On Monday, December 16, 2002, at 03:24 PM, Minh Kama Yie wrote:
> >
> > > Hi guys,
> > >
> > > Just wondering if lucene indexes empty strings and if so, how to
> > > search for this using the query language?
> > >
> > >
> > > Regards,
> > >
> > > Minh Kama Yie
> > >
> > > This message is intended only for the named recipient.
> > > If you are not the intended recipient you are notified that
> > > disclosing, copying, distributing or taking any action
> > > in reliance on the contents of this information is strictly
> > > prohibited.
> >
> >
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